Radiotherapy alone for Merkel cell carcinoma: a comparative and retrospective study of 25 patients.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare skin cancer. Cumulative data from retrospective series support the notion that benefits are obtained by both wide excision and adjuvant radiation therapy. However, surgery may be difficult to perform with tumors located in the head and neck region and/or in elderly patients with comorbidities incompatible with general anesthesia. OBJECTIVE: We assessed the benefit of treating MCC exclusively with radiation when conventional treatment (surgery followed by radiotherapy) is not possible. METHODS: A total of 25 patients with primary MCC were treated at our institution exclusively with radiotherapy. Because there is no consensus about this specific approach, we compared the recurrence rate of the 25 patients receiving radiotherapy alone with that of 25 patients who received conventional treatment at our institution. RESULTS: The median follow-up periods were 3 years (range: 5 months-11 years) for the group receiving only radiotherapy (group 1) and 9 years (range: 12 months-16 years) for the conventional therapy group (group 2). No local relapses were observed, but two locoregional relapses were observed in group 1, and 4 in group 2. No statistical differences were found in overall and disease-free survival between the two groups of patients. LIMITATIONS: The limitation of this study is its retrospective nature. CONCLUSIONS: This study confirms the results of our previous research demonstrating that it is possible to treat inoperable MCC exclusively with radiotherapy to obtain an outcome similar to that which is achievable with conventional treatment.