Cancer
Classification & external resources

When normal cells are damaged beyond repair, they are eliminated by apoptosis. Cancer cells avoid apoptosis and continue to multiply in an unregulated manner
DiseasesDB	28843
MedlinePlus	001289
MeSH	C04

Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). Cancer may affect people at all ages, but risk tends to increase with age. It is one of the principal causes of death in developed countries. This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... A cell undergoing apoptosis. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... MedlinePlus (medlineplus. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... A disease or medical condition is an abnormality that causes discomfort, dysfunction, distress, or death to the person afflicted or those in contact with the person. ... This does not adequately cite its references or sources. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... The human lymphatic system The lymphatic system is a complex network of lymphoid organs, lymph nodes, lymph ducts, lymph tissues, lymph capillaries and lymph vessels that produce and transport lymph fluid from tissues to the circulatory system. ... This list shows causes of human deaths, worldwide, for a single year (2002) arranged by the associated mortality rate. ... World map indicating Human Development Index (as of 2004). ...

There are many types of cancer. Severity of symptoms depends on the site and character of the malignancy and whether there is metastasis. A definitive diagnosis usually requires the histologic examination of tissue by a pathologist. This tissue is obtained by biopsy or surgery. Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. As research develops, treatments are becoming more specific for the type of cancer pathology. Drugs that target specific cancers already exist for several types of cancer. If untreated, cancers may eventually cause illness and death, though this is not always the case. A thin section of lung tissue stained with hematoxylin and eosin. ... Anatomic pathology is a medical specialty (a branch of pathology) that is concerned with the diagnosis of disease based on the gross, microscopic, and molecular examination of cells and tissues. ... Brain biopsy A biopsy (in Greek: bios = life and opsy = look/appearance) is a medical test involving the removal of cells or tissues for examination. ... A cardiothoracic surgeon performs a mitral valve replacement at the Fitzsimons Army Medical Center. ... The stage of a cancer is a descriptor (usually numbers I to IV) of how much the cancer has spread. ... A cardiothoracic surgeon performs a mitral valve replacement at the Fitzsimons Army Medical Center. ... Chemotherapy is the use of chemical substances to treat disease. ... Clinac 2100 C100 accelerator Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). ... This article or section does not adequately cite its references or sources. ...

The unregulated growth that characterizes cancer is caused by damage to DNA, resulting in mutations to genes that encode for proteins controlling cell division. Many mutation events may be required to transform a normal cell into a malignant cell. These mutations can be caused by radiation, chemicals or physical agents that cause cancer, which are called carcinogens, or by certain viruses that can insert their DNA into the human genome. Mutations occur spontaneously, and may be passed down from one cell generation to the next as a result of mutations within germ lines. However, some carcinogens also appear to work through non-mutagenic pathways that affect the level of transcription of certain genes without causing genetic mutation. The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... It has been suggested that mutant be merged into this article or section. ... For other meanings of this term, see gene (disambiguation). ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... Germline is a word used in biology and genetics. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ...

Many forms of cancer are associated with exposure to environmental factors such as tobacco smoke, radiation, alcohol, and certain viruses. Some risk factors can be avoided or reduced. In epidemiology, environmental factors are those determinants of disease that are not transmitted genetically. ... Tobacco smoking is the act of smoking tobacco products, especially cigarettes and cigars. ... Radiation as used in physics, is energy in the form of waves or particles. ... The effects of alcohol on the human body can take several forms. ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus is a microscopic particle (ranging in size from 20 - 300 nm) that can infect the cells of a biological organism. ...

[edit] History

Today, the Greek term carcinoma is the medical term for a malignant tumor derived from epithelial cells. It is Celsus who translated carcinos into the Latin cancer, also meaning crab. Galen used "oncos" to describe all tumours, the root for the modern word oncology.^[1] In medicine, carcinoma apanting dog named rufis It is malignant by definition: carcinomas invade surrounding tissues and organs, and may spread to lymph nodes and distal sites (metastasis). ... Types of epithelium This article discusses the epithelium, an animal anatomical structure. ... Aulus Cornelius Celsus Aulus Cornelius Celsus (25 BC—50) was a Roman encyclopedist and possibly, although not likely, a physician. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Galen (Greek: Γαληνός, Galinos; Latin: Claudius Galenus; AD 129 –c. ... Oncology is the medical subspecialty dealing with the study and treatment of cancer. ...

Breast cancer in a mastectomy specimen (top). The cancerous tumour (pale yellow) resembles the figure of a crab, giving the disease its name.

