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| I'M GONNA RAPE YOUR MOTHER IN HER ASS | |||
| {{otheruses}} | |||
| ]; cancer cells, however, avoid apoptosis.]] | |||
| '''Cancer''' is a class of ]s characterized by uncontrolled ] division and the ability of these cells to invade other ], either by direct growth into adjacent tissue (''invasion'') or by migration of cells to distant sites (''metastasis''). This unregulated growth is caused by a series of acquired or inherited ]s to ] within cells, damaging ] information that define the cell functions and removing normal control of cell division. These invasive tissues are said to be ]. The word '']'' ("swelling" in ]) refers to any mass of abnormal tissue, but may be either malignant (cancerous) or '']'' (noncancerous). | |||
| Cancer can cause many different symptoms, depending on the site and character of the malignancy and whether there is ] (spread). A definitive diagnosis usually requires the microscopic examination of tissue in the form of a ]. Once diagnosed, cancer is usually treated with ], ] and/or ]. | |||
| If untreated, most cancers eventually cause ]; cancer is one of the leading causes of death in ]. Most cancers can be treated and many cured, especially if treatment begins early. | |||
| Many forms of cancer are associated with environmental factors that are avoidable. ] leads to more cancers than any other environmental factor. | |||
| ==Diagnosing cancer== | |||
| Most cancers are initially recognized either because signs or symptoms appear or through screening. Neither of these lead to a definitive diagnosis, which usually requires a biopsy. Some cancers are discovered accidentally during medical evaluation of an unrelated problem. | |||
| ===Signs and symptoms=== | |||
| Roughly, cancer symptoms can be divided into three groups: | |||
| * ''Local symptoms'': unusual lumps or swelling ('']''), ] (bleeding), ] and/or ]ation. Compression of surrounding tissues may cause symptoms such as ]. | |||
| * ''Symptoms of ] (spreading)'': enlarged ]s, ] and ], ] (enlarged ]), bone pain, ] of affected bones and ] symptoms. Although advanced cancer may cause ], it is usually not the first symptom. | |||
| * ''Systemic symptoms'': ], ] and ] (wasting), excessive ] (]), ] and specific ], i.e. specific conditions that are due to an active cancer, such as ] or hormonal changes. | |||
| Every single item in the above list can be caused by a variety of conditions (a list of which is referred to as the ]). Cancer may be a common or uncommon cause of each item. | |||
| ===Biopsy=== | |||
| A cancer may be suspected for a variety of reasons, but the the definitive diagnosis of most malignancies must be confirmed by microscopic examination of the cancerous cells by a ]. The procedure of obtaining cells and/or pieces of tissue, and their examination, is referred to as a ]. The tissue diagnosis indicates the type of cell that is proliferating, its severity (degree of ]), and its extent and size. ] and ] tests may provide information about future behavior of the cancer (prognosis) and best treatment. | |||
| Most cancers can be cured if entirely removed. Sometimes this can be accomplished by the biopsy procedure. When the whole mass of abnormal tissue (the "lesion") is removed, the borders of the sample are examined closely to see if all malignant tissue has truly been excised. This is especially common with cancers of the skin. | |||
| The nature of the biopsy depends on the organ that is sampled. Many biopsies (such as those of the skin, breast or liver) can happen on an outpatient basis. Biopsies of other organs are performed under ] and require ]. | |||
| ===Screening=== | |||
| Cancer screening is a test to detect unsuspected cancers in the population. Screening tests suitable for large numbers of healthy people must be relatively affordable, safe, noninvasive procedures with acceptably low rates of false positive results. If signs of cancer are detected, more definitive and invasive followup tests are performed to confirm the diagnosis. | |||
| Screening for cancer can lead to earlier diagnosis. Early diagnosis may lead to extended life. A number of different screening tests have been developed. Breast cancer screening can be done by ]. Screening by regular ]s detects tumors even earlier than self-examination, and many countries use it to systematic screen all middle-aged women. Colorectal cancer can be detected through ]ing and ], which reduces both colon cancer incidence and mortality, presumably through the detection and removal of premalignant polyps. Similarly, cervical cytology testing (using the ]) leads to the identification and excision of precancerous lesions. Over time, such testing has been followed by a dramatic reduction of ] incidence and mortality. ] is recommended for men beginning at the age of 15 years to detect ]. Prostate cancer can be screened for by a ] along with ] (PSA) blood testing. | |||
