Postoperative continuous saline bladder irrigation reduces active urinary cancer cells: a prospective study in NMIBC.

Purpose: There is a lack of clinical evidence on whether further clinical strategies are needed after TURBT combined with immediate bladder instillation. This study intends to establish a reliable quantitative assay for active urinary cancer cells (AUCC) and to investigate the clinical efficacy of continuous saline bladder irrigation (CSBI) as a feasible option by analyzing the perioperative AUCC changes in TURBT.

Methods: An AUCC assay was developed and its reliability was verified by single-cell whole genome sequencing. Bladder cancer patients (N = 324) diagnosed by cystoscopy and pathologic biopsy and control individuals (N = 92) were included from 2021 to 2023 in the study. Enrolled patients with non-muscle invasive bladder cancer (NMIBC) underwent TURBT followed by immediate bladder instillation of epirubicin, after subgroups received CSBI or not, and AUCCs were tested on the first and fifth postoperative day. The patients were followed up for two years for postoperative recurrence.

Results: The AUCC assay achieved good detection accuracy, with a sensitivity of 0.821 and specificity of 0.902. AUCC increased on the first day after TURBT in combination with immediate bladder instillation, regardless of whether or not the patient received CSBI. However, AUCCs decreased more rapidly on the fifth day in patients treated with CSBI, and patients with concomitant risk factors benefited more from CSBI. The two-year follow-up results showed that high-risk patients with complex surgeries could benefit significantly from CSBI.

Conclusions: We pioneered a quantitative assay for AUCC and provided laboratory evidence that TURBT causes tumor cell dissemination and CSBI can be a further clinical strategy to reduce the risk of potential recurrence.