Hippocrates described several kinds of cancers. He called benign tumours oncos, Greek for swelling, and malignant tumours carcinos, Greek for crab or crayfish. This name probably comes from the appearance of the cut surface of a solid malignant tumour, with a roundish hard center surrounded by pointy projections, vaguely resembling the shape of a crab (see photo). He later added the suffix -oma, Greek for swelling, giving the name carcinoma. Since it was against Greek tradition to open the body, Hippocrates only described and made drawings of outwardly visible tumors on the skin, nose, and breasts. Treatment was based on the humor theory of four bodily fluids (black and yellow bile, blood, and phlegm). According to the patient's humor, treatment consisted of diet, blood-letting, and/or laxatives. Through the centuries it was discovered that cancer could occur anywhere in the body, but humor-theory based treatment remained popular until the 19th century with the discovery of cells. Image File history File linksMetadata Download high-resolution version (414x618, 339 KB) Summary Top photo taken by emmanuelm. ... Image File history File linksMetadata Download high-resolution version (414x618, 339 KB) Summary Top photo taken by emmanuelm. ... Hippocrates of Cos II or Hippokrates of Kos (c. ... Superfamilies Dromiacea Homolodromioidea Dromioidea Homoloidea Eubrachyura Raninoidea Cyclodorippoidea Dorippoidea Calappoidea Leucosioidea Majoidea Hymenosomatoidea Parthenopoidea Retroplumoidea Cancroidea Portunoidea Bythograeoidea Xanthoidea Bellioidea Potamoidea Pseudothelphusoidea Gecarcinucoidea Cryptochiroidea Pinnotheroidea * Ocypodoidea * Grapsoidea * An asterisk (*) marks the crabs included in the clade Thoracotremata. ... Families Astacoidea   Astacidae   Cambaridae Parastacoidea   Parastacidae Crayfish, often referred to as crawfish or crawdad, are freshwater crustaceans resembling small lobsters, to which they are closely related. ... The humor theory or humour theory was a theory of the makeup and workings of the human body adopted by ancient Greek and Roman physicians and philosophers. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ...

Though treatment remained the same, in the 16th and 17th centuries it became more acceptable for doctors to dissect bodies to discover the cause of death. The German professor Wilhelm Fabry believed that breast cancer was caused by a milk clot in a mammary duct. The Dutch professor Francois de la Boe Sylvius, a follower of Descartes, believed that all disease was the outcome of chemical processes, and that acidic lymph fluid was the cause of cancer. His contemporary Nicolaes Tulp believed that cancer was a poison that slowly spreads, and concluded that it was contagious.^[2] Post-mortem, postmortem and post mortem redirect here. ... Wilhelm Fabry (also William Fabry, Guilelmus Fabricius Hildanus, or Fabricius von Hilden) (June 25, 1560 in Hilden-1634). ... Franciscus Sylvius (1614-1672), also known as Franz De Le Boe, was physician and scientist (chemist, physiologist and anatomist). ... René Descartes René Descartes (IPA: , March 31, 1596 – February 11, 1650), also known as Cartesius, worked as a philosopher and mathematician. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

With the widespread use of the microscope in the 18th century, it was discovered that the 'cancer poison' spread from the primary tumor through the lymph nodes to other sites ("metastasis"). The use of surgery to treat cancer had poor results due to problems with hygiene. The renowned Scottish surgeon Alexander Monro saw only 2 breast tumor patients out of 60 surviving surgery for two years. In the 19th century, asepsis improved surgical hygiene and as the survival statistics went up, surgical removal of the tumor became the primary treatment for cancer. With the exception of William Coley who in the late 1800s felt that the rate of cure after surgery had been higher before asepsis (and who injected bacteria into tumors with mixed results), cancer treatment became dependent on the individual art of the surgeon at removing a tumor. During the same period, the idea that the body was made up of various tissues, that in turn were made up of millions of cells, laid rest the humor-theories about chemical imbalances in the body. The age of cellular pathology was born. Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ... A cardiothoracic surgeon performs a mitral valve replacement at the Fitzsimons Army Medical Center. ... Three generations of distinguished Scots physicians — grandfather, father, and son — were all called Alexander Monro. ... Asepsis is the practice to reduce or eliminate contaminants (such as bacteria, viruses, fungi, and parasites) from entering the operative field in surgery or medicine to prevent infection. ... William Coley was a cancer researcher who developed a treatment based on provoking an immune response to bacteria. ... Cellular pathology is the branch of general pathology studying the cellular basis of disease. ...

When Marie Curie and Pierre Curie discovered radiation at the end of the 19th century, they stumbled upon the first effective non-surgical cancer treatment. With radiation came also the first signs of multi-disciplinary approaches to cancer treatment. The surgeon was no longer operating in isolation, but worked together with hospital radiologists to help patients. The complications in communication this brought, along with the necessity of the patient's treatment in a hospital facility rather than at home, also created a parallel process of compiling patient data into hospital files, which in turn led to the first statistical patient studies. Maria Skłodowska-Curie (born Maria Skłodowska; known in France, where she lived most of her life, as Marie Curie, aka Madame Curie; Warsaw, November 7, 1867 – July 4, 1934, Sancellemoz, France) was a Polish-French physicist and chemist. ... // Pierre Curie (Paris, France, May 15, 1859 – April 19, 1906, Paris) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity. ... Radiation as used in physics, is energy in the form of waves or particles. ...

