Merkel cell carcinoma arising in the head and neck: optimizing therapy.

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine dermal neoplasm. Because of the limited number of cases described in the literature (approximately 600 to date), statistically significant data regarding treatment are difficult to obtain. The majority of MCC cases affect the head and neck and are thought to be caused by the actinic damage associated with sun exposure. This study evaluates cases of head and neck MCC at Naval Medical Center San Diego (NMCSD) and compares the treatment regimens and outcomes from multiple institutions. This study is a retrospective outcomes analysis of all cases of head and neck MCC seen at NMCSD, between January 1, 1988 and June 30, 1998. The records of the NMCSD Tumor Registry were searched for patients with that diagnosis, and supplemental information was retrieved from the Radiation Oncology and Head & Neck Surgery Clinic charts. Eight of nine patients in this study were treated with either wide-local excision or Mohs microsurgery. The surgical margins were free of disease in all eight patients. One patient presented with distant metastatic disease, and two others were subsequently found to have nodal involvement. Subsequent therapy varied among the patients. Survey of the available literature revealed inconsistency in terms of which treatment regimens are optimal. Tumor resections are recommended by most groups to include a 2-cm to 3-cm tumor-free margin around the primary lesion when possible, but this is often difficult to achieve in the head and neck. Data, which do not reach statistical significance, suggest improved outcomes with tumor-free margins. Treatment of the regional draining lymph nodes is also recommended in most series. Prophylactic lymph node dissection or radiation therapy to the nodal chain may decrease local recurrence but does not consistently affect overall survival. Adjuvant chemotherapy is advocated by most groups in the treatment of metastatic disease because MCC is pathologically similar to small-cell lung carcinoma. However, no chemotherapy protocol has been shown to improve survival. Head and neck MCC is a rare and aggressive dermal tumor of neuroendocrine origin that requires multimodality therapy, including surgery, radiation therapy, and possibly adjuvant chemotherapy. Multiinstitutional studies are crucial to obtain sufficiently large populations to investigate and optimize therapy in this disease.