Rising incidence of Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare, aggressive, skin cancer of obscure histogenesis, the incidence of which is rising. There is no consensus on the optimal treatment. Our aim was to evaluate the staging, investigation, treatment, and follow-up of MCC in eastern Denmark, and to investigate the incidence. We suggest guidelines for treatment. First we reviewed the medical records of 51 patients diagnosed with MCC from 1995 until 2006 in eastern Denmark. The nation-wide incidence of MCC was extracted from the Danish Cancer Registry for the calculations for the period 1986-2003. We reviwed published papers about MCC based on a MEDLINE search. Fourteen of the 51 patients developed recurrence, and 37 (73%) died during the study period. Mean follow-up was 13 months (range 1-122). A total of 153 patients were identified in the Danish Cancer Registry, and showed that incidence rates had increased 5.4 fold over the 18 year period from 1986 until 2003. Rates were highest in people over the age of 65. Recommended treatment with curative intent includes excision of the primary tumour with wide margins, excision of the sentinel node, computed tomogram (CT) or positron emission tomography (PET) of the thorax and abdomen, and adjuvant radiotherapy to the surgical bed. In the case of advanced disease, systemic palliative chemotherapy remains a possibility. There is a need for prospective multicentre evaluation of staging investigations and treatment of MCC.