Merkel cell carcinoma adjuvant therapy: Current data support radiation but not chemotherapy

August 19, 2007

Publisher

Journal of the American Academy of Dermatology

Publication Date

August 19, 2007

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Merkelcell.org Summary

Dr. Nghiem and Kelly Garneski publish a paper on the role of chemotherapy in MCC.

Abstract

Merkel cell carcinoma is a skin cancer with 30% mortality and an incidence that has tripled in the past 15 years. There is agreement that surgical excision with negative margins is an appropriate therapeutic first step and that sentinel lymph node biopsy is a powerful prognostic indicator. Following excision of detectable cancer, optimal adjuvant therapy is not well established. A role for adjuvant radiotherapy is increasingly supported by retrospective data suggesting a nearly four-fold decrease in local recurrences if radiation is added to surgery. In contrast, a role for adjuvant chemotherapy is not well supported. The rationale for chemotherapy in this disease is based on small-cell lung cancer, a more common neuroendocrine tumor for which chemotherapy is the primary treatment modality. Several issues call into question the routine use of adjuvant chemotherapy in Merkel cell carcinoma: lack of evidence for improved survival; the associated morbidity and mortality; important differences between small-cell lung cancer and Merkel cell carcinoma; and rapid development of resistance to chemotherapy. Importantly, chemotherapy suppresses immune function that plays an unusually large role in defending the host from the development and progression of Merkel cell carcinoma. Taken together, these arguments suggest that adjuvant chemotherapy for Merkel cell carcinoma patients should largely be restricted to clinical trials.

Merkel cell carcinoma is a neuroendocrine cancer that typically presents as a rapidly growing non-specific nodule on sun exposed skin in people over 65 years of age. The recent increase in incidence to over 1000 cases a year in the United States has led Merkel cell carcinoma to become the second most common cause of non-melanoma skin cancer death. Optimal management for Merkel cell carcinoma beyond surgical excision is not agreed on, and no randomized trials have been carried out. Sentinel lymph node biopsy has been shown to be powerful in predicting subsequent recurrences as well as in determining if further nodal treatment is indicated.

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