AIDS-related cancers in the era of highly active antiretroviral therapy

Highly active antiretroviral therapy (HAART) has shown great efficacy in re ducing human immunodeficiency virus levels, increasing immunity, and prolon ging the survival of persons with acquired immunodeficiency syndrome (AIDS) . The risk of life-threatening infections has been greatly reduced. However , the impact of HAART on the incidence of malignancy has been less clear. P ublished studies generally show that the risk of developing Kaposi's sarcom a declined by about two-thirds between 1994 and 1995 and from 1996 onward ( considered the HAART era). Even before 1994, the risk of Kaposi's sarcoma i n persons with AIDS had declined considerably and this cancer has now becom e relatively uncommon. The mechanism by which this decline in incidence was achieved appears to involve improved immunity. Data on the reduction in th e risk for non-Hodgkin's lymphoma, although the most recent data (from 1997 to 1999) show a 42% decrease in risk. Even with a one-third reduction, the risk for non-Hodgkin's lymphoma remains considerably elevated. This high r isk may be related to the fact that HAART therapy does not restore the immu ne system to normalcy. The increased lymphocyte turnover, with its accompan ying risk of genetic errors, may increase the risk of developing non-Hodgki n's lymphoma. Most reports have insufficient data to analyze the impact of HAART therapy on incidence of central nervous system lymphomas, but recent data (from 1997 to 1999) showed a significant reduction in that risk. The m echanism by which this might occur is unclear because the central nervous s ystem is an immunologic sanctuary. The relatively low incidence of other ca ncers in persons with AIDS makes it difficult to gauge the effect of HAART on their incidence, but to date, no significant trends have been reported f or specific tumor types or for the overall risk on non-AIDS-related cancers .