Adjuvant radiation therapy is associated with improved survival in Merkel cell carcinoma of the skin

Purpose Merkel cell carcinoma (MCC) is a rare cutaneous malignancy. Because of the absence of randomized studies, the real benefit of adjuvant radiation therapy in MCC is unclear. The aim of this study was to better define the role of adjuvant radiation therapy in the management of MCC. Methods The Surveillance, Epidemiology, and End Results (SEER) survey from the National Cancer Institute was queried from 1973 through 2002. Retrospective analysis was performed. The end point of the study was overall survival. Results There were 1,665 cases of MCC in the SEER registry. Presentation by stage were 55% stage I, 31% stage II, and 6% stage III. Eight percent of the cases could not be staged because of incomplete data. Surgical intervention was a component of therapy in 89% of the cases (n = 1,487). The median survival for the entire cohort was 49 months, and median follow-up was 40 months. Adjuvant radiation was a component of therapy in 40% of the surgical cases. The median survival for those patients receiving adjuvant radiation therapy was 63 months compared with 45 months for those treated without adjuvant radiation. The use of radiation was associated with an improved survival for patients with all sizes of tumors, but the improvement with radiation use was particularly prominent when analyzing those patients with primary lesions larger than 2 cm. Conclusion The use of adjuvant radiation therapy is associated with improved survival in patients with MCC. Prospective evaluation of adjuvant radiation therapy in this setting is warranted.