Merkel cell cancer: update on biology and treatment

This review highlights the most important developments in the biology and treatment of Merkel cell carcinoma published in the medical literature over the past year.

Adjuvant radiotherapy to the primary site with or without coverage of the nodal region is recommended in most older series, although a risk-adapted approach is more reasonable. Sentinel lymph node biopsy should be considered in all cases irrespective of primary size. If not feasible, prophylactic regional radiotherapy is recommended as the risk of regional relapse without nodal staging is about 45%. Adjuvant radiotherapy to nodal regions after lymphadenectomy is not studied in detail, but there is a suggestion from many series that the recurrence rate is high enough to justify its use. Recent research has revealed that adjuvant chemotherapy currently has no established role in the treatment of localized node-negative Merkel cell carcinoma. Its use in pathologically node-positive or recurrent cases requires further study.

Given the lack of randomized evidence and heterogeneity in published retrospective series, clinical judgment is required to assess risk factors of an individual patient to make treatment decisions.