Multimodal Treatment of Nodal Localizations from Merkel Cell Carcinoma with No Identifiable Primary Site and Distant Metastases

e19020 Background: Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma. In sporadic cases nodes represent the only site of disease, anecdotally due to a spontaneous regression of the primary cutaneous tumor. Besides differential diagnosis primary/metastatic nodal localization is debated. No standard treatment exists in this setting. We report our multimodal management. Methods: Among patients with MCC examined at European Institute of Oncology of Milan between October 1995 and March 2009, we selected those with nodal involvement without evidence of primary tumor. Then we considered: histological diagnosis at IEO, no visceral sites of disease, staging with CT ± fluorodeoxyglucose (FDG) positron emission tomography (PET) ± somatostatin receptor scintigraphy (SRS), multidisciplinary discussion. We evaluated staging, multimodality, time to progression (TTP), median overall survival (mOS). Results: Among a total of 83 patients 28 had the above mentioned characteristics. All patients were staged with CT. A FDG-PET was positive for staging in 14/17 patients, and SRS in 12/17. Concordance FDG-PET/SRS was positive in 8 and negative in 1 cases. In 2 cases PET positive/SRS negative occurred. Thirteen patients underwent excisional biopsy, without lymphadenectomy. Six received chemoradiation, 3 chemotherapy, 1 chemo-biotherapy, 1 radiotherapy, 2 no treatment. Fifteen patients underwent lymphadenectomy, 7 with adjuvant chemoradiation, 4 chemotherapy, 1 radiation, 1 with neoadjuvant chemotherapy, 1 no further treatment, and 1 too early. With 22 months median follow-up median TTP was 17 months (95%CI: 7-NE). Median OS was 29 months (95%CI: 15-NE). TTP and mOS for patients underwent lymphadenectomy were not reached vs. 9 months (95%CI: 4-NE; p = 0.35) and 29 months (95%CI: 11.7, NE; p = 0.34) for patients without lymphadenectomy, respectively. Conclusions: In patients with nodal localizations of MCC without evidence of primary tumor and distant metastases lymphadenectomy improved TTP and mOS. FDG-PET for staging seems to be more accurate than SRS. The role of a multimodal therapeutic strategy should be studied in prospective trials. No significant financial relationships to disclose.