IAS 2011: People with HIV Have Double Risk for Non-Melanoma Skin Cancers

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Several studies conducted in the era of effective antiretroviral therapy (ART) have shown that people with HIV have higher rates of non-AIDS-defining cancers, especially those caused by infectious pathogens such as human papillomavirus or hepatitis B or C.

It is unclear, however, whether non-melanoma skin cancers such as basal cell carcinoma and squamous cell carcinoma are also more common, since they are often not recorded in cancer registries.

As described in a poster presented at the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2011) last month in Rome, Michael Silverberg from Kaiser Permanente Northern California and colleagues aimed to determine rates of non-melanoma skin cancers among HIV positive members of this large integrated healthcare system.

The researchers identified 6567 HIV positive participants and 36,887 HIV negative participants matched for age, sex, and race (all were Caucasian). Most (89%) were men, 72% were men who have sex with men, and the average age was about 42 years. The HIV positive group was more likely to smoke but less likely to be overweight.

Silverberg's team collected information from pathology reports on first biopsy-proven basal cell or squamous cell carcinomas. Participants were followed from first enrollment after 1996 (the year combination ART became widely available) until skin cancer diagnosis, loss to follow-up, or December 2008.

Results

The investigators suggested that "The two-fold higher non-melanoma skin cancer risk in HIV patients may partly result from more screening or increased sun exposure," although it is unclear why the latter would be true.

"Squamous cell carcinoma risk may also be affected by alterations in the immune system," they added. This is in accordance with findings from other studies showing that past or present immune suppression increases cancer risk, though skin cancers are not known to have an infectious cause.

Investigator affiliations: Kaiser Permanente Northern California, Division of Research, Oakland, CA; National Cancer Institute, Division of Cancer Epidemiology and Genetics, Rockville, MD.

8/2/11

Reference

M Silverberg, W Leyden, M Warton, et al. HIV infection and non-melanoma skin cancer risk. 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2011). Rome, July 17-20, 2011. Abstract TUPE235.