Merkel cell carcinoma of the skin.

Merkel cell carcinoma is a rare, aggressive neuroendocrine tumor of the skin with a predisposition for local regional and distant spread. Radiotherapy after wide local excision has improved local control, but distant spread continues to be a significant problem. This is an update of our experience in the treatment of Merkel cell carcinoma at the University of Florida. Of 24 patients who were treated for Merkel cell carcinoma between 1984 and 1996, 18 patients were treated at the time of the initial diagnosis, and six were treated after local-regional recurrence. Of the 18 previously untreated patients, 13 had primary sites in the head and neck region, and five had primary sites elsewhere. Minimum follow-up was 1 year; no patient was lost to follow-up. The 5-year absolute survival, cause-specific survival, and local-regional control rates for the entire group were 27%, 31%, and 78%, respectively. Patients who were treated with radiotherapy at the time of initial presentation had 5-year absolute survival, cause-specific survival, and local-regional control rates of 38%, 44%, and 73%, respectively. Most deaths were due to distant metastasis. Site of the primary tumor (head and neck versus other) was not associated with any difference in the outcome. Of six patients who were treated at the time of local-regional recurrence, five developed distant metastasis at 3-19 months (median 8 months) from the time of treatment. One patient was alive and without evidence of disease 13 months after treatment. All patients who were treated at the time of local-regional recurrence had local-regional control after radiotherapy at 3-30 months (median 8 months). Wide local excision and radiotherapy is effective local-regional treatment for Merkel cell carcinoma of the skin, but distant metastasis remains a significant problem in this disease. The role and effectiveness of chemotherapy as part of the initial treatment remains to be defined.