Epidemiology and survival of Merkel cell carcinoma in the Netherlands. A population-based study of 808 cases in 1993-2007

Background

Merkel cell carcinoma (MCC) is a rare and highly malignant neuroendocrine tumour, predominantly located on sun-exposed areas of the skin. The aim of this study was to evaluate data in the Netherlands concerning incidence, stage, age, sex, location, treatment and survival.

Methods

Using nationwide data from the Netherlands Cancer Registry from 1993 to 2007, we compared 808 MCCs with European data and the US Surveillance, Epidemiology and End Results (SEER) Program.

Results

The annual age standardised incidence rate per million of MCC increased from 1.7 in 1993-1997 to 3.5 in 2003-2007. Median age at diagnosis was 76 years. The most common location was the head and neck. Three quarters of patients had localised disease, 16% regional and 6% distant metastasis. Surgery was performed in 89% of patients, with adjuvant radiotherapy in 26% of them. One-, five- and ten-year relative survival was 85%, 62% and 47%, respectively. Negative predictive factors for the risk of death were male sex, increasing T-stage, regional and distant metastasis and no treatment. Survival after combined surgery and radiotherapy was borderline significantly better than surgery alone (HR 0.82, p = 0.09). Our results are comparable to SEER data except for the ratio localised/regional disease. We observed less regional cases (16% versus 31%); while ten-year survival of localised cases was lower (51% versus 71%).

Conclusions

MCC incidence rates have doubled in the Netherlands over the period 1993-2007. The relatively high number of localised cases and their relatively low survival as compared to SEER data suggest that a substantial proportion is undertreated.