Cancers associated with high-dose exposure include leukemia, breast, bladder, colon, liver, lung, esophagus, ovary, multiple myeloma, and stomach cancer. Epidemiological studies provide the necessary data to quantify cancer risks based on dose and to establish radiation protection standards. Leukemia and most solid cancers have been linked to radiation. Most solid cancer data are reasonably well described by linear dose response functions, although there may be a decrease in risks with very high doses.
People exposed early in life have especially high relative risks for many types of cancer, and the risk of solid, radiation-related cancer seems to persist throughout life. Most side effects go away after treatment. However, some continue, return, or develop later. These effects are called long-term or late effects.
A possible late effect is the development of a second cancer. This is a new type of cancer that develops because of the original cancer treatment. The risk of this late effect is low. And the risk is usually lower than the benefit of treating the first cancer.
Nakamura explained that radiation-induced cancers can occur in pediatric cancer survivors, who are often given intensive chemoradiation therapy. They can also occur in adult cancer survivors. Radiation-induced cancers can arise at a wide range of intervals after cancer treatment, from several years to decades. While these cancers most commonly occur in a wide variety of solid tissues, blood cancers can also arise after radiation therapy, he said.
Epidemiological studies of people exposed to ionizing radiation provide a wealth of information about cancer risks in humans. In addition to the breast cancer studies discussed above, case-control studies of breast cancer were conducted in patients treated for malignant disease. Side effects patients experience after radiation therapy may depend on the cancer it is being used for. This article summarizes the main findings of epidemiological studies on cancer risks in relation to exposure to ionizing radiation.
Six cohorts with information on smoking compared risks in smokers and never smokers and confirmed a significant response to lung cancer exposure in those who had never smoked (there were 64 deaths from lung cancer in these subjects). Approximately 11% of solid cancers that occurred in survivors with doses of 0.005 Gy or more were attributed to radiation (Preston et al. Updating data on childhood cancer survivors will assess the risks of a second cancer as these survivors are followed up into adulthood Radiation of certain wavelengths, called ionizing radiation, has enough energy to damage DNA and cause cancer. Harris reviewed several sources of radiation exposure in everyday life, including non-ionizing sources such as cell phones and Wi-Fi, and ionizing sources such as living near a nuclear power plant and exposure to cosmic radiation through air travel.
Recent risk assessments conducted by the Committee to Assessing Health Risks from Exposure to Low Levels of Ionizing Radiation (BEIR VII) (NRC 200) and by UNSCEAR (200) make intensive use of cancer incidence data from the LSS cohort. It's not possible to predict who might have a second cancer, but sometimes cancer treatment can put a person at higher risk for a second cancer. For more information, see the fact sheets on Accidents at Nuclear Power Plants and Cancer Risk and Computed Tomography (CT) and Cancer Scans. In patients with hereditary retinoblastoma, radiation seems to increase the already high risks of sarcomas and other types of cancer (Wong et al.
Studies of patients internally exposed to thorotrasystus and radium (HIGH-LET) have also been conducted and used to estimate risks of liver and bone cancer, respectively, by alpha emitters (NRC 1988, National Council on Radiation Protection and Measurements 2001, UNSCEAR 200. .