| Screening for cancer is controversial in cases when it is not yet known if the test actually saves lives. The controversy arises when it is not clear if the benefits of screening outweigh the risks of follow-up diagnostic tests and cancer treatments. For example: when screening for ], the ] test may detect small cancers that would never become life threatening, but once detected will lead to treatment. This situation, called ], puts men at risk for complications from unnecessary treatment such as surgery or radiation. Followup procedures used to diagnose prostate cancer (]) may cause side effects, including bleeding and infection. Prostate cancer treatment may cause ] (inability to control urine flow) and ] (erections inadequate for intercourse). Similarly, for ], there have recently been criticisms that breast screening programs in some countries cause more problems than they solve. This is because screening of women in the general population will result in a large number of women with false positive results which require extensive follow-up investigations to exclude cancer, leading to having a high number-to-treat (or number-to-screen) to prevent or catch a single case of breast cancer early. | |||
| Cervical cancer screening via the ] has the best cost-benefit profile of all the forms of cancer screening from a public health perspective as, as a cancer, it has clear risk factors (sexual contact), the natural progression of cervical cancer is that it normally spreads slowly over a number of years therefore giving more time for the screening program to catch it early and the test itself is easy to perform and relatively cheap. | |||
| For these reasons, it is important that the benefits and risks of diagnostic procedures and treatment be taken into account when considering whether to undertake cancer screening. | |||
| Use of ] to search for cancer in people without clear symptoms is similarly marred with problems. There is a significant risk of detection of what has been recently called an '']'' - a benign lesion that may be interpreted as a malignancy and be subjected to potentially dangerous investigations. | |||
| ==Types of cancer== | |||
| Cancer cells within a tumor are the ]s of a single cell, even after it has metastasized. Hence, a cancer can be classified by the type of cell in which it originates and by the location of the cell. | |||
| ]s originate in ]s (e.g. the ] or ]s). ], such as ] and ], arise from ] and ]. ] arises from ], ] or ]. ] arises in ]s. ] begins within ]s. | |||
| ===Adult cancers=== | |||
| In the USA and other developed countries, cancer is presently responsible for about 25% of all deaths{{fn|1}}. On a yearly basis, 0.5% of the population is diagnosed with cancer. | |||
| For adult males in the ], the most common cancers are ] (33% of all cancer cases), ] (13%), ] (10%), ] (7%) and cutaneous ] (5%). As a cause of death lung cancer is the most common (31%) cause, followed by prostate cancer (10%), colorectal cancer (10%), ] (5%) and leukemia (4%){{fn|1}}. | |||
| For adult females in the ], ] is the most common cancer (32% of all cancer cases) followed by lung cancer (12%), colorectal cancer (11%), ] (6%, uterus) and ] (4%). By cause of death, lung cancer is again the most common (27% of all cancer deaths), followed by breast cancer (15%), colorectal cancer (10%), ] (6%) and pancreatic cancer (6%){{fn|1}}. | |||
| These statistics vary substantially in other countries. | |||
| Other cancers not mentioned: | |||
| * Epithelial tumors: ] (this is in fact the most common cancer but often not classified as such in health statistics), ], ], ], ] (in the ]), ], ] (in the ]s), ], many ]s, and ]. | |||
| * Hematological malignancies (] and ]): ], ], ]. | |||
| * Sarcomas: ] (in ]), ] - in ]s, (including benign ]). | |||
| * Miscellaneous origin: ]s, ]s (GIST), ] (in the ] or ]) and ]s | |||
| ===Childhood cancers=== | |||
| Cancer can also occur in young children and adolescents. Here, the aberrant genetic processes that fail to safeguard against the clonal proliferation of cells with unregulated growth potential occur early in life and can progress quickly. | |||
| The age of peak incidence of cancer in children occurs during the first year of life. ] is the most common infant malignancy (30%), followed by the central nervous system cancers and ]. The remainder consists of ], ]s, ] (arising from muscle), ], ] and ]{{fn|1}}. | |||
| Female infants 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, ] and ], but not for most other types of cancer. | |||
| ==Causes and pathophysiology== | |||
| {{main|Carcinogenesis}} | |||
| ===Origins of cancer=== | |||
| ] (''proliferation'') is a physiological process that occurs in almost all tissues and under many circumstances. Normally the balance between proliferation and cell death is tightly regulated to ensure the integrity of organs and ]. Mutations in ] that lead to cancer disrupt these orderly processes. | |||
