C. Contreras1, T. N. Canavan2, E. Malone1, J. Richman1, R. Pearlman1, C. A. Elmets3, C. Huang3, C. Contreras1 1University Of Alabama at Birmingham,Surgical Oncology,Birmingham, Alabama, USA 2New York University School Of Medicine,The Ronald O. Perelman Department of Dermatology,New York, NY, USA 3University Of Alabama at Birmingham,Dermatology,Birmingham, Alabama, USA
Introduction: Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine carcinoma that disproportionately afflicts elderly Caucasian and immunosuppressed patients. Immunosuppression correlates with worse MCC outcomes. This study compared MCC outcomes between immunocompetent patients and those with immunosuppression from various etiologies, including solid organ transplant recipients (SOTRs), those with hematologic malignancies, and therapeutic immunosuppression for other causes.
Methods: We conducted a single institution retrospective review examining the MCC disease course for all patients at our institution from 2000 to 2017. Treatments were reviewed for all patients. Stage at diagnosis was compared between immunosuppressed and immunocompetent patients. Kaplan Meier curves were generated, and hazard ratios estimated for disease-free survival and overall survival by immunosuppression status.
Results: Our cohort included 78 immunocompetent patients and 22 immunosuppressed (4 SOTR, 11 hematologic, and 7 other). There was no statistically significant difference between the presenting stages of our immunosuppressed patients (suppressed vs. competent: IA: 23% vs. 24%; IB: 23% vs. 19%; II: 9% vs. 8%; IIIA: 5% vs. 14% ; IIIB: 23% vs. 15%; IV: 18% vs. 18%; p=0.80). Of patients who had a sentinel lymph node biopsy at the time of initial staging, 30% of immunosuppressed patients had positive nodes compared to 46% of immunocompetent patients (p=0.49). Overall, 35% of the cohort was treated with resection alone, 44% were treated with the combination of surgery and radiation therapy, and 3% were treated with a combination of radiation and/or chemotherapy. All immunosuppression etiologies were associated with decreased overall and disease-free survival rates compared to immunocompetent patients in aggregate, and by type of immunosuppression: Overall: SOTR: HR=1.6 (95% CI: 0.5-5.2), Heme Malignancy: HR=2.5 (95% CI: 1.1-5.7), Other: HR=2.3 (95% CI: 1.0-5.4); Disease-free: SOTR: HR=1.2 (95% CI: 0.4-3.9), Heme Malignancy: HR=2.0 (95% CI: 0.9-4.3), Other: HR=1.2 (95% CI: 1.2-5.8). In multivariate models controlling for age, gender and stage at presentation, immunosuppression was predictive of decreased survival (Overall: HR=3.2 (95% CI: 1.6-6.1); Disease-free: HR=1.9 (95% CI: 1.1-3.5)). Immunosuppressed patients had a median disease free-survival of 8 months compared to 17 months in immunocompetent patients, p=0.03.
Conclusion: Immunosuppressed groups had worse MCC-specific outcomes relative to immunocompetent patients overall and by reason for immunosuppression. Despite heterogeneity solid organ transplant, hematologic malignancy, and iatrogenic etiology all imparted a similar risk for decreased disease free and overall survival. The modest cohort size in this single center retrospective review is inherent to this rare malignancy; further study involving multiple institutions is important to confirm these findings.