Collecting Duct Carcinoma of the Kidney: Analysis of Our Experience at the SPANISH ‘Grupo Centro’ of Genitourinary Tumors

Introduction: Collecting duct carcinomas (CDC), also known as Bellini’s tumors, are a rare and aggressive subtype of renal cell carcinoma. Therefore, there are very few data about their management, and there is no standard therapy for this malignancy. We report the outcome of CDC patients treated on institutions belonging to the ‘Grupo Centro’ of Genitourinary Tumors, a novel networking cooperative group in Spain. Material and Methods: Patients with CDC diagnosed between 1995 and 2015 were included. They had to have an appropriate follow-up, as well as available tissue for further correlative studies. Demographic baseline features and therapy outcomes were collected in a retrospective fashion. Approval for this data collection was obtained from a central ethical committee. Results: A total of 43 patients were analysed, with a median overall survival (OS) of 14 months (95% CI: 9.2–18.8 months). 29 of them (67.4%) were diagnosed as localized disease, and 14 (32.6%) as metastatic disease. For the subgroup of patients diagnosed without metastases, median relapse-free survival (RFS) is 22 months (95% CI: 12.4–35.6 months), and median OS, 53 months (95% CI: 35.5–84.3 months). For the subgroup of patients with metastatic disease, median OS is 6 months (95% CI: 4.1–7.8 months). 16 patients (55.2%) with stage IV disease received systemic therapy, mainly platinum-based chemotherapy, with a response rate of 12.5% and a median progression-free survival (PFS) of 2 months. Conclusions: CDC of the kidney is a malignancy with poor prognosis and few responses to therapy. Median OS of our group in the metastatic setting is similar to what has been observed in previous series. There is a clear need to improve the armamentarium we have for the systemic approach of patients with advanced CDC.