Kaposi's sarcoma, a debilitating cancer most often seen in HIV-positive homosexual men, is caused by a virus called HHV-8, and, among homosexual men, is most often transmitted sexually, according to a UC San Francisco study published in the April 2 issue of the New England Journal of Medicine.
Moreover, according to the study, transmission of HHV-8 increases with the number of years of regular sexual intercourse among homosexual men, the number of past homosexual partners and a past history of several sexually transmitted diseases. The study found that HIV-positive men infected with HHV-8 have, approximately, a 50 percent chance of developing Kaposi's sarcoma within 10 years.
The investigators found that HHV-8 antibodies preceded the subsequent development of Kaposi's sarcoma, and that the markedly increased risk of developing Kaposi's sarcoma in the HIV-positive men studied was dependent on infection with HHV-8 alone, rather than on some other sexually transmitted organism. This finding provides the strongest proof to date that HHV-8 is a cause, not a result, of Kaposi's sarcoma.
The UCSF finding solves a mystery that has puzzled researchers since 1994, when they discovered unusual DNA sequences in the cells of skin lesions associated with Kaposi's sarcoma. Until now, scientists have not known whether the virus represented by these sequences, which they called human herpesvirus 8, or HHV-8, caused the disease or was an "innocent bystander" that merely traveled with another, as yet undiscovered, culprit agent.
The UCSF study is the first large-scale investigation to demonstrate a
direct association between HHV-8 and Kaposi's sarcoma, by showing that HHV-8
infection precedes the development of Kaposi's sarcoma and by meticulously
eliminating other variables that could explain the cause. It is also the first
study to examine the frequency of the virus in a randomly chosen sample of the
population and to examine modes
Contact: Jeniffer O'Brien
University of California - San Francisco