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Radiation hormesis is the conjecture that a low level of ionizing radiation (i.e., near the level of Earth's natural background radiation) helps "immunize" cells against DNA damage from other causes (such as free radicals or larger doses of ionizing radiation), and decreases the risk of cancer. The theory proposes that such low levels activate ...
In a few cases, only one cause exists: for example, the virus HHV-8 causes all Kaposi's sarcomas. However, with the help of cancer epidemiology techniques and information, it is possible to produce an estimate of a likely cause in many more situations. For example, lung cancer has several causes, including tobacco use and radon gas.
Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure.
Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure.
Damage to DNA can be caused by exposure to radiation, chemicals, and other environmental sources, but mutations also accumulate naturally over time through uncorrected errors in DNA transcription, making age another risk factor. [20] Oncoviruses can cause certain types of cancer, and genetics are also known to play a role. [21]
Ulceration can cause bleeding that can lead to symptoms such as coughing up blood (lung cancer), anemia or rectal bleeding (colon cancer), blood in the urine (bladder cancer), or abnormal vaginal bleeding (endometrial or cervical cancer). Although localized pain may occur in advanced cancer, the initial tumor is usually painless.
This represents about 3% of the almost seven million deaths due to cancer that year, and about 0.35% of all deaths from any cause. [79] Of the sixteen separate sites the body compared, leukemia was the 12th most common class of neoplastic disease and the 11th most common cause of cancer-related death. [ 79 ]
UV light from solar radiation causes DNA damage that is important in melanoma. [21] Helicobacter pylori infection produces high levels of reactive oxygen species that damage DNA and contributes to gastric cancer. [22] Bile acids, at high levels in the colons of humans eating a high fat diet, also cause DNA damage and contribute to colon cancer ...