| The uncontrolled and often rapid proliferation of cells can lead to either a ] ] or a ] 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 (]) and become life-threatening. | |||
| ===Molecular biology=== | |||
| ] | |||
| '']'' (meaning literally, the creation of cancer) is the process of derangement of the rate of cell division due to damage to ]. | |||
| Cancer is, ultimately, a disease of ]s. Typically, a series of several ]s is required before a normal cell transforms into a cancer cell. The process involves both ]s and ]s. Proto-oncogenes are involved in ] by coding for a ] "messenger", produced when a cell undergoes ]. These messengers, send signals based on the amount of them present to the cell or other cells, telling them to undergo ], in order divide and reproduce. When mutated, they become ]s and ] the signals to divide, and thus cells have a higher chance to divide excessively. Frustratingly, the chance of cancer cannot be reduced by removing proto-oncogenes from the human genome as they are critical for growth, repair and ] of the body. It is only when they become mutated, that the signals for growth become excessive. | |||
| Tumor suppressor genes code for chemical messengers that command cells to slow or stop mitosis in order to allow ]. This is done by special ] which detect any mutation or damage to DNA, such that the mistake is not carried on to the next generation. Tumor suppressor genes are usually triggered by signals that DNA damage has occurred. In addition to inhibiting mitosis, they can code for such enzymes themselves, or sending signals to activate such enzymes. However, a mutation can damage the tumor suppressor gene itself, or the signal pathway which activate 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 (the ] or 1-2-hit hypothesis) and tumor suppressor genes. A mutation to only one tumor suppressor gene would not cause cancer either, due to the presence of many "]" 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. | |||
| Mutations can have various causes. Particular causes have been linked to specific types of cancer. ] is associated with ]. Prolonged exposure to ], particularly ] from the ], leads to ] and other skin malignancies. Breathing ] fibers is associated with ]. In more general terms, chemicals called ]s and ]s are known to cause mutations. Other types of mutations can be caused by chronic ], as ]s secrete free radicals that damage DNA. ]s, such as the ], are a special type of mutation that involve exchanges between different chromosomes. | |||
| Many ]s are also ]s, but some carcinogens are not mutagens. Examples of carcinogens that are not mutagens include ] and ]. These are thought to promote cancers through their stimulating effect on the rate cellular ]. Faster rates of mitosis increasingly leave less window space for repair enzymes to repair damaged DNA during ], increasingly the likelihood of a genetic mistake. A mistake made during mitosis can lead to the daughter cells receiving the wrong number of ], which leads to ] and may lead to cancer. | |||
| Mutations can also be inherited. Inheriting certain mutations in the ] gene renders a woman much more likely to develop ] and ], mutations in the ] gene predispose to ], and those in the ] gene lead to ]. | |||
| Some types of viruses can cause mutations. They play a role in about 15% of all cancers. ''Tumor viruses'', such as some ]es, ]es and ]es, usually carry an oncogene or a gene inhibits normal tumor suppression in their ]. | |||
| It is impossible to tell the initial cause for any specific cancer. However, with the help of ] 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 ] based on the spectrum of mutations in some cases. For example, up to half of all tumors have a defective ] gene, a tumor suppressor gene also known as "the guardian of the genome". This mutation is associated with poor prognosis, since those tumor cells are less likely to go into ] (programmed cell death) when damaged by therapy. ] mutations remove additional barriers, extending the number of times a cell can divide. Other mutations enable the tumor to ] to provide more nutrients, or to metastasize, spreading to other parts of the body. | |||
| <!-- more elaboration here, maybe fork off to another article? --> | |||
| Malignant tumors cells have distinct properties: | |||
| * evading ] | |||
| * unlimited growth potential (immortalitization) | |||
| * self-sufficiency of ]s | |||
| * insensitivity to anti-growth factors | |||
| * increased ] rate | |||
| * altered ability to ] | |||
| * no ability for ] | |||
| * ability to invade neighbouring ]s | |||
| * ability to build ] at distant sites | |||
| * ability to promote blood vessel growth (]) | |||