Cancer patient treatment and studies were restricted to individual physicians' practices until World War II, when medical research centers discovered that there were large international differences in disease incidence. This insight drove national public health bodies to make it possible to compile health data across practises and hospitals, a process that many countries do today. The Japanese medical community observed that the bone marrow of bomb victims in Hiroshima and Nagasaki was completely destroyed. They concluded that diseased bone marrow could also be destroyed with radiation, and this led to the discovery of bone marrow transplants for leukemia. Since WWII, trends in cancer treatment are to improve on a micro-level the existing treatment methods, standardize them, and globalize them as a way to find cures through epidemiology and international partnerships. Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... In optics one considers angles of incidence. ... For other uses, see Hiroshima (disambiguation). ... Nagasaki (Japanese: 長崎市, Nagasaki-shi  , long peninsula) is the capital and the largest city of Nagasaki Prefecture in Japan. ... Leukemia or leukaemia (see spelling differences) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). ... When normal cells are damaged beyond repair, they are eliminated by apoptosis. ... Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. ...

[edit] Nomenclature and classification

The following closely related terms may be used to designate abnormal growths:

• Neoplasia and neoplasm are the scientific designations for cancerous diseases. This group contains a large number of different diseases. Neoplasms can be benign or malignant.
• Cancer is a widely used word that is usually understood as synonymous with malignant neoplasm. It is occasionally used instead of carcinoma, a sub-group of malignant neoplasms. Because of its overwhelming popularity relative to 'neoplasia', it is used frequently instead of 'neoplasia', even by scientists and physicians, especially when discussing neoplastic diseases as a group.
• Tumor in medical language simply means swelling or lump, either neoplastic, inflammatory or other. In common language, however, it is synonymous with 'neoplasm', either benign or malignant. This is inaccurate since some neoplasms do not usually form tumors, for example leukemia or carcinoma in situ.
• Paraneoplasia is a disturbance associated with a neoplasm but not related to the invasion of the primary or a secondary (metastatic) tumour. Disturbances can be hormonal, neurological, hematological, biochemical or otherwise clinical.

Cancers are classified by the type of cell that resembles the tumor and, therefore, the tissue presumed to be the origin of the tumor. The following general categories are usually accepted: Neoplasia (new growth in Greek) is abnormal, disorganized growth in a tissue or organ, usually forming a distinct mass. ... Benign can refer to any medical condition which, untreated or with symptomatic therapy, will not become life-threatening. ... In medicine, malignant is a clinical term that is used to describe a clinical course that progresses rapidly to death. ... In medicine, carcinoma apanting dog named rufis It is malignant by definition: carcinomas invade surrounding tissues and organs, and may spread to lymph nodes and distal sites (metastasis). ... Tumor or tumour literally means swelling, and is sometimes still used with that meaning. ... Leukemia or leukaemia (see spelling differences) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). ... Carcinoma in situ is present when a tumor has been detected that has the characteristics of malignancy but has not invaded other tissues. ... A paraneoplastic phenomenon is a disease or symptom that is the consequence of the presence of cancer in the body, but is not due to the local presence of cancer cells. ...

• Carcinoma: malignant tumors derived from epithelial cells. This group represents the most common cancers, including the common forms of breast, prostate, lung and colon cancer.
• Lymphoma and Leukemia: malignant tumors derived from blood and bone marrow cells
• Sarcoma: malignant tumors derived from connective tissue, or mesenchymal cells
• Mesothelioma: tumors derived from the mesothelial cells lining the peritoneum and the pleura.
• Glioma: tumors derived from glia, the most common type of brain cell
• Germinoma: tumors derived from germ cells, normally found in the testicle and ovary
• Choriocarcinoma: malignant tumors derived from the placenta

