HIV-infected individuals who have experienced a nonmelanoma skin cancer may be at significantly greater risk of subsequent new squamous cell carcinoma if they have a lower CD4 cell count, a new study suggests.
In a study published online July 12 in JAMA Dermatology, researchers reported the results of a retrospective cohort study using medical record data from 455 HIV-infected and 1,952 HIV-uninfected patients who had previously been diagnosed with at least one nonmelanoma skin cancer.
Patients with CD4 cell counts below 200 cells/mcL had a 44% greater risk of a subsequent nonmelanoma skin cancer, compared with uninfected individuals (95% confidence interval, 1.10-1.88), while those with a viral load greater than 10,000 copies/mL had a 31% greater risk (95% CI, 1.00-1.72), after adjusting for age, sex, smoking status, and obesity.
The increase in nonmelanoma skin cancer risk was largely accounted for by an increased risk of squamous cell carcinoma (SCC). Among patients with lower CD4 cell counts and those with higher viral loads, the risk of SCC was more than twofold greater than among uninfected individuals. In contrast, while there was a trend toward a higher risk of basal cell carcinoma in those two groups, it did not reach significance (JAMA Dermatol. 2017 Jul 12. doi: 10.1001/jamadermatol.2017.1716).
Overall, HIV-infected individuals had a significant 15% increase in the risk of subsequent nonmelanoma skin cancer over an average follow-up period of 5 years, compared with uninfected individuals.
“This study addresses key questions regarding subsequent NMSC [nonmelanoma skin cancer] risk among a high-risk subgroup of HIV-infected population who, by virtue of having had a pathologically validated skin cancer, are at increased risk of subsequent NMSCs,” wrote Maryam M. Asgari, MD, of Massachusetts General Hospital, Boston, and her coauthors. “Specifically, it was previously not known precisely which NMSC subtype is increased in high-risk persons with HIV and whether biomarkers of HIV infections, such as degree of immune dysfunction, are associated with subsequent skin cancer risk.”
While the study wasn’t able to control for known skin cancer risk factors such as skin type, the patients were all non-Hispanic white, which the authors said selected for individuals with fair skin and some sun-exposure history.
The findings could have implications for skin cancer screening among individuals with HIV infection, with the authors suggesting more targeted monitoring for SCC among individuals with low CD4 counts or high viral loads.
“Our findings support immune dysfunction as a risk factor for SCCs and dovetail with SCC risk data from iatrogenic immunodeficiency states, such as organ transplantation and autoimmune diseases.”
The study was partly supported by Kaiser Permanente Northern California, and one author was supported by a grant from the National Cancer Institute. Two authors had previously served as investigators on studies funded by the pharmaceutical industry, one author declared research funding from the pharmaceutical industry, and one declared shares in two medical companies.