Merkel cell carcinoma--current therapeutic options.

Merkel cell carcinoma (MCC) is a rare, highly malignant skin tumour of neuroendocrine origin that occurs predominantly in elderly people in sun-exposed areas. It exhibits high levels of radiosensitivity and chemosensitivity both in vivo and in vitro. A variety of adverse prognostic factors have been identified which allow more aggressive therapy to be delivered to patients who are at higher risk of recurrence. The most powerful prognostic factor is the presence of nodal secondaries. Local disease should be excised, but there is some controversy over how wide the margins should be. Wide resection margins are not required provided postoperative radiotherapy is used. In the event of inoperable disease, patient refusal of surgery or frailty, radiotherapy can be used as the sole treatment modality, with a high likelihood of achieving local control. Patients with involved nodes have a higher risk of distant disease. Traditionally, involved nodes have been managed with resection but, currently, there are protocols exploring the use of synchronous chemoradiotherapy as definitive treatment. Although adjuvant chemotherapy has been used in this setting to reduce the risk of distant metastases, its role still remains under investigation. The presence of distant disease carries a grave outlook with responses to chemotherapy occurring frequently, albeit of short duration.