Background:  Infection with HIV-1 increases the risk of certain, but not of all, types of cancer. A common feature of these malignancies is that specific infectious agents appear to be important in their aetiology, not only in immunodeficient people but also in the general population. Although the incidence of many cancers has been reported to be increased in people with HIV infection, for only a few is the evidence sufficiently strong and consistent that it is possible to conclude that there is a definite increase in risk. Infection with HIV is causally associated with Kaposi’s sarcoma, non-Hodgkin lymphoma, conjunctival squamous cell carcinoma, and, in children, leiomyosarcoma. For each of these malignancies, other known viruses, notably human herpesviruses and papillomaviruses, are believed to be important causes. Moreover, similar associations between these viruses and cancers have been found in people who are not immunosuppressed. The greatest burden of HIV-associated malignancies is carried by countries in sub-Saharan Africa, in part because HIV infection is most common there, but also because some of the underlying causes of these cancers (such as the Kaposi’s sarcoma-associated herpesvirus) are more prevalent in the general population there than elsewhere.

Conclusions:  In resource-rich settings, the widespread use of HAART has resulted in a substantial reduction in the incidence of Kaposi’s sarcoma and non-Hodgkin lymphoma among HIV-infected people but, so far, little change in the incidence of other cancers. In resource-poor settings, where HAART is still not widely available, the incidence of HIV-associated malignancies continues to increase. For example, in Africa, where the underlying viral cause of Kaposi’s sarcoma is widespread, there has been an explosion in the incidence of the tumour with the spread of HIV. In many countries in sub-Saharan Africa, it is now the most frequently reported malignancy, more common among men in some places than all other cancers combined. In contrast, in the United States, Europe, and Australia, the incidence of Kaposi’s sarcoma among HIV-infected people has declined by at least 70% since 1997, when HAART became widely available. The risk of cancer among long-term users of HAART remains uncertain.