Viruses, ultraviolet sunlight increase skin cancer risk in posttransplant patients

Among individuals who have undergone solid organ transplantation, viral infections and exposure to ultraviolet sunlight were associated with the highest risks for skin cancers, according to a study.

“Nonkeratinocyte skin cancers are an important cause of morbidity and mortality for immunosuppressed solid organ transplant recipients (SOTRs), but the spectrum of disease and risk factor characteristics are unknown,” Michael R. Sargen, MD, of the division of cancer epidemiology and genetics at the NIH National Cancer Institute, and colleagues wrote.

In the population-based cohort study, the researchers characterized the spectrum of disease and risk factors for common and rare nonkeratinocyte skin malignancies in a cohort of 444,497 solid organ transplant recipients in the United States.

Eligible participants had undergone procedures between Jan. 1, 1987, and Dec. 31, 2017. Risk was assessed using standardized incidence ratios (SIRs) compared with the general population.

Results showed that 2,380 nonkeratinocyte skin cancers from the transplant cohort underwent analysis. Patients had a median age of 50 years (range, 0-96) at transplant. The cohort was 61.7% men and 61.2% non-Hispanic white.

The most common malignancy was melanoma at 61.8%, followed by Merkel cell carcinoma at 14%, Kaposi sarcoma at 7.8%, sebaceous carcinoma at 7.1% and cutaneous lymphomas at 4.5%.

The highest risks were reported for cancers associated with viruses, according to findings. The highest virus-related malignancy risk was for Kaposi sarcoma (SIR = 20.5; 95% CI, 17.7-23.7), followed by Merkel cell carcinoma (SIR = 16.2; 95% CI, 14.5-18.1) and extranodal natural killer/T-cell lymphoma (SIR = 44.3; 95% CI, 5.37-160).

Sebaceous carcinoma risk was significantly elevated in the transplant setting (SIR = 15.2; 95% CI, 13-17.7), as was risk for anaplastic large cell lymphoma (SIR = 6.82; 95% CI, 4.53-9.85) and diffuse large B-cell lymphoma (SIR = 5.17; 95% CI, 3.28-7.76).

Men were at elevated risk for multiple skin cancer types. Older age at transplant was another risk factor for multiple cancers, as were factors associated with UV radiation exposure such as non-Hispanic white race and ethnicity, living in a place with elevated UV radiation exposure and diagnosis of keratinocyte carcinoma following transplantation. As time passed following transplantation, cancer risk also increased.

The main factor that reduced melanoma incidence was treatment with mammalian target of rapamycin inhibitors (incidence rate ratio = 0.75; 95% CI, 0.57-0.98), according to the results.

Of the malignancies that underwent analysis, 39.4% were head and neck disease.

“The findings of this cohort study suggest that viruses, UV radiation exposure and immunosuppression are associated with the development of skin cancer in SOTRs,” the researchers concluded. “Certain high-risk subgroups may benefit from increased skin surveillance, and treatment with mammalian target of rapamycin inhibitors could be effective for melanoma chemoprevention in the transplant population.”