Cancers are a range of diseases caused by uncontrolled cell division.

A number of cancers occur more frequently among people with HIV than in the general population. Some of these cancers are AIDS-defining illnesses, such as Kaposi's sarcoma (KS), non-Hodgkin's lymphoma (NHL), and cervical cancer.

Other cancers are not identified as AIDS-defining illnesses, despite a higher incidence among HIV-infected people. These non-AIDS-defining cancers include Hodgkin's disease; anal cancer; squamous cell carcinoma of the eye (conjunctival), skin, lip and anogenital region; testicular cancer; lung cancer; multiple myeloma (a type of leukaemia); and leiomyosarcoma (a type of connective tissue cancer).

These cancers are not regarded as AIDS-defining because the increased incidence has not been definitively linked to immune deficiency. Other factors such as high smoking rates or sexual activity may account for the high incidence.