Dermatologic Manifestations of Merkel Cell Carcinoma Treatment & Management

Updated: Nov 07, 2018
  • Author: Christopher R Shea, MD; Chief Editor: William D James, MD  more...
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Treatment

Medical Care

Various chemotherapeutic regimens have been used, but none has been proven to result in improved survival; the role of chemotherapy in the management of Merkel cell carcinoma (MCC) remains unclear. Merkel cell carcinoma is chemosensitive but only rarely chemocurable in patients with metastasis or locally advanced tumors. Moreover, chemotherapeutic toxicity leads to high mortality. [40]

Avelumab (Bavencio), an anti-PD-L1 IgG1 monoclonal antibody, was approved by the US Food and Drug Administration (FDA) in March 2017 for metastatic MCC in adults and pediatric patients aged 12 years or older.

Approval of avelumab was based on the JAVELIN Merkel 200 open-label, single-arm, multicenter study in 88 patients with histologically confirmed metastatic MCC whose disease had progressed on or after chemotherapy administered for distant metastatic disease. [41] The objective response rate was 33%, partial response was 22%, and complete response was 11%. Tumor responses were durable, with 86% of responses lasting at least 6 months (n=25) and 45% of responses lasting at least 12 months (n=13). Duration of response ranged from 2.8 to over 23.3 months.

Another PD1 inhibitor, pembrolizumab, has already shown efficacy in metastatic Merkel cell carcinoma. [42]

The role of radiation therapy (RT) in managing Merkel cell carcinoma remains controversial. RT may help control unresectable primary or metastatic lesions, and it may also be useful for local control when administered postoperatively to the primary site and the regional draining lymph node basin. Adjuvant RT reportedly reduces the local and regional recurrence rate but may not lead to improved overall survival. [43, 44, 45, 46]

Also see Guidelines.

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Surgical Care

Wide local excision (eg, with margins of 3 cm) is usually indicated if clinically feasible. Some have recommended Mohs micrographic surgery for its tissue-sparing effects and possible superior control of local disease; however, tumor deposits may be noncontiguous histologically, rendering this modality less effective in such cases. [47]

Selective lymphadenectomy (sentinel lymph node procedure) is becoming a standard approach for patients with Merkel cell carcinoma. While any effect on survival remains unclear, [48] it does provide valuable prognostic information since the presence of metastasis is the dominant risk factor for death from disease. Prophylactic complete lymph node dissection, combined with wide local excision and adjuvant radiotherapy, reportedly may improve survival. [49]

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Consultations

Early referral to a surgical oncologist, a medical oncologist, and a radiation therapist is indicated.

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Prevention

Photoprotection (eg, sunscreen, behavioral prevention) may help prevent Merkel cell carcinoma (MCC), but this is not proven. Also see Sunscreens and Photoprotection.

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