| A cell that degenerates into a tumor cell does not usually acquire all these properties at once, but its descendant cells are ] to build them. This process is called ]. A first step in the development of a tumor cell is usually a small change in the DNA, often a ], which leads to a genetic instability of the cell. The instability can increase to a point where the cell loses whole ]s, or has multiple copies of several. Also, the ] pattern of the cell changes, activating and deactivating ]s without the usual control. Cells that divide at a high rate, such as ]s, show a higher risk of becoming tumor cells than those which divide less, for example ]s. | |||
| ===Morphology=== | |||
| ] | |||
| Cancer tissue has a distinctive appearance under the ]. Among the distinguishing traits are a large number of dividing cells, variation in ] size and shape, variation in cell size and shape, loss of specialized cell features, loss of normal tissue organization, and a poorly defined tumor boundary. ] and other molecular methods may characterise specific markers on tumor cells, which may aid in diagnosis and prognosis. | |||
| Biopsy and microscopical examination can also distinguish between malignancy and ], which refers to tissue growth based on an excessive rate of cell division, leading to a larger than usual number of cells but with a normal orderly arrangement of cells within the tissue. This process is considered reversible. Hyperplasia can be a normal tissue response to an irritating stimulus, for example ]. | |||
| ] is an abnormal type of excessive cell proliferation characterized by loss of normal tissue arrangement and cell structure. Often such cells revert back to normal behavior, but occasionally, they gradually become malignant. | |||
| The most severe cases of dysplasia are referred to as "]." In Latin, the term "in situ" means "in place", so carcinoma in situ refers to an uncontrolled growth of cells that remains in the original location and shows no propensity to invade other tissues. Nevertheless, carcinoma in situ may develop into an invasive malignancy and is usually removed surgically, if possible. | |||
| ===Heredity=== | |||
| Most forms of cancer are "sporadic", and have no basis in heredity. There are, however, a number of recognised ]s of cancer with a hereditary component. Examples are: | |||
| * ] and ] in female carriers of ] | |||
| * tumors of various endocrine organs in ] (MEN types 1, 2a, 2b) | |||
| * ] (various tumors such as ], breast cancer, ], ]s) due to mutations of ] | |||
| * ] (]s and colonic polyposis) | |||
| * ] an inherited mutation of the ''APC'' gene that leads to early onset of ]. | |||
| ===Environment and diet=== | |||
| ] | |||
| The most consistent finding, over decades of research, is the strong association between ] use and cancers of many sites. Hundreds of epidemiological studies have confirmed this association. Further support comes from the fact that ] death rates in the United States have mirrored ] patterns, with increases in smoking followed by dramatic increases in lung cancer death rates and, more recently, decreases in smoking followed by decreases in lung cancer death rates in men. Up to half of all cancer cases can be attributed to smoking, diet, and environmental pollution. | |||
| ==Treatment of cancer== | |||
| Cancer can be treated by ], ], ], ] or other methods. The choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient (]). A number of ]s are also under development. | |||
| Complete removal of the cancer without damage to the rest of the body is the goal of treatment. Sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to spread to distant sites by microscopic metastasis often limits its effectiveness. The effectiveness of chemotherapy is often limited by toxicity to other tissues in the body. Radiation can also cause damage to normal tissue. | |||
| Because "cancer" refers to a class of diseases, it is unlikely that there will ever be a single "cure for cancer" any more than there will be a single treatment for all ]s. | |||
| ===Surgery=== | |||
| If the tumor is localized, ] is often the preferred treatment. Example procedures include ] for breast cancer and ] for prostate cancer. The goal of the surgery can be either the removal of only the tumor, or the entire organ. Since a single cancer cell can grow into a sizable tumor, removing only the tumor leads to a greater chance of recurrence. A margin of healthy tissue is often resected to make sure all cancerous tissue is removed. | |||
| In addition to removal of the primary tumor, surgery is often necessary for staging, e.g. determining the extent of the disease and whether there has been ] to regional ]s. Staging determines the prognosis and the need for adjuvant therapy. | |||
| Occasionally, surgery is necessary to control symptoms, such as ] or ]. This is referred to as ]. | |||
| ===Chemotherapy=== | |||