Malignant tumors are usually named using the Latin or Greek root of the organ as a prefix and the above category name as the suffix. For instance, a malignant tumor of liver cells is called hepatocarcinoma; a malignant tumor of the fat cells is called liposarcoma. For common cancers, the English organ name is used. For instance, the most common type of breast cancer is called ductal carcinoma of the breast or mammary ductal carcinoma. Here, the adjective ductal refers to the appearance of the cancer under the microscope, resembling normal breast ducts. In medicine, carcinoma apanting dog named rufis It is malignant by definition: carcinomas invade surrounding tissues and organs, and may spread to lymph nodes and distal sites (metastasis). ... Types of epithelium This article discusses the epithelium, an animal anatomical structure. ... A pregnant womans breasts. ... The prostate is an exocrine gland of the male mammalian reproductive system. ... Respiratory system The lungs flank the heart and great vessels in the chest cavity. ... For the article about the punctuation symbol, see Colon (punctuation). ... This article is about lymphoma in humans. ... Leukemia or leukaemia (see spelling differences) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Grays Anatomy illustration of cells in bone marrow. ... A sarcoma is a cancer of the connective or supportive tissue (bone, cartilage, fat, muscle, blood vessels) and soft tissue. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... Mesenchyme (also known as embryonic connective tissue) is the mass of tissue that develops mainly from the mesoderm (the middle layer of the trilaminar germ disc) of an embryo. ... The mesothelium is a membrane that forms the lining of several body cavities: the pleura (thoracal cavity), peritoneum (abdominal cavity) and pericardium (heart sac). ... In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdominal cavity - it covers most of the intra-abdominal organs. ... In anatomy, the pleural cavity is the potential space between the lungs and the chest wall. ... A glioma is a type of primary central nervous system (CNS) tumor that arises from glial cells. ... In animals the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... Germinomas are neoplasia (commonly referred to as cancers or tumors) which most closely resemble germ line cells. ... The testicles, or testes (singular testis), are the male generative glands in animals. ... For ovary as part of plants see ovary (plants) Ovaries are egg-producing reproductive organs found in female organisms. ... Choriocarcinoma is a rare cancer of the placenta, curable by chemotherapy. ... The placenta is an ephemeral (temporary) organ present in female placental vertebrates during gestation (pregnancy), but a placenta has evolved independently also in other animals as well, for instance scorpions and velvet worms. ... Breast cancer is cancer of breast tissue. ...

Benign tumors are named using -oma as a suffix with the organ name as the root. For instance, a benign tumor of the smooth muscle of the uterus is called leiomyoma (the common name of this frequent tumor is fibroid).

[edit] Adult cancers

In the USA and other developed countries, cancer is presently responsible for about 25% of all deaths.^[3] On a yearly basis, 0.5% of the population is diagnosed with cancer.

The statistics below are for adults in the United States, and will vary substantially in other countries:

Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. ... Breast cancer is cancer of breast tissue. ... Lung cancer is the malignant transformation and expansion of lung tissue, and is the most lethal of all cancers worldwide, responsible for 1. ... Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. ... Bladder cancer refers to any of several types of malignant growths of the urinary bladder. ... Pancreatic cancer (also called cancer of the pancreas) is a malignant tumour within the pancreatic gland. ... Endometrial cancer involves cancerous growth of the endometrium (lining of the uterus). ... Ovarian cancer is a malignant ovarian neoplasm (an abnormal growth located on the ovaries). ... Melanoma is a malignant tumor of melanocytes. ... Leukemia or leukaemia (see spelling differences) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). ... Non-Hodgkin lymphoma is a cancer arising from lymphocytes, a type of white blood cells. ...

[edit] Childhood cancers

Cancer can also occur in young children and adolescents, but it is rare. Some studies have concluded that pediatric cancers, especially leukemia, are on an upward trend.^[4][5]

The age of peak incidence of cancer in children occurs during the first year of life. Leukemia (usually ALL) is the most common infant malignancy (30%), followed by the central nervous system cancers and neuroblastoma. The remainder consists of Wilms' tumor, lymphomas, rhabdomyosarcoma (arising from muscle), retinoblastoma, osteosarcoma and Ewing's sarcoma.^[3] Leukemia or leukaemia (see spelling differences) is a cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). ... Acute lymphoblastic leukemia (ALL), also known as acute lymphocytic leukemia, is a cancer of the white blood cells, characterised by the overproduction and continuous multiplication of malignant and immature white blood cells (referred to as lymphoblasts) in the bone marrow. ... Neuroblastoma is the most common extracranial solid cancer in infancy and childhood. ... Wilms tumor is a neoplasm of the kidneys that typically occurs in children. ... This article is about lymphoma in humans. ... A rhabdomyosarcoma is a type of cancer, specifically a sarcoma (cancer of connective tissues), in which the cancer cells are thought to arise from skeletal muscle progenitors. ... // Retinoblastoma is a cancer of the retina. ... Osteosarcoma is a common primary bone cancer. ... X-Ray of a child with Ewings sarcoma of the tibia Ewings sarcoma is the common name for primitive neuroectodermal tumor. ...

Female and male infants have essentially the same overall cancer incidence rates, but white infants have substantially higher cancer rates than black infants for most cancer types. Relative survival for infants is very good for neuroblastoma, Wilms' tumor and retinoblastoma, and fairly good (80%) for leukemia, but not for most other types of cancer. Wilms tumor is a neoplasm of the kidneys that typically occurs in children. ... // Retinoblastoma is a cancer of the retina. ...

[edit] Causes and pathophysiology

Main article: Carcinogenesis

Cancers are caused by a series of mutations. ...

