PD26-05: How long should we follow low grade Ta non-muscle invasive bladder cancer (NMIBC)? A large retrospective single institution analysis

Eunice Villegas, Christian Vitug, Katherine Lajkosz, Cynthia Kuk, Bruce Gao, Otto Hemminiki, Dhiral Kot, Shayan Din, Jimmy Misurka, Girish S. Kulkarni, Michael Jewett, Neil E. Fleshner, Theodorus H. van der Kwast, Alexandre R. Zlotta*, Toronto, Canada

Introduction: Over 50% of Ta low grade (LG) NMIBC will recur during long-term follow up but only a few percent will experience stage progression, metastases and death due to BC. For patients with TaLG NMIBC free of recurrence for 10 years, discontinuation of routine cystoscopic surveillance or replacement with urinary markers and/or ultrasonography has been considered as the recurrence rate drops after 5 years. We investigated the long-term follow-up of TaLG NMIBC to further define the length of monitoring.

Methods: We retrospectively analyzed 529 patients with primary TaLG NMIBC diagnosed between 1989-2019 and followed until 2021 using patient records and the Bladder Cancer Informatics System at the University Health Network, Canada. We assessed the risk of progression to high grade Ta/T1 NMIBC, progression to muscle-invasive disease, metastasis and risk of death due to BC at 5, 10 and 15 years using cumulative incidence functions. Non-BC death served as a competing risk for death due to BC, and all-cause death served as a competing risk for all other outcomes.

Results: Among 529 patients (73% men, median age 67.5years), 360(68%) recurred, 50(9%) progressed in stage, 20(4%) developed metastases and 15(3%) died from BC. Median follow-up was 9.4 years. 312/360(87%) patients recurred within the first 5 years. Of the 217 patients who did not recur within the first 5 years, 11 died due to non BC related causes. Of the remaining patients, 48(9% of the entire cohort) recurred. 36 patients (free of recurrence in the first 5 years) recurred within 10 years of their diagnosis, 9 recurred between 10-15 years and 3 between 15-20 years. Of the 15 patients who succumbed to BC (median 9.6 years; IQR3.6-14.8 years) despite presenting initially with TaLG disease, 80% were men, 10% had associated CIS, 67% had multiple tumors and 80% had tumors <3 cm. The actuarial CSS were 99%, 97% and 96% at 5, 10 and 15 years, respectively, whereas the progression to MIBC or metastases was 3, 5 and 6% at 5, 10 and 15 years. Limitations include the retrospective analysis and results obtained in a tertiary referral center might not be generalizable.

Conclusions: Surveillance of patients with TaLG NMIBC should definitely be continued beyond 5 years of follow-up and probably even beyond 10 years. Even after being free of recurrence for 5 years, about 10% of patients will recur. Although the risk is low, about 3% of patients presenting with TaLG NMIBC will eventually die from the disease, most in the intermediate risk category. The term “cancer” for TLGa NMIBC should therefore be kept in our opinion.

Source of Funding: N/A