Introduction — Few studies have examined outcomes in immunosuppressed patients who develop melanoma. The purpose of this study is to compare survival in immunosuppressed patients who developed melanoma with that in patients with melanoma who are not immunosuppressed.
Methods — Immunosuppressed patients were defined as having solid organ transplant, lymphoma, leukemia, or human immunodeficiency virus prior to diagnosis of melanoma. Patients with cutaneous melanoma with and without immunosuppression were identified retrospectively from the Ontario Cancer Registry (2007-2015) and linked with administrative databases to identify demographics, treatment, and outcomes. Immunosuppressed patients were matched with non-immunosuppressed patients based on age at diagnosis, sex, birth year, stage at diagnosis, and propensity score. The primary outcome was overall survival. Multivariable Cox proportional hazard regression was used to identify factors associated with survival.
Results — Baseline characteristics were well balanced in 218 immunosuppressed patients matched to 436 controls. Of the patients, 186 (28.4%) were female, and median age at melanoma diagnosis was 69 (interquartile range, IQR 59-78) years. Three-year overall survival (OS) was 65% for immunosuppressed patients and 79% for non-immunosuppressed patients. Melanoma was the leading cause of death for both groups. On multivariable analysis, immunosuppression was associated with increased mortality [hazard ratio (HR) 1.70, 95% confidence interval (CI) 1.30-2.23]. Adequate treatment (HR 0.36, 95% CI 0.22-0.58) and dermatologist visits either before (HR 0.52, 95% CI 0.36-0.73) or after (HR 0.61, 95% CI 0.41-0.90) melanoma diagnosis were associated with improved OS.
Conclusions — Immunosuppressed patients who develop melanoma have worse outcomes when matched to non-immunosuppressed patients. This decrease in survival appears related to the underlying condition rather than diagnosis of melanoma.