Men with HIV, nonmelanoma skin cancer at greater risk for Kaposi’s sarcoma

Men with HIV and nonmelanoma skin cancer faced an elevated risk for Kaposi’s sarcoma, as did men with HIV who lived in locations with high levels of ambient ultraviolet radiation at the time of diagnosis, study data showed.

“In the absence of severe immunosuppression, Kaposi’s sarcoma has a distinctive geographic distribution, with high incidence in Equatorial Africa and among older people of Mediterranean descent,” Elizabeth K. Cahoon, PhD, of the radiation epidemiology branch of the NCI, and colleagues wrote. “Evidence has confirmed human herpes virus 8 (HHV8) to be a necessary but insufficient cause of Kaposi’s sarcoma, and that immunosuppression contributes through loss of control of HHV8 infection.”

Exposure to solar ultraviolet radiation is the primary environmental risk factor for most skin cancers. However, the relationship between ultraviolet radiation and risk for Kaposi’s sarcoma has been unknown.

Cahoon and colleagues performed a nationwide study of white and black male veterans who were diagnosed with HIV between 1986 and 1996 (n = 17,597). The researchers estimated hazard ratios and 95% confidence intervals to examine any association between ambient ultraviolet radiation, history of nonmelanoma skin cancer and incidence of first primary Kaposi’s sarcoma.

The researchers identified 422 newly diagnosed cases among the total cohort. Patients with prior nonmelanoma skin cancer had a significantly increased risk for developing Kaposi’s sarcoma (HR = 8.64; 95% CI, 6.23-11.96).

Among the total cohort, risk was significantly higher for ambient ultraviolet quartile 4 compared to quartile 1 (HR = 1.49; 95% CI, 1.02-2.16), as well as among white patients (HR = 1.75; 95% CI, 1.02-2.16), but not among black patients (HR = 1.23; 95% CI, 0.71-2.15).

A test for interaction by race revealed no statistical difference in the dose–response trends between white patients and black patients.

“This is the first study to evaluate the role of ambient solar ultraviolet radiation exposure and nomelanoma skin cancer in relation to Kaposi’s sarcoma,” the researchers wrote. “To confirm and clarify potential mechanisms, effects of ultraviolet radiation on HHV8 reactivation should be studied in experimental settings. If further researcher supports a causal relationship, understanding the timing of ultraviolet radiation exposure in relation to Kaposi’s sarcoma could inform prevention strategies.” – by Andy Polhamus