Background: Merkel cell carcinoma (MCC) is a rare cutaneous malignancy. Few single-institution series have been reported.
Methods: Review of MCC patients treated at our institution between 1980 and 2010. Patient, tumor, and treatment variables were analyzed to determine MCC-specific outcomes.
Results: We identified 161 patients with MCC. There was a 2.5-fold increase in cases over the last decade. Median length of follow-up was 36 months. Stage at diagnosis was I in 35 %, II in 21 %, IIIa in 12 %, IIIb in 23 %, and IV in 9 %. The 5-year MCC-specific survival rates were 87, 63, 42, and 0 % for stages I, II, III, and IV, respectively. Death from the disease occurred in 10 % of patients with T1 and in 50 % with larger lesions. One-third of patients presented with nodal disease. Sentinel lymph node biopsy (SLNB) identified micrometastases in 9 out of 27 (33 %) early-stage patients. Recurrence developed in 56 % of SLNB-positive and 39 % of SLNB-negative patients. Half of patients recurred after a median time of 9 months. Proportions of first recurrence location were distant (52 %), nodal (27 %), and local (21 %). Adjuvant treatments did not improve recurrence or survival rates. One-third of patients died of the disease.
Conclusions: SLNB identifies micrometastasis in one-third of early-stage patients. Negative SLNB may predict for improved but not necessarily favorable outcome. Initial tumor size and clinical nodal disease predict for poor outcome. High recurrence rates warrant the development of more effective adjuvant therapies, and better markers of recurrence and treatment response for MCC are needed.