| ] is the treatment of cancer with ] ("anticancer drugs") that can destroy cancer cells. It interferes with cell division in various possible ways, e.g. with the duplication of ] or the separation of newly formed ]s. Most forms of chemotherapy target all rapidly dividing cells and are not specific for cancer cells. Hence, chemotherapy has the potential to harm healthy tissue, especially those tissues that have a high replacement rate (e.g. intestinal lining). These cells usually repair themselves after chemotherapy. | |||
| Because some drugs work better together than alone, two or more drugs are often given at the same time. This is called "combination chemotherapy"; most chemotherapy regimens are given in a combination. | |||
| ===Immunotherapy=== | |||
| ] is the use of ] mechanisms against tumors. These are used in various forms of cancer, such as ] (]/Herceptin®) but also in ] (]/Mylotarg®). The agents are ] directed against proteins that are characteristic to the cells of the cancer in question, or ]s that modulate the immune system's response. | |||
| ===Radiation therapy=== | |||
| ] (also called radiotherapy, X-ray therapy, or irradiation) is the use of a certain type of energy (called ]) to kill cancer cells and shrink tumors. Radiation therapy injures or destroys cells in the area being treated (the "target tissue") by damaging their genetic material, making it impossible for these cells to continue to grow and divide. Although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly. The goal of radiation therapy is to damage as many cancer cells as possible, while limiting harm to nearby healthy tissue. | |||
| Radiation therapy may be used to treat almost every type of solid tumor, including cancers of the brain, breast, cervix, larynx, lung, pancreas, prostate, skin, spine, stomach, uterus, or soft tissue sarcomas. Radiation can also be used to treat leukemia and lymphoma (cancers of the blood-forming cells and lymphatic system, respectively). Radiation dose to each site depends on a number of factors, including the type of cancer and whether there are tissues and organs nearby that may be damaged by radiation. | |||
| ===Hormonal suppression=== | |||
| The growth of nearly all tissues, including cancers, can be accelerated or inhibited by providing or blocking certain hormones. This allows an additional method of treatment for many cancers. Common examples of hormone-sensitive tumors include certain types of breast, prostate, and ]s. Removing or blocking ], ], or ], respectively, is often an important additional treatment. | |||
| ===Treatment trials=== | |||
| ]s, also called research studies, test new treatments in people with cancer. The goal of this research is to find better ways to treat cancer and help cancer patients. Clinical trials test many types of treatment such as new drugs, new approaches to surgery or radiation therapy, new combinations of treatments, or new methods such as ]. | |||
| A clinical trial is one of the final stages of a long and careful cancer research process. The search for new treatments begins in the laboratory, where scientists first develop and test new ideas. If an approach seems promising, the next step may be testing a treatment in animals to see how it affects cancer in a living being and whether it has harmful effects. Of course, treatments that work well in the lab or in animals do not always work well in people. Studies are done with cancer patients to find out whether promising treatments are safe and effective. | |||
| Patients who take part may be helped personally by the treatment(s) they receive. They get up-to-date care from cancer experts, and they receive either a new treatment being tested or the best available standard treatment for their cancer. Of course, there is no guarantee that a new treatment being tested or a standard treatment will produce good results. New treatments also may have unknown risks, but if a new treatment proves effective or more effective than standard treatment, study patients who receive it may be among the first to benefit. | |||
| ===Complementary and alternative medicine=== | |||
| ] (CAM) treatments are the diverse group of medical and health care systems, practices, and products that are not presently considered to be effective by the standards of conventional medicine. Some non-conventional treatment methods are used to "complement" conventional treatment, to provide comfort or lift the spirits of the patient, while others are offered as alternatives to be used instead of conventional treatments in hope of curing the cancer. | |||
| Common '''complementary''' measures include ] or psychological approaches such as "imaging." Many people feel these approaches benefit them, but most have not been scientifically proven and therefore face skepticism. | |||
