Incidence of nonmelanoma skin cancers two-fold higher for HIV-positive patients
HIV-positive patients have a higher incidence of nonmelanoma skin cancers. Specifically, basal cell and squamous cell carcinomas occur more than twice as often among HIV-positive persons compared with those who are HIV-negative.
Nonmelanoma skin cancers are the most common cancers in the United States, with more than 3.5 million new cases diagnosed each year. Although most nonmelanoma skin cancers are easily cured, many become locally invasive and destructive.
The study cohort of 6,560 HIV-positive and almost 37,000 HIV-negative subjects was drawn from members of Kaiser Permanente Northern California from 1996 to 2008. Overall, HIV-positive participants had a 2.1-fold higher risk for basal cell carcinomas and a 2.6-fold higher risk for squamous cell carcinomas, compared to HIV-negative participants. In addition, squamous cell carcinomas were associated with lower CD4 counts, a measure of immunodeficiency. Prior antiretroviral therapy was not found to be associated with the incidence of either squamous cell carcinomas or basal cell carcinomas.
“These findings represent unique data on nonmelanoma skin cancers in HIV patients. Most cancer registries, on which previous studies relied, do not record these types of cancers,” said lead author Michael J. Silverberg, PhD, MPH, of the Kaiser Permanente Division of Research. This study was published in the Journal of the National Cancer Institute (2013; doi:10.1093/jnci/djs529).
“In the general population, we see one case of squamous cell carcinoma for every four cases of basal cell carcinoma,” said senior author Maryam M. Asgari, MD, MPH, also of Kaiser Permanente. “It was notable in this study that for HIV-positive subjects with high CD4 counts, this ratio was similar to HIV-negative subjects. But for HIV-positive subjects with low CD4 counts, there was one case of squamous cell carcinoma for every two cases of basal cell carcinoma.”
The increased incidence rate of nonmelanoma skin cancers in HIV-positive participants is consistent with the growing evidence about this population's increased risk for a broad range of cancers, according to the study authors. They cited a large meta-analysis in which both HIV/AIDS and organ-transplant populations exhibited increased incidence for many types of cancer. The increased cancer risk is likely due to immunodeficiency, the main risk factor these populations have in common. This conclusion was reinforced by a recent large, population-based study of US transplant recipients.
“The clinical implications for these findings include increased vigilance in skin cancer screening for HIV-positive individuals, especially for squamous cell carcinomas and particularly for those who are not on antiretroviral therapy or who were diagnosed late and have more advanced HIV/AIDS,” said Asgari. HIV-positive patients should be advised to reduce behaviors that may further increase nonmelanoma skin cancer incidence, such as excessive sun exposure. In addition, given the observed association of immunodeficiency and squamous cell carcinomas, earlier initiation of antiretroviral therapy may also help reduce the burden of this cancer.