[edit] Origins of cancer

Cell division or cell proliferation is a physiological process that occurs in almost all tissues and under many circumstances. Normally the balance between proliferation and programmed cell death is tightly regulated to ensure the integrity of organs and tissues. Mutations in DNA that lead to cancer disrupt these orderly processes. This does not adequately cite its references or sources. ... Programmed cell death (PCD) is the deliberate suicide of an unwanted cell in a multicellular organism. ... Biological tissue is a group of cells that perform a similar function. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ...

The uncontrolled and often rapid proliferation of cells can lead to either a benign tumor or a malignant tumor (cancer). Benign tumors do not spread to other parts of the body or invade other tissues, and they are rarely a threat to life unless they extrinsically compress vital structures. Malignant tumors can invade other organs, spread to distant locations (metastasize) and become life-threatening. Benign can refer to any medical condition which, untreated or with symptomatic therapy, will not become life-threatening. ... Tumor or tumour literally means swelling, and is sometimes still used with that meaning. ... In medicine, malignant is a clinical term that is used to describe a clinical course that progresses rapidly to death. ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ...

A few types of cancer in non-humans have been found to be contagious ("parasitic cancer"), such as Sticker's sarcoma, which affects dogs. The closest known analog to this in humans is individuals who have "caught cancer" from tumors hiding inside organ transplants.^[6] A parasitic cancer or transmittable cancer is a cancer cell or cluster of cancer cells that can be transmitted from animal to animal. ... Canine transmissible venereal tumor (CTVT), also called transmissible venereal tumor (TVT), Sticker tumor and infectious sarcoma is a tumor of the dog and other canids that mainly affects the external genitalia, and is transmitted from animal to animal during copulation. ... Trinomial name Canis lupus familiaris The dog Canis lupus is a type of canine, a mammal in the order Carnivora. ...

[edit] Molecular biology

Cancers are caused by a series of mutations. Each mutation alters the behavior of the cell somewhat.

Carcinogenesis, which means the initiation or generation of cancer, is the process of derangement of the rate of cell division due to damage to DNA. Cancer is, ultimately, a disease of genes. In order for cells to start dividing uncontrollably, genes which regulate cell growth must be damaged. Proto-oncogenes are genes which promote cell growth and mitosis, a process of cell division, and tumor suppressor genes discourage cell growth, or temporarily halt cell division in order to carry out DNA repair. Typically, a series of several mutations to these genes are required before a normal cell transforms into a cancer cell. This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Cancers are caused by a series of mutations. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... For other meanings of this term, see gene (disambiguation). ... An oncogene is a gene that can cause a cell to develop into a tumor cell, possibly resulting in cancer. ... Mitosis divides genetic information during cell division. ... A tumor suppressor gene is a gene that reduces the probability that a cell in a multicellular organism will turn into a tumor cell. ... DNA damage resulting in multiple broken chromosomes DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. ... It has been suggested that mutant be merged into this article or section. ...

Proto-oncogenes promote cell growth through a variety of ways. Many can produce hormones, a "chemical messenger" between cells which encourage mitosis, the effect of which depends on the signal transduction of the receiving tissue or cells. Some are responsible for the signal transduction system and signal receptors in cells and tissues themselves, thus controlling the sensitivity to such hormones. They often produce mitogens, or are involved in transcription of DNA in protein synthesis, which creates the proteins and enzymes responsible for producing the products and biochemicals cells use and interact with. Norepinephrine A hormone (from Greek όρμή - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... This article or section does not cite its references or sources. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... A mitogen is a substance that causes a cell to begin dividing. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... Biological and artificial methods for creation of proteins differ significantly. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Biochemistry is the study of the chemical processes and transformations in living organisms. ...

Mutations in proto-oncogenes can modify their expression and function, increasing the amount or activity of the product protein. When this happens, they become oncogenes, and thus cells have a higher chance to divide excessively and uncontrollably. The chance of cancer cannot be reduced by removing proto-oncogenes from the genome as they are critical for growth, repair and homeostasis of the body. It is only when they become mutated that the signals for growth become excessive. Gene expression, or simply expression, is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... An oncogene is a modified gene that increases the malignancy of a tumor cell. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... It has been suggested that Reactive homeostasis be merged into this article or section. ...

Tumor suppressor genes code for anti-proliferation signals and proteins that suppress mitosis and cell growth. Generally tumor suppressors are transcription factors that are activated by cellular stress or DNA damage. Often DNA damage will cause the presence of free-floating genetic material as well as other signs, and will trigger enzymes and pathways which lead to the activation of tumor suppressor genes. The functions of such genes is to arrest the progression of cell cycle in order to carry out DNA repair, preventing mutations from being passed on to daughter cells. Canonical tumor suppressors include the p53 protein, which is a transcription factor activated by many cellular stressors including hypoxia and ultraviolet radiation damage. In molecular biology, a transcription factor is a protein that binds DNA at a specific promoter or enhancer region or site, where it regulates transcription. ... In medical terms, stress is a physical or psychological stimulus that can produce mental or physiological reactions that may lead to illness. ... TP53 bound to a short DNA fragment. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ...

