People with HIV are increasingly being diagnosed with a non-AIDS-defining cancer for a second time, a phenomenon driven in part by longer life spans.

Researchers analyzed data on primary cancers among 22,600 people who were diagnosed with HIV in San Francisco between 1990 and 2010. They identified 4,550 primary cancers, including 4,150 that were an individual’s first diagnosis of cancer and 370 second primary cancers.

A primary cancer is a novel malignancy, as opposed to cancer that spread from another source.

Fourteen first primary cancers were more commonly diagnosed among people with HIV compared with the diagnosis rate among the general population—including by a factor of 127-fold for Kaposi sarcoma, 47-fold for anal cancer, 17-fold for non–Hodgkin lymphoma, 13-fold for vulvar cancer, 10-fold for Hodgkin lymphoma and 8-fold for invasive cervical cancer.

Compared with the general population, the diagnosis rate for second primary cancers was higher by a factor of 28-fold for Kaposi sarcoma, 17-fold for anal cancer, 11-fold for non–Hodgkin lymphoma, 5-fold for Hodgkin lymphoma and 4-fold for liver cancer.

The diagnosis rate in the HIV population of both first and second primary cancers that were AIDS-defining declined during the study period. Meanwhile, the diagnosis rate of second primary cancers that were non-AIDS-defining increased.

“People can reduce their risk for developing either a first or subsequent cancer by making lifestyle changes,” advises study author Nancy A. Hessol, MSPH, a professor of clinical pharmacy and medicine at the University of California, San Francisco, “such as avoid using tobacco and alcohol. Remaining adherent to [antiretroviral treatment] is also important for keeping HIV in check and maintaining the immune system.”