Merkel Cell Carcinoma of the Skin: A Retrospective Study of 24 Cases by the Hellenic Cooperative Oncology Group

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Abstract
The purpose of this retrospective study was to present the epidemiological and clinical characteristics of 24 patients with Merkel cell carcinoma of the skin (MCC) and their response to various therapeutic modalities. The tumor registry of the Hellenic Cooperative Oncology Group was used to identify patients with MCC diagnosed between 1986 and 2006. The most frequent primary sites were the extremities (50%), followed by the head (33%) and the trunk (17%). Median time of follow-up was 24 months. Sixteen patients were initially diagnosed with stage I, 5 patients with stage II, and 3 patients with stage III (metastatic) disease. Six patients with stage I disease received adjuvant chemotherapy (CT) and/or radiotherapy (RT). All patients with stage I disease treated only with surgery relapsed, whereas 33% of the patients treated with adjuvant therapy recurred. All patients with stage II disease received adjuvant treatment. Among them, 2 patients relapsed. Disease-free survival (DFS) and overall survival (OS) did not differ significantly between patients with stage I and II disease (stage I: 4-year DFS 27%, 4-year OS 56%; stage II: 4-year DFS 60%, 4-year OS 80%). Patients treated with adjuvant therapy had significantly better DFS than those treated only with surgery (p = 0.012), but OS did not differ significantly (adjuvant group: 4-year DFS 59%, 4-year OS 74%; surgery group: 4-year DFS 10%, 4-year OS 50%). Eleven patients with locally advanced or metastatic disease received CT. The response rate was 73% (complete remission 18%), median progression-free survival was 10 months and median OS was 14 months. Complete remission was achieved in 2 other cases, with the addition of RT after CT. MCC is an aggressive neoplasm with significant chemosensitivity and radiosensitivity, but poor outcome. The role of adjuvant treatment should be further investigated.