Despite nearly half of all cancers possibly involving alterations in p53, its tumor suppressor function is poorly understood. It is clear it has two functions: one a nuclear role as a transcription factor, and the other a cytoplasmic role in cell cycle and division regulation and apoptosis. TP53 bound to a short DNA fragment. ...

The Warburg effect is the preferential use of glycolysis for energy to sustain cancer growth. p53 has been shown to regulate the shift from the respiratory to the glycolytic pathway. Synthesis of Cytochrome c Oxidase 2 (SCO2) has been recognized as the downstream mediator of this effect. SCO2 is critical for regulating the cytochrome c oxidase complex within the mitochondria, and p53 can disrupt the SCO2 gene. P53 regulation of SCO2 and mitochondrial respiration may provide a possible explanation for the Warburg effect.^[7] The Warburg effect is the inhibition of carbon dioxide fixation, and subsequently photosynthesis, by high oxygen concentrations. ...

However, a mutation can damage the tumor suppressor gene itself, or the signal pathway which activates it, "switching it off". The invariable consequence of this is that DNA repair is hindered or inhibited: DNA damage accumulates without repair, inevitably leading to cancer.

In general, mutations in both types of genes are required for cancer to occur. For example, a mutation limited to one oncogene would be suppressed by normal mitosis control and tumor suppressor genes, which was first hypothesised as the Knudson hypothesis. A mutation to only one tumor suppressor gene would not cause cancer either, due to the presence of many "backup" genes that duplicate its functions. It is only when enough proto-oncogenes have mutated into oncogenes, and enough tumor suppressor genes deactivated or damaged, that the signals for cell growth overwhelm the signals to regulate it, that cell growth quickly spirals out of control. Often, because these genes regulate the processes that prevent most damage to genes themselves, the rate of mutations increase as one gets older, because DNA damage forms a feedback loop. Knudson’s two hit model has recently been challenged by several investigators. Inactivation of one allele of some tumor suppressor genes is sufficient to cause tumors. This phenomenon is called haploinsufficiency and has been demonstrated by a number of experimental approaches. Tumors caused by haploinsufficiency usually have a later age of onset when compared with those by a two hit process.^[8] Look up Hypothesis in Wiktionary, the free dictionary. ... The Knudson hypothesis is the hypothesis that cancer is the result of accumulated mutations to a cells DNA. It was first proposed by Carl O. Nordling in 1953, [1][2] and later formulated by Alfred G. Knudson in 1971. ... In information technology, backup refers to the copying of data so that these additional copies may be restored after a data loss event. ... It has been suggested that this article or section be merged with Feedback loop. ... Haploinsufficiency occurs when a diploid organism only has a single copy of a wild-type gene, with the other copy being inactivated by hereditary mutation or another mechanism. ...

Usually, oncogenes are dominant, as they contain gain-of-function mutations, while mutated tumor suppressors are recessive, as they contain loss-of-function mutations. Each cell has two copies of the same gene, one from each parent, and under most cases gain of function mutation in one copy of a particular proto-oncogene is enough to make that gene a true oncogene, while usually loss of function mutation needs to happen in both copies of a tumor suppressor gene to render that gene completely non-functional. However, cases exist in which one loss of function copy of a tumor suppressor gene can render the other copy non-functional. This phenomenon is called the dominant negative effect and is observed in many p53 mutations. In genetics, the term dominant gene refers to the allele that causes a phenotype that is seen in a heterozygous genotype. ... A gain-of-function mutation is a mutation in DNA that causes the gene to be modified such that the gene product gas a new and abnormal function. ... It has been suggested that this article or section be merged into Dominance relationship. ... A loss-of-function mutation is a mutation in the coding sequence of a gene, which causes the function of the gene product, usually a protein to be either reduced or completely absent. ...

