Successful Targeted Radiotherapy with 90Y-DOTATOC in a Patient with Merkel Cell Carcinoma

Merkel cell carcinomas (MCC) belong to the family of neuroendocrine tumors. In addition to other markers, they express somatostatin receptors. They are uncommon, highly malignant skin tumors with an aggressive clinical course. They develop in sun-exposed areas of the skin, mostly in elderly patients. In addition to frequent locoregional recurrences, there is a high incidence of distant metastases. Treatment is stage dependent and consists of operation and chemo- and/or radiotherapy, respectively. The advanced age of patients often impedes adequate therapy. 90 Y-DOTATOC is a novel radiolabeled somatostatin analogue containing the active octapeptide of somatostatin. It is very well tolerated and offers the option of treating somatostatin receptor-positive tumors by targeted radiotherapy. We report the case of an 83-year-old woman with recurrent MCC of the left cheek. The primary tumor and several relapses were treated with surgery and locoregional radiotherapy. After the 3rd relapse, she was treated 4 times with 90 Y-DOTATOC and two complete remissions were achieved. The fourth administration after the 2nd relapse was ineffective and conventional chemotherapy was started. There were no side effects of the 90 Y-DOTATOC. We conclude that due to its good tolerability, 90 Y-DOTATOC therapy should be evaluated further as a new therapy for somatostatin receptor-positive MCC.