Merkel cell carcinoma: prognosis and treatment of patients from a single institution.

PURPOSE: Merkel cell carcinoma (MCC) is an uncommon cutaneous malignancy. Most reports consist of single-institution experiences of fewer than 30 patients. The natural history of MCC is poorly defined.

PATIENTS AND METHODS: A review was performed of Memorial Sloan-Kettering Cancer Center's MCC database, identifying 251 patients who had been treated between 1970 and 2002. Patient, tumor, and treatment-related factors were analyzed for their association with recurrence and survival.

RESULTS: The average follow-up for all patients was 40 months and 46 months for patients alive at last follow-up. The 5-year disease-specific survival rate was 64%. Disease stage was the only independent predictor of survival (stage I, 81%; stage II, 67%; stage III, 52%; stage IV, 11%; P = .001). Pathologic staging of the draining nodal basin was performed in 71 (40%) of 177 patients who presented with clinically negative nodes, and 16 of these patients (23%) were found to have node-positive disease. Pathologic nodal staging was associated with improved stage-specific survival probabilities (clinical node-negative, 75% v pathologic node-negative disease, 97%; P = .009) and decreased nodal recurrence (44% v 11%, P < .001). The median time to recurrence was 9 months, and 102 patients (43%) recurred. Local recurrence developed in 8% of patients after margin-negative excision.

CONCLUSION: These data demonstrate that the natural history of MCC is variable and dependent on the stage of disease at presentation. Pathologic nodal staging identifies a group of patients with excellent long-term survival. After margin-negative excision and pathologic nodal staging, local and nodal recurrence rates are low.