Mutation of tumor suppressor genes that are passed on to the next generation of not merely cells, but their offspring can cause increased likelihoods for cancers to be inherited. Members of these families have increased incidence and decreased latency of multiple tumors. The mode of inheritance of mutant tumor suppressors is that an affected member inherits a defective copy from one parent, and a normal copy from the other. Because mutations in tumor suppressor genes act in a recessive manner (although there are exceptions), the loss of the normal copy creates the cancer phenotype. For instance, individuals who are heterozygous for p53 mutations are often victims of Li-Fraumeni syndrome, and those who are heterozygous for Rb mutations develop retinoblastoma. Similarly, mutations in the APC gene are linked to adenopolyposis colon cancer, with thousands of polyps in colon while young, while mutations in BRCA1 and BRCA2 lead to early onset of breast cancer. In biology, offspring are the product of reproduction, a new organism produced by one or more parents. ... Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. ... An organism is a heterozygote or heterozygous for a gene or trait if it has different alleles at the genes locus for each homologous chromosome. ... Li-Fraumeni syndrome is a rare autosomal dominant hereditary disorder. ... The Retinoblastoma protein, or pRb, is a tumor suppressor protein found to be dysfunctional in a number of types of cancer. ... // Retinoblastoma is a cancer of the retina. ... Familial adenomatous polyposis (FAP) is an inherited condition in which numerous polyps form mainly in the epithelium of the large intestine. ... Familial adenomatous polyposis (FAP) is an inherited condition in which numerous polyps form mainly in the epithelium of the large intestine. ... BRCA 1 (named for breast cancer 1) is a human gene located on the long arm of the 17th chromosome (17q21). ... BRCA2 refers to either a gene (BReast-CAncer susceptibility gene 2, located on human chromosome 13, 13q12-13) or the protein coded for by that gene. ... Breast cancer is cancer of breast tissue. ...

Cancer pathology is ultimately due to the accumulation of DNA mutations that negatively effect expression of tumour suppressor proteins or positively effect the expression of proteins that drive the cell cycle. Substances that cause these mutations are known as mutagens, and mutagens that cause cancers are known as carcinogens. Particular substances have been linked to specific types of cancer. Tobacco smoking is associated with lung cancer. Prolonged exposure to radiation, particularly ultraviolet radiation from the sun, leads to melanoma and other skin malignancies. Breathing asbestos fibers is associated with mesothelioma. In more general terms, chemicals called mutagens and free radicals are known to cause mutations. Other types of mutations can be caused by chronic inflammation, as neutrophil granulocytes secrete free radicals that damage DNA. Chromosomal translocations, such as the Philadelphia chromosome, are a special type of mutation that involve exchanges between different chromosomes. The cigarette is the most common method of smoking tobacco. ... Lung cancer is the malignant transformation and expansion of lung tissue, and is the most lethal of all cancers worldwide, responsible for 1. ... Radiation as used in physics, is energy in the form of waves or particles. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... The Sun is the star at the center of the Solar System. ... Melanoma is a malignant tumor of melanocytes. ... Fibrous asbestos on muscovite Asbestos Asbestos Asbestos (a misapplication of Latin: asbestos quicklime from Greek : a, not and sbestos, extinguishable) describes any of a group of minerals that can be fibrous, many of which are metamorphic and are hydrous magnesium silicates. ... In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... Inflammation is the first response of the immune system to infection or irritation and may be referred to as the Innate immune system and as healthy nor unhealthy on its own: Inflammation helps fight disease, but it comes at the cost of suspending the bodys normal immune and catabolic... This article or section does not cite its references or sources. ... Chromosomal translocation of the 4th and 20th chromosome. ... Philadelphia chromosome or Philadelphia translocation is a specific genetic, chromosomal abnormality that is associated with chronic myelogenous leukemia (CML) and involves an exchange of material between chromosomes 9 and 22. ...

Many mutagens are also carcinogens, but some carcinogens are not mutagens. Examples of carcinogens that are not mutagens include alcohol and estrogen. These are thought to promote cancers through their stimulating effect on the rate of cell mitosis. Faster rates of mitosis increasingly leave less opportunities for repair enzymes to repair damaged DNA during DNA replication, increasing the likelihood of a genetic mistake. A mistake made during mitosis can lead to the daughter cells receiving the wrong number of chromosomes, which leads to aneuploidy and may lead to cancer. In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... The term carcinogen refers to any substance, radionuclide or radiation which is an agent directly involved in the promotion of cancer or in the facilitation of its propagation. ... Functional group of an alcohol molecule. ... Estriol. ... Mitosis divides genetic information during cell division. ... This article or section is in need of attention from an expert on the subject. ... This article is about the biological chromosome. ... Aneuploidy is a change in the number of chromosomes that can lead to a chromosomal disorder. ...

