Incidence and pathological features of metachronous bladder cancer in prostate cancer patients treated with brachytherapy or radical prostatectomy in a single institution.

Abstract

111 Background: Although previous studies have reported that the incidence of metachronous bladder cancer (MBC) is not significantly different after brachytherapy (BT) compared to radical prostatectomy (RP), few studies have reported differences in the pathological features (PF) of MBC between them. This study was conducted to clarify differences in the incidence and PF of MBC between BT and RP in our hospital. Methods: We reviewed 504 patients treated with BT and 471 referred patients treated with RP from 2006 to 2017 in our hospital. We checked the incidence of MBC in all patients and examined the PF including the tumor number, location within the bladder, histology, and time from BT or RP to the occurrence. The chi-square test and Mann-Whitney U test were performed to analyze the differences between the two groups. Results: After a median follow-up time of 66 months, a total of 8 cases of BC occurred in the BT group (1.6 %) and 5 in the RP group (1.1 %). The median time from initial treatment to the occurrence of MBC was 56 months (12-121) in BT and 71 months (4-126) in RP (p = 0.622). Average tumor number was not significantly different (BT:1.38, RP: 2.2, p = 0.265). The incidence of MBC in each location within the bladder for BT vs. RP was 4 vs 0 in the right wall, 3 vs 0 in the left wall, 0 vs 3 in the posterior wall, 0 vs 2 in the dome, and 1 vs 0 in the trigone. The incidence in the lateral wall was significantly higher in BT than in RP (p = 0.00466). There were 3 muscle-invasive cases in BT and 1 case in RP (p = 1.00). High-grade urothelial cancer occurred more in BT 8 than in RP 1 (p = 0.00699). Conclusions: The risk of MBC after BT appeared to be equivalent to patients after RP. MBC after BT occurred more in the lateral wall with worse PF compared to those after RP.