Clinical characteristics of patients with collecting duct carcinoma.

Abstract

297 Background: Collecting duct carcinoma (CDC) is traditionally classified as a rare renal cell carcinoma. It comprised less than 2% of all renal cell carcinoma but presented a highly aggressive clinical course1. The natural history of CDC was merely described in small-sample retrospective studies because of its low incidence. Methods: We retrospectively collected clinicopathological data of patients (pts) diagnosed with CDC in our center from 2006 to the present. Histological diagnoses of all patients with CDC were confirmed by two senior urologic pathologists. Results: CDC was found in 58 pts (60% males and 22% over 65 years old). Most started with hematuria, low back pain, or systemic symptoms; 7 pts (12%) had no clinical symptoms. 67% pts underwent partial or radical resection of the kidney. 39.7% pts had distant metastases at diagnosis. Among the 35 pts with no distant metastasis at diagnosis, 18 (51%) had positive regional lymph nodes, 22 (63%) had locally advanced T stage (T3 or T4), and 18 (51%) were G3/4 by Fuhrman or WHO/ISUP. For pts undergoing radical nephrectomy, the median disease-free survival (DFS) was 6.3 mos (95%CI: 0.2, 12.4), and the median OS was 22.5 mos (95%CI: 16.6, 28.4), which were significantly related to T stage (P = 0.033 and 0.001). For pts after metastasis (56 cases), the most common sites of recurrence and metastasis were lymph nodes (55%), lung (46%), bone (36%), liver (16%), adrenal glands (7%), and local recurrence (20%). The median OS after metastasis was 11.3 mos (95%CI: 9.5, 13.0). Among the locally advanced or metastatic pts, 33 received gemcitabine + cisplatin combined with sorafenib as the first-line therapy. There were 8 PR and 17 SD. The ORR was 24.2%, DCR was 75.8%, and median PFS was 6.1 mos (95% CI: 4.7, 7.5). The median OS was 12.1 mos (95% CI: 8.6, 15.5). In 2 pts receiving anti-PD-1 monoclonal antibody combined with axitinib, 1 case had PR and 1 obtained SD with tumor shrinking. They are still under follow-up. Conclusions: CDC is prone to be diagnosed at a late stage and develop metastases. There is currently no standard treatment for metastatic patients; gemcitabine + cisplatin combined with sorafenib can be tried in the first-line setting. Anti-PD-1 plus axitinib showed promising efficacy in cases of CDC, and a larger sample is needed for verification.