The role of radiation therapy and chemotherapy in the treatment of Merkel cell carcinoma

BACKGROUND: Merkel cell carcinoma is a rare and highly aggressive skin tumor. The purpose of this study was to determine the role of radiation therapy and chemotherapy in the treatment of patients with Merkel cell carcinoma. METHODS: A retrospective analysis of 27 patients treated at Rabin Medical Center in Israel is presented, focusing on the treatment details. Data for 40 patients (the authors' 27 patients and an additional 13 patients from the Israeli Cancer Registry), were analyzed for prognostic factors using univariate and multivariate analyses. RESULTS: Univariate analyses revealed regional lymph node involvement and the coexistence of a second primary tumor as unfavorable prognostic factors. On multivariate analysis, only lymph node involvement showed borderline statistical significance. Radiation therapy was highly effective when given as consolidation after surgery or chemotherapy. In 11 patients irradiated effectively, only 1 (9%) in-field recurrence occurred. Radiation therapy yielded responses in 15 of 15 measurable sites (5 complete responses and 10 partial responses). Chemotherapy produced responses in 18 of 26 patients (69%), mostly complete (41%). However, in the absence of radiation therapy, the responses were short lived. CONCLUSIONS: These data support the use of combined treatment with chemotherapy followed by radiation therapy for patients with advanced locoregional Merkel cell carcinoma. In patients with metastatic disease, chemotherapy as well as radiotherapy can provide effective palliation. Further large scale investigations are warranted to confirm this approach.