The Body Covers: The 4th International AIDS Malignancy Conference
May 16-28, 2000
Each year at this conference, there is a discussion of which cancers are more common in HIV infection. Of course, it has been obvious for years that such diseases as KS and lymphoma are related. But it has been more difficult to determine which cancers may only be moderately or slightly more common in AIDS. In the past few years, the list has become longer, and now includes not only KS, primary brain lymphoma, and non-Hodgkin's lymphoma (AIDS-NHL) but also the Hodgkin's type of lymphoma, rarer tumors in special risks groups such as a tumor of the eye in subsaharan Africa, and a smooth muscle tumor called leiomyosarcoma in children. Also, pre-malignant and malignant tumors of the anus have received more press in the last few years, even though they are epidemiologically related to another sexually-transmitted virus called papilloma virus and therefore, number of sexual partners, rather than being directly related to HIV.
Valerie Beral, in an international collaborative study reviewing multiple different epidemiologic surveys of areas throughout the world, estimated the risk of developing various cancers in HIV compared to HIV-negative subjects. She saw that lung cancer was increased in risk to about double that of a matching HIV-negative group of people. This finding was supported by estimates by Robert Biggar from the National Cancer Institute (NCI), although he felt that his data might be explained by the fact that people with HIV smoke more than the average in the United States. Whatever the explanation, a doubling of the risk of the most common cancer in the world means that it may become a significant problem in the care of people with HIV in future years, especially since many are living to an older age when the risk of lung cancer rises noticably.
Other malignancies reported to be at an increased incidence include penis, vulvar, and anal cancers. There is a 5- to 6-times risk of cancer of the penis in men with HIV, which is only seen in Africa on a regular basis. A 5-times risk increase in cancer of the vulva and a 28-times risk of anal cancer were also observed. These cancers are usually related to the same human papilloma virus (also called HPV) that causes cervical cancer. A malignancy that is less often discussed with reference to HIV is primary liver cancer, also known as hepatocellular carcinoma or hepatoma, which is related to two other infections that frequently afflict people with HIV, hepatitis B and C. Valerie Beral reported nearly 7-times the risk of primary liver cancer in people with HIV, and this increase was seen predominantly in patients in the US and Europe. Hepatocellular carcinoma is a relatively untreatable type of cancer, although it can occasionally be cured by surgical removal of the tumor from the liver or replacement of the liver by transplantation. However, this distribution of the disease may change, as the rates of hepatitis in Asia are quite high. It is clear that having HIV and hepatitis act in concert to increase the risk of liver cancer since people with both HIV and hepatitis C develop cancer much more readily than those with only one of either infection. Therefore, we will likely see a rise in the number of new cases. Fortunately, there does seem to be a lag time of many years between the development of hepatitis and HIV and the point of developing cancer in most patients.
The previously reported drop in the number of new KS cases was confirmed by a number of investigators. Estimates of the decrease range between a two-thirds and three-quarters reduction in the number of new cases per year since 1990. This, of course, pre-dates highly active antiretroviral therapy by a number of years. It is not clear exactly what accounts for this drop in incidence, but it seems to be multifactorial, including changes the composition of risk groups for HIV, changes in sexual practices, and of course, antiretroviral therapy. There seems to be some early signs of increases in KS rates in the last year or so, possibly associated with higher rates of resistance to antiretroviral drugs. No investigator found any similar fall in the likelihood of developing AIDS-related lymphoma, although some minor decreases have been seen.
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