Background: In addition to Kaposi's sarcoma and non-Hodgkin's lymphomas, it has been postulated that human immunodeficiency virus (HIV) infection may increase the risk of other cancers. The aim of the current study was to compare incidence rates of cancer among individuals who seroconverted for HIV infection with the rates in the general population of Italy.
Methods: This study is part of an ongoing cohort investigation conducted by the HIV Italian Seroconversion Study Group. The study has enrolled 1255 individuals (906 males and 349 females) between the ages of 20 and 49 years who are at risk for HIV infection and have had a documented negative HIV test followed by a positive test. For each individual, the midpoint in time between the negative and positive tests was used to estimate the seroconversion date. The person-years at risk for cancer were then computed from the midpoint date to the last follow-up date or to death, and the number of cases of cancer observed in the cohort was compared with the expected number, based on rates among the general population of the same age and gender. Standardized incidence ratios (SIR) and 95% confidence intervals (CI) were computed.
Results: A total of 58 cases of cancer were observed in the cohort. In comparison with rates in the general population, Kaposi's sarcoma was 1051 times more frequent, and non-Hodgkin's lymphomas were 157 times more frequent. Hodgkin's disease was observed in 3 men (i.e., 38 times more often in the cohort of HIV seroconverters [95% CI, 8-111]), in particular among homosexual men (SIR = 103). One woman developed stomach carcinoma.
Conclusions: The findings of the current incidence study are in agreement with previous studies showing excesses of Kaposi's sarcoma and non-Hodgkin's lymphomas in HIV-positive individuals. In addition, the findings suggest an association of HIV infection with Hodgkin's disease. Whether Hodgkin's disease in HIV-infected individuals should be considered an AIDS-defining illness is a question that is worthy of attention.