Background: Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine malignancy with an ill-defined natural history following locoregional recurrence. Methods: This is a retrospective review of patients with MCC diagnosed at the Mayo Clinic from 1981 to 2008. For each outcome (subsequent locoregional recurrence, distant recurrence, and death) the survival-free of the outcome was estimated using the Kaplan-Meier method. Associations of patient and clinical characteristics with the outcomes were assessed by fitting Cox proportional hazards regression models. Results: Among the 240 patients diagnosed with MCC, 70 (29%) patients were identified who developed locoregional recurrence as the first site of recurrence. The median time from diagnosis to locoregional recurrence was 6 months. The pattern of first locoregional failure in this group includes 25 (10.4%) local, 18 (7.5%) in-transit, and 27 (11.3%) nodal recurrences. Recurrences were most commonly treated by surgery and radiation. At 3 years after the initial recurrence, locoregional recurrence-free survival was 75% and the distant recurrence-free survival was 56%. Locoregional recurrence is a poor prognostic sign associated with a 3-year overall survival of 39%. Nodal status at time of original surgery and time to first recurrence were important predictors of distant recurrence (P < 0.006) and overall survival following locoregional recurrence (P < 0.001). Conclusions: Locoregional recurrence is a substantial problem in patients with MCC and is a poor prognostic sign. In those patients who experience a locoregional recurrence, aggressive efforts to regain locoregional control appear warranted and may result in long-term survival.
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