Merkel cell carcinoma demographics, morphology, and survival based on 3870 cases: a population based study.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor arising predominantly on sun-exposed skin of older and usually immunosuppressed individuals. METHODS: Using data from NCI's SEER (Surveillance, Epidemiology, and End Results) Program from 1973 to 2006, we analyzed the demographics and survival of MCC. RESULTS: SEER had recorded 3870 cases of MCC. The incidence was higher in men (2380 cases, 61.5%) than in women (1490 cases, 38.5%). Most patients were White (94.9%) between 60 and 85 years of age. MCC was rare in Blacks. The most common location was the head and neck. The salivary glands, nasal cavity, lip, lymph nodes, vulva, vagina and esophagus were the most common extracutaneous sites. The 10-year relative survival rate was higher in women than men (64.8% vs. 50.5%, p < 0.001). Patients 50-69 years had the highest 10-year relative survival rate (59.6%). Stage of disease was the best predictor of survival. CONCLUSIONS: MCC arises predominantly in the skin of head and neck in White men above 70 years of age. Cases also occurred in extracutaneous sites. Age did not predict survival, yet gender, site and tumor size revealed clear differences. The most significant predictor of survival was tumor stage.