Diagnostic X-ray procedures and risk of leukemia, lymphoma, and multiple myeloma

Article Abstract:

A recent report from a committee of the National Academy of Sciences indicated that the lifetime cancer risk from low doses of radiation may be higher than is usually believed, raising questions about the potential dangers of diagnostic X-ray procedures. Research concerning this issue has suffered from methodologic limitations and from limitations inherent in the problem itself (for example, the possibility that X-rays are often performed because of symptoms of already-present disease). To learn more about the potential dangers of diagnostic X-rays, a case-control study of a large number of patients enrolled in two prepaid health plans was carried out. This approach identifies people with the diseases of interest, called cases (leukemia, non-Hodgkin's lymphoma, and multiple myeloma, representing malignancies of blood cells in which low-dose radiation has been implicated), and compares them with disease-free patients of similar age, sex, and health plan membership duration, called controls. Cases and controls were compared for their histories of diagnostic X-rays to arrive at a cumulative bone marrow dose for each subject. Results showed that slightly more than half of the 25,421 procedures performed for these patients were chest X-rays, with an average of 11.6 X-ray procedures per patient. The 207 cases with chronic lymphocytic leukemia (CLL, a slowly-progressing disorder) had been exposed to diagnostic radiation less frequently than the 238 CLL controls. For all other leukemias combined (358 cases), a nonsignificant elevation of risk (relative risk, 1.17) was seen for cases but there was no dose-response relationship after X-rays given just prior to disease diagnosis were excluded; this was also the case for non-Hodgkin's lymphoma. Thus there was little support for an association between diagnostic X-rays and the causation of either leukemia or non-Hodgkin's lymphoma. Large numbers of X-ray procedures did seem to increase the risk of multiple myeloma: those with the highest number of exposures were at a four-fold greater risk for this disease. The findings suggest that diagnostic X-rays are not a significant health hazard, but that unnecessary procedures should be avoided. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Risk factors, X-rays, Lymphomas, Leukemia, Radiography, Medical, Medical radiography, Multiple myeloma

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The emerging epidemic of melanoma and squamous cell skin cancer

Article Abstract:

Melanoma of the skin is a cancer affecting the pigment-containing cells. Recently this cancer has received great attention, and has been found to be treatable if detected at an early stage. Considerable efforts have been directed toward the screening of high-risk individuals and toward the educating of those at risk about the appearance of these lesions and their association with sunburns and with exposure to the sun. Squamous cell cancer of the skin has been less well studied than melanoma, in part because it is not generally reported to tumor registries, which are responsible for confirming cancers and recording the pertinent data of each case so that statistical analysis is possible. Despite these difficulties, it is known that the disease is related to sun exposure, and that fair-skinned individuals are at higher risk. Tumor registry data obtained within a single large HMO (health maintenance organization) in the Northwest were analyzed to outline the current demographic and statistical knowledge of squamous cell cancer of the skin. The population includes 300,000 individuals who compose the rolls of the HMO during a 27-year period (1960 to 1986). The report includes 1,876 cases of invasive squamous cell carcinoma and 577 cases of invasive melanoma. The data establish that the risk of squamous cell carcinoma increases with age, and that the rate of both skin cancers for both men and women increased during the period of study, nearly 300 percent over the 27 years. The increase may be related to a widespread change in lifestyle which permits or encourages greater exposure to ultraviolet rays of the sun, producing greater frequency of burns and blistering as a result. Because these cancers appear to be caused by, or at least strongly related to sun-exposure, simple protective measures can prevent them. Increased monitoring of the skin in high-risk patients (including those with a high rate of nonmalignant skin growths such as occur in dysplastic nevus syndrome, and those with fair skin) allows early detection and treatment.

Melanoma

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The epidemic of squamous cell carcinoma

Article Abstract:

The largest organ of the human body is the skin. The skin performs many functions and separates us from our often hostile environment. Pollutants in the environment can lead to various forms of skin cancer, including squamous cell carcinoma. Various underlying risk factors of this cancer have been described including hydrocarbons, arsenic, insecticides, X-rays and other sources of radiation. Other causative factors include burns, scars, chronic conditions and inflammation of the skin. Perhaps the most dangerous cause of all is exposure to the sun, in particular, exposure to the ultraviolet end of the spectrum. Ultraviolet radiation has been recognized as a causative agent in malignant melanoma, basal cell carcinoma (the most common form of skin cancer), cataracts, aging and various degenerative skin conditions. While the increased rate of squamous cell carcinoma may be artifactual, and there is unfortunately considerably less data to go on than for melanoma. The incidence of this disease appears to have been increasing for decades. The increase in squamous cell cancer may be linked to increased ultraviolet radiation because of changes to the ozone layer of the stratosphere, and because of changes in lifestyle that have encouraged increased exposure. To reverse the trends it is important that the stratosphere be protected, and that individuals understand the dangers of the sun, and in particular sunbathing. The use of protective clothing, hats and sun-blockers, and avoidance of exposure between 10:00 AM and 2:00 PM, are strategies that can significantly reduce the possibility of many forms of skin cancer, including squamous cell cancer.

editorial

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