| A wide range of '''alternative''' treatments have been offered for cancer over the last century. The appeal of alternative cures arises from the daunting risks, costs, or potential side effects of many conventional treatments, or in the limited prospect for cure. Proponents of these therapies are unable or unwilling to demonstrate effectiveness by conventional criteria. Alternative treatments have included special diets or dietary supplements (e.g., the "grape diet" or megavitamin therapy), electrical devices (e.g., "zappers"), specially formulated compounds (e.g., laetrile), unconventional use of conventional drugs (e.g., insulin), purges or enemas, or physical manipulations of the body. Some of these treatments meet all the criteria for ] or ]. Collectively they are referred to by skeptics as ]. An extensive, explanatory catalog of these treatments is available at ] . Almost all physicians recommend against using these modalities as sole treatment for potentially fatal conditions such as cancer. | |||
| ==Epidemiology== | |||
| In some Western countries, such as the USA{{fn|1}} and the UK{{fn|2}}, cancer is overtaking ] as the leading cause of death. In many ] countries cancer incidence (insofar as this can be measured) appears much lower, most likely because of the higher death rates due to infectious disease or injury. With the increased control over ] and ] in some Third World countries, incidence of cancer is expected to rise; this is termed the ] in ] terminology. | |||
| Cancer epidemiology closely mirrors risk factor spread in various countries. ] (liver cancer) is rare in the West but is the main cancer in ] and neighboring countries, most likely due to the endemic presence of ] in that population. Similarly, with ] becoming more common in various Third World countries, lung cancer incidence has increased in a parallel fashion. | |||
| ==Prevention== | |||
| Cancer prevention is defined as active measures to decrease the incidence of cancer. This can be accomplished by avoiding ]s or altering their ], pursuing a lifestyle or diet that modifies cancer-causing factors and/or medical intervention (], treatment of premalignant lesions). | |||
| Much of the promise for cancer prevention comes from observational epidemiologic studies that show associations between modifiable life style factors or environmental exposures and specific cancers. Evidence is now emerging from randomized controlled trials designed to test whether interventions suggested by the epidemiologic studies, as well as leads based on laboratory research, actually result in reduced cancer incidence and mortality. | |||
| Examples of modifiable cancer risk include ] consumption (associated with increased risk of oral, esophageal, breast, and other cancers), physical inactivity (associated with increased risk of colon, breast, and possibly other cancers), and being ] (associated with colon, breast, endometrial, and possibly other cancers). Based on epidemiologic evidence, it is now thought that avoiding excessive alcohol consumption, being physically active, and maintaining recommended body weight may all contribute to reductions in risk of certain cancers; however, compared with tobacco exposure, the magnitude of effect is modest or small and the strength of evidence is often weaker. Other lifestyle and environmental factors known to affect cancer risk (either beneficially or detrimentally) include certain sexual and reproductive practices, the use of exogenous hormones, exposure to ionizing radiation and ultraviolet radiation, certain occupational and chemical exposures, and infectious agents. | |||
| ===Diet and cancer=== | |||
| The consensus on diet and cancer is that ] increases the risk of acquiring cancer. Particular dietary practices often explain differences in cancer incidence in different countries (e.g. ] is more common in ], while ] is more common in the United States). Studies have shown that immigrants develop the risk of their new country, suggesting a link between diet and cancer rather than a genetic basis. | |||
| Despite frequent reports of particular substances (including foods) having a beneficial or detrimental effect on cancer risk, few of these have an established link to cancer. These reports are often based on studies in cultured cell media or animals. Public health recommendations cannot be made on the basis of these studies until they have been validated in an observational (or occasionally a prospective interventional) trial in humans. | |||
| The case of ] provides an example of the necessity of randomized clinical trials. ] studying both diet and serum levels observed that high levels of ], a precursor to ], were associated with a protective effect, reducing the risk of cancer. This effect was particularly strong in lung cancer. This hypothesis led to a series of large randomized trials conducted in both ] and the ] (CARET study) during the 1980s and 1990s. This study provided about 80,000 smokers or former smokers with daily supplements of beta-carotene or ]s. Contrary to expectation, these tests found no benefit of ] supplementation in reducing lung cancer incidence and mortality. In fact, the risk of lung cancer was slightly, but significantly, increased in smokers, leading to an early termination of the study{{fn|3}}. | |||
