Researchers characterized patterns of nonkeratinocyte skin cancers in immunosuppressed solid organ transplant recipients (SOTRs) and found factors associated with these cancers that may help to identify risk. Their study results were published in the journal JAMA Dermatology.
“Skin is a common site for cancers in SOTRs, but risk factors for skin cancer have not been systematically evaluated for this immunosuppressed group,” the researchers explained.
This population-based cohort study, the Transplant Cancer Match Study, involved data from the Scientific Registry of Transplant Recipients linked to 32 cancer registries within the US. Included patients had undergone transplantation between January 1, 1987, and December 31, 2017. The researchers evaluated risks among SOTRs relative to the general population, in addition to factors contributing to risk.
In this analysis, 444,497 SOTRs were identified, with a median age of 50 years at transplantation. Across the cohort, 2380 SOTRs had nonkeratinocyte skin cancers diagnosed. This represented an approximately 2-fold higher risk among SOTRs than seen in the general population (standardized incidence ratio [SIR], 2.18; 95% CI, 2.09-2.27; P <.001). The researchers considered this to reflect an excess absolute risk of 50.3 additional skin cancers per 100,000 person-years.
Melanoma was the most common type of skin cancer in this population of SOTRs, representing 61.8% of the nonkeratinocyte skin cancers diagnosed in this population. Other types found were Merkel cell carcinoma in 14.0%, Kaposi sarcoma in 7.8%, sebaceous carcinoma in 7.1%, and lymphomas in 4.5%.
Compared with the general population, SOTRs had elevated risks for Kaposi sarcoma (SIR, 20.5; 95% CI, 17.7-23.7), Merkel cell carcinoma (SIR, 16.2; 95% CI, 14.5-18.1), and sebaceous carcinoma (SIR, 15.2; 95% CI, 13.0-17.7). Melanoma risk was slightly elevated (SIR, 1.52; 95% CI, 1.44-1.60), especially with amelanotic and nodular subtypes. Risk of lymphomas also was elevated in SOTRs (SIR, 2.25; 95% CI, 1.84-2.71), which varied across lymphoma subtypes.
Many risk factors appeared associated with the increased risks for these skin cancers among SOTRs, although there was variation by cancer type. Some factors had independent associations with elevated risks across several types of skin cancer, including older age at transplant, prolonged time since transplantation, male sex, and factors linked to risks with ultraviolet radiation (UVR) exposure. However, use of mammalian target of rapamycin (mTOR) inhibitor therapy was linked to a lower risk of melanoma (incidence rate ratio [IRR], 0.75; 95% CI, 0.57-0.98) but an increased risk of Merkel cell carcinoma (IRR, 1.87; 95% CI, 1.24-2.81).
“Risk of many of these cancers is strongly increased among SOTRs, and viruses, UVR exposure, and immunosuppression likely play important roles in their etiology,” the researchers concluded. These results support changes to screening guidelines for SOTRs, including wider use of mTOR inhibitors in high-risk patients.
Sargen MR, Cahoon EK, Yu KJ, et al. Spectrum of nonkeratinocyte skin cancer risk among solid organ transplant recipients in the US. JAMA Dermatol. Published online March 9, 2022. doi:10.1001/jamadermatol.2022.0036