Management of cutaneous Merkel cell carcinoma

To report the outcomes of patients with previously untreated cutaneous Merkel cell carcinoma (MCC) managed with curative intent.

Between December 1984 and August 2015, 59 patients with previously untreated cutaneous MCC were managed with curative intent with surgery and adjuvant radiotherapy (54 patients) or radiotherapy alone (5 patients) at the University of Florida. Primary sites included head and neck (45 patients), extremities (11 patients) and trunk (3 patients). Adjuvant chemotherapy was employed in 14 patients. Patients were staged according to the AJCC staging system: stage I, 25 patients; stage IIA, 7 patients; and, stage III, 27 patients. No patients had distant metastases. Median follow-up for all patients was 3.2 years (range, 0.3-20.9 years). Median follow-up for survivors was 6.7 years (range, 1.6-20.9 years).

The 5-year outcomes were as follows: local control, 91%; regional control, 79%; local-regional control, 77%; disease metastasis-free survival, 60%; cause-specific survival, 53%; and overall survival, 39%. The 5-year outcomes for patients with stage I-IIA versus stage-III disease were the following: local-regional control, 90% versus 57% (p = .0115); distant metastasis-free survival, 78% versus 36% (p = .0002); cause-specific survival, 68% versus 35% (p = .0050); and overall survival, 48% versus 27% (p = .0377). Local-regional recurrences occurred in 12 patients; no patients were successfully salvaged. Severe late complications were observed in four patients.

Although radiotherapy alone or combined with surgery results in a relatively high likelihood of local-regional control, the majority of recurrences are distant and approximately half of patients are cured. Patients with regional disease at diagnosis have significantly worse outcomes.