| ===Other chemoprevention agents=== | |||
| Daily use of ], a selective ] modulator, for up to 5 years, has been demonstrated to reduce the risk of developing ] in high-risk women by about 50%. ] also has been shown to reduce risk of second primary tumors among patients with primary ]. ], a ], has been shown to lower the risk of prostate cancer. Other examples of drugs that show promise for chemoprevention include ] (which inhibit a ] enzyme involved in the synthesis of proinflammatory ]s). | |||
| ===Cancer vaccines=== | |||
| Considerable research effort is now devoted to the development of ]s (to prevent infection by oncogenic infectious agents, as well as to mount an immune response against cancer-specific ]s) and to potential venues for ] for individuals with genetic mutations or polymorphisms that put them at high risk of cancer. No cancer vaccines are presently in use, and most of the research is still in its initial stages. | |||
| ===Genetic testing=== | |||
| ] for high-risk individuals, with enhanced surveillance or prophylactic surgery for those who test positive, is already available for certain types of cancer, including breast and ovarian cancer. | |||
| ==Coping with cancer== | |||
| Many local organizations offer a variety of practical and support services to people with cancer. Support can take the form of ], ], advice, financial assistance, transportation to and from treatment, or information about cancer. Neighborhood organizations, local health care providers, or area hospitals are a good place to start looking. | |||
| While some people are reluctant to seek counseling, studies show that having someone to talk to reduces stress and helps people both mentally and physically. Counseling can also provide emotional support to cancer patients and help them better understand their illness. Different types of counseling include individual, group, family, self-help (sometimes called peer counseling), bereavement, patient-to-patient, and sexuality. | |||
| Many governmental and charitable organizations have been established to help patients cope with cancer. These organizations often are involved in cancer prevention, cancer treatment, and cancer research. Examples include: ], ], ], ], ] and the ] (US). | |||
| ==Social impact== | |||
| Cancer has a reputation for being a deadly disease. While this certainly applies to certain particular types, this is otherwise a generalization. Some types of cancer have a prognosis that is substantially better than nonmalignant diseases such as ] and ]. | |||
| Progressive and disseminated malignant disease has a substantial impact on a cancer patient's quality of life, and many cancer treatments (such as ]) may have severe side-effects. In the advanced stages of cancer, many patients need extensive care, affecting family members and friends. ] solutions may include permanent or "respite" ] nursing. | |||
| ==Cancer research== | |||
| ] is the intense scientific effort to understand disease processes and discover possible therapies. While understanding of cancer has ] since the last decades of the 20th century, radically new therapies are only discovered and introduced gradually. | |||
| Inhibitors of tyrosine kinases (] and ]) in the late 1990s were considered a major breakthrough; these interfere specifically with tumor-specific proteins. ] have proven to be another major step in oncological treatment. | |||
| ==See also== | |||
| {{wiktionary}} | |||
| {{Commons|Cancer (illness)}} | |||
| * ] | |||
| * ] | |||
| * ] | |||
| * ] | |||
| ==References== | |||
| *{{fnb|1}} Jemal A, Murray T, Ward E, Samuels A, Tiwari RC, Ghafoor A, Feuer EJ, Thun MJ. ''Cancer statistics, 2005.'' CA Cancer J Clin 2005;55:10-30. . PMID 15661684. | |||
| *{{fnb|2}} (9 November, 2000). ''BBC News online''. Retrieved 2005-01-29. | |||
| *{{fnb|3}} | |||
| ==External links== | |||
| *{{wikicitiespar|cancer|cancer|Cancer Help Infosite}} | |||
| * A review of worldwide strategies for the prevention and treatment of cancer. | |||
| * Government organization for research and treatment | |||
| * Patient advocate group | |||
| * Textbook | |||
| * - has free guidelines for professionals and many pages of quality information for patients with all types of cancers | |||
| * - purports to be "the leading charity in the field of diet, nutrition and cancer", supporting research into dietary methods for the prevention and treatment of cancer in addition to offering educational resources. | |||
| * - Association of Cancer Online Resources | |||
| * from ] - provides links to news, general sites, diagnosis, treatment and alternative therapies, clinical trials, research, related issues, organizations, other MedlinePlus and , and more. Also, links to pre-formulated searches of the ]/PubMed database for recent research articles. | |||
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Revision as of 13:09, 25 June 2005
I'M GONNA RAPE YOUR MOTHER IN HER ASS