Merkel Cell Carcinoma: 27-Year Experience at the Peter MacCallum Cancer Centre

Purpose: To retrospectively evaluate the treatment outcome of patients with Merkel cell carcinoma after local and/or regional treatment. Methods and Materials: Patients presenting to our center between January 1980 and July 2006 with Merkel cell carcinoma and without distant metastases were reviewed. The primary endpoint was locoregional control. Secondary endpoints were distant recurrence, survival and treatment toxicity. Results: A total of 176 patients were identified. The median age was 79 years. The median follow-up was 2.2 years for all patients and 3.9 years for those alive at the last follow-up visit. The most common primary site was the head and neck (56%), and 62 patients(35%) had regional disease at presentation. The initial surgery to the primary tumor involved (wide) local excision in 140 patients and biopsy only in 28 patients (8 patients had no identifiable primary tumor); 33 patients underwent nodal surgery. Of the 176 patients, 165 (94%) underwent radiotherapy (RT) and 29 of them also underwent concurrent chemotherapy. The median radiation dose was 50 Gy (range, 18-60). Locoregional recurrence developed in 33 patients(19%), with a median interval to recurrence of 8 months. Distant metastases developed in 43 patients(24%). Age, primary tumor size, and RT (no RT vs. <45 Gy vs. ≥45 Gy) were predictive of locoregional control on univariate analysis. However, only RT remained significant on multivariate analysis. The estimated 5-year actuarial rate for locoregional control, progression-free survival, and overall survival was 76%, 60%, and 45%, respectively. Conclusion: The locoregional control rate for Merkel cell carcinoma in our study was comparable to those from other series using combined modality treatment with RT an integral part of treatment.