By 2004, the number of cases increased 30% (4). In the HIV positive population the rate of anal cancer increased from 19 to 78.2 per 100,000 person-years (4). 80% of anal cancers involve the anal canal with the majority being squamous cell carcinomas (5). One major factor implicated in the increase in anal cancer from the 1990’s to now is the HIV virus. It is known that the incidence of anal cancer is 40 to 80 times higher in the HIV+ population. HIV+ patients tend to get anal cancer at a younger age, are more frequently men, and more Inhibitors,research,lifescience,medical frequently homosexual men who practice RAI (6). Cancer has been

associated with HIV since the first reports of AIDS in the 1980s. Three different cancers are AIDS defining: Kaposi’s sarcoma, Non-Hodgkin’s Lymphoma (B cell), and invasive cervical cancer. Anal cancer is part of a group of non-AIDS defining cancers which include Hodgkin’s lymphoma, lung adenocarcinoma, hepatocellular carcinoma, oropharyngeal carcinoma, kidney carcinoma, Inhibitors,research,lifescience,medical melanoma, and conjunctival carcinoma (primarily sub-Saharan Africa) (4). These non AIDS defining cancers have a two to three fold higher incidence in the HIV+ population (7). There are other factors implicated in the etiology of anal cancer in addition to HIV. Anal cancer, similar to cervical cancer, is known to be associated with the HPV virus, sexual behavior, and tobacco use. HPV-16 is the most prevalent subtype

associated Inhibitors,research,lifescience,medical with anal cancer and precancerous lesions followed by HPV-33 and HPV-39 (8). HPV is known to play a definitive role in the development of anal and cervical squamous cell cancer. HIV+ Inhibitors,research,lifescience,medical patients

are more likely to be co-infected with HPV, approximately 2 to 6 fold higher probably secondary to similar risk factors Inhibitors,research,lifescience,medical such as sexual behavior. In the HIV+ population, men have an increased learn more relative risk of developing anal cancer compared to women (37.9 versus 6.8) (9). That risk increases depending on sexual practices. Men who has sex with men (MSM) is associated with a higher incidence of anal cancer. HIV+ MSM have doubled the rate of anal cancer as compared to HIV- MSM (70-100 per 100,000 versus 35 per 100,000) (10). HPV infection persists in HIV+ patients compared to immunocompetent patients. HIV+ patients are seven times more likely to have persistent HPV infection. There is a suggestion that immunosuppression in HIV+ patients prevents clearance of HPV and subsequent higher risk of developing anal cancer. second The discovery and subsequent use of antiretroviral drugs (HAART) in the late 1990’s has led to a significant decrease in AIDS defining cancers. In the U.S, recommendations set forth by the United States Department of Health and Human Services for initiating HAART treatment include: all HIV positive patients who present with AIDS defining illness, and HIV positive patients with CD4<200 (cluster of differentiation 4) (11).