Merkel cell carcinoma: long-term follow-up of a single institution series and clinical outcomes by immunological status.

Merkel cell carcinoma (MCC) usually arises in sun-exposed areas of older patients and might be more aggressive in the immunocompromised. We performed a retrospective chart review of 40 consecutive MCC patients treated at our institution between the years 2006-2017. Clinical and epidemiologic data were utilized and therapy and survival were analyzed. Compared to Surveillance, Epidemiology, and End Results (SEER) data, our population was entirely Caucasian (100% versus 95%; P=0.11) and male predominant (75% versus 63%; P=0.11). The median age was 76. The patients more often had Tumor-Node-Metastasis (TNM) stage I disease (50% versus 39%; P=0.00003) and a primary tumor size <2cm (57.5% versus 34%; P<0.01). They received more frequently lymph node dissection (70% versus 63%, P=0.002) compared with the SEER findings. We identified a subset of immunocompromised patients (n=10) who presented with more stage III disease (40% versus 33%; P=0.021). Time to death averaged 290.1 days in this subset versus 618.2 days (P<0.001) in immunocompetent patients and their likelihood of death was 5 times higher. As clinical outcomes in MCC patients vary by immunological status, a multidisciplinary tumor-board approach may better optimize individual patient management.