Single bladder instillation of gemcitabine versus mitomycin C after minimally invasive radical nephroureterectomy: A propensity-score match analysis from the ROBUUST 2.0 collaborative group.

Objective: Radical nephroureterectomy (RNU) is considered the standard of care for patients with high-risk upper tract urothelial carcinoma. Current literature reveals a deficit in direct comparative studies evaluating the efficacy of different chemotherapeutic agents administered in single postoperative instillation following RNU. The primary aim of this study was to compare the bladder recurrence (BR) rates between patients receiving a single instillation of mitomycin C (MMC) versus gemcitabine (Gem) after RNU. Methods: The ROBUUST (ROBotic surgery for Upper tract Urothelial cancer STudy) 2.0 is an international, multicenter registry that aggregates data on patients who have undergone curative surgery for upper tract urothelial carcinoma across participating centers from January 2015 to December 2022. Data including primary baseline variables of the patients, characteristics of the tumors, surgical management, and definitive histopathological characterizations were collected and stratified based on the type of postoperative bladder instillation: MMC (the MMC group) and Gem (the Gem group). We selected variables correlated with our primary outcome to conduct a propensity-score match analysis. Results: One hundred patients in the MMC group were matched 1:1 with 100 patients in the Gem group. At 36 months of follow-up, 30 patients in the MMC group and 39 patients in the Gem group experienced BR, representing recurrence rates of 30% and 39%, respectively (p=0.2). The Cox proportional hazards model comparing BR between the groups revealed a hazard ratio of 1.58 (95% confidence interval: 0.98-2.55) with a non-statistically significant increased risk of BR in the Gem group compared with the MMC group (p=0.059). Conclusion: A single perioperative instillation of Gem or MMC seems to offer similar efficacy in reducing the risk of BR in patients undergoing RNU. Further research, ideally within the framework of prospective studies, is warranted to elucidate the optimal chemotherapeutic approach in this setting.