Furthermore, many cancers originate from a viral infection; this is especially true in animals such as birds, but also in humans, as viruses are responsible for 15% of human cancers worldwide. The main viruses associated with human cancers are human papillomavirus, hepatitis B virus, Epstein-Barr virus, and human T-lymphotropic virus. Experimental and epidemiological data imply a causative role for viruses and they appear to be the second most important risk factor for cancer development in humans, exceeded only by tobacco usage.^[9] The mode of virally-induced tumors can be divided into two, acutely-transforming or slowly-transforming. In acutely transforming viruses, the viral particles carry a gene that encodes for an overactive oncogene called viral-oncogene (v-onc), and the infected cell is transformed as soon as v-onc is expressed. In contrast, in slowly-transforming viruses, the virus genome is inserted, especially as viral genome insertion is an obligatory part of retroviruses, near a proto-oncogene in the host genome. The viral promoter or other transcription regulation elements in turn cause overexpression of that proto-oncogene, which in turn induces uncontrolled cellular proliferation. Because viral genome insertion is not specific to proto-oncogenes and the chance of insertion near that proto-oncogene is low, slowly-transforming viruses have very long tumor latency compared to acutely-transforming viruses, which already carry the viral-oncogene. Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus is a microscopic particle (ranging in size from 20 - 300 nm) that can infect the cells of a biological organism. ... An infection is the detrimental colonization of a host organism by a foreign species. ... “Aves” redirects here. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: wise man or knowing man) under the family Hominidae (the great apes). ... HPV redirects here. ... Hepatitis B is a disease of the liver and is caused by the Hepatitis B virus (HBV), a member of the Hepadnavirus family[1] and one of hundreds of unrelated viral species which cause viral hepatitis. ... The Epstein-Barr virus (EBV), also called Human herpesvirus 4 (HHV-4), is a virus of the herpes family (which includes Herpes simplex virus and Cytomegalovirus), and is one of the most common viruses in humans. ... Human T-lymphotropic virus (HTLV) is a human, single-stranded RNA retrovirus that causes T-cell leukemia and T-cell lymphoma in adults and may also be involved in certain demyelinating diseases. ... Genera Alpharetrovirus Betaretrovirus Gammaretrovirus Deltaretrovirus Epsilonretrovirus Lentivirus Spumavirus A retrovirus is any virus belonging to the viral family Retroviridae. ... A promoter is a DNA sequence that contains the information, in the form of DNA sequences, that permits the proper activation or repression of the gene which it controls, i. ...

It is impossible to tell the initial cause for any specific cancer. However, with the help of molecular biological techniques, it is possible to characterize the mutations or chromosomal aberrations within a tumor, and rapid progress is being made in the field of predicting prognosis based on the spectrum of mutations in some cases. For example, some tumors have a defective p53 gene. This mutation is associated with poor prognosis, since those tumor cells are less likely to go into apoptosis or programmed cell death when damaged by therapy. Telomerase mutations remove additional barriers, extending the number of times a cell can divide. Other mutations enable the tumor to grow new blood vessels to provide more nutrients, or to metastasize, spreading to other parts of the body. Molecular biology is the study of biology at a molecular level. ... Prognosis (older Greek πρόγνωσις, modern Greek πρόγνωση - literally fore-knowing, foreseeing) is a medical term denoting the doctors prediction of how a patients disease will progress, and whether there is chance of recovery. ... A cell undergoing apoptosis. ... Programmed cell death (PCD) is the deliberate suicide of an unwanted cell in a multicellular organism. ... Telomerase is an enzyme that adds specific DNA sequence repeats (TTAGGG in all vertebrates) to the 3 (three prime) end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. ... Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ...

Malignant tumor cells have distinct properties:

• evading apoptosis
• unlimited growth potential (immortalitization) due to overabundance of telomerase
• self-sufficiency of growth factors
• insensitivity to anti-growth factors
• increased cell division rate
• altered ability to differentiate
• no ability for contact inhibition
• ability to invade neighbouring tissues
• ability to build metastases at distant sites
• ability to promote blood vessel growth (angiogenesis)

A cell that degenerates into a tumor cell does not usually acquire all these properties at once, but its descendant cells are selected to build them. This process is called clonal evolution. A first step in the development of a tumor cell is usually a small change in the DNA, often a point mutation, which leads to a genetic instability of the cell. The instability can increase to a point where the cell loses whole chromosomes, or has multiple copies of several. Also, the DNA methylation pattern of the cell changes, activating and deactivating genes without the usual regulation. Cells that divide at a high rate, such as epithelials, show a higher risk of becoming tumor cells than those which divide less, for example neurons. A cell undergoing apoptosis. ... Telomerase is an enzyme that adds specific DNA sequence repeats (TTAGGG in all vertebrates) to the 3 (three prime) end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. ... Growth factor is a protein that acts as a signaling molecule between cells (like cytokines and hormones) that attaches to specific receptors on the surface of a target cell and promotes differentiation and maturation of these cells. ... This does not adequately cite its references or sources. ... Embryonic stem cells differentiate into cells in various body organs. ... The loss of cell division when one cell contact with another cell when optimum size and volume of the tissue has been formed. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. ... Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. ... Darwins illustrations of beak variation in the finches of the Galápagos Islands, which hold 13 closely related species that differ most markedly in the shape of their beaks. ... A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. ... THERE ARE NOW 30 CHROMOSOMES!!!!!! Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... DNA methylation is a type of chemical modification of DNA that can be inherited without changing the DNA sequence. ... For other meanings of this term, see gene (disambiguation). ... In zootomy, epithelium is a tissue composed of a layer of cells. ... Drawing by Santiago Ramón y Cajal of neurons in the pigeon cerebellum. ...

[