Outcomes with multi parametric MRI (mpMRI) compared to diagnostic transurethral resection of bladder tumor (TURBT) in patients (pts) with suspected muscle-invasive bladder cancer (MIBC): A pilot study.

TPS881 Background: TURBT is a standard diagnostic procedure to determine the depth of bladder tumor invasion into the bladder wall, particularly whether the muscularis propria layer is involved by tumor. This is crucial in order to distinguish between non-MIBC and MIBC, providing accurate tumor staging and determining appropriate therapy. However, TURBT may be associated with multiple complications such as pain, infection, need for Foley catheters, blood loss requiring transfusions, hospitalization, and a small mortality risk. A proportion of pts end up with a superficial resection out of concern for bladder perforation, where the muscularis propria layer is absent from the surgical specimen, and require a repeat TURBT that is typically performed 4-6 weeks following the initial procedure. Further, TURBT scheduling requires coordination with urology and operating room availability. These factors may cause delays in initiation of cancer-directed therapy. Recent data suggests that mpMRI may accurately predict the degree of invasiveness of bladder tumors by generating a Vesical Imaging-Reporting and Data System (VI-RADS) score. mpMRI is not commonly associated with complications and can be performed quickly by radiology. Methods: This is an IRB-approved, single-institution, prospective, single-arm, phase 2 pilot study, which aims to compare two diagnostic modalities for bladder cancer - TURBT versus mpMRI. Pts are identified based on tumor appearance during initial routine cystoscopy, if MIBC is suspected. If eligible for the study, pts then proceed with an mpMRI and a diagnostic TURBT. Primary study endpoint is incidence of concordance between VI-RADS score 4 and 5 bladder tumors on mpMRI, which represent “likely” and "very likely" muscularis propria invasion, and pathologic muscularis propria invasion on TURBT. Secondary study endpoints include time from initial cystoscopy to performing each diagnostic test, time from performing each diagnostic test to initiation of cancer-directed therapy, incidence of repeat TURBT, patient-assessed quality of life with each diagnostic test, incidence of adverse events related to each diagnostic test, progression free survival, and financial toxicity of each diagnostic test. Based on prior literature, the rate of detecting muscularis propria invasion with TURBT is about 90%. We hypothesized that diagnostic accuracy of mpMRI would be non-inferior to TURBT, within a 10% difference. Power calculations for this study were based on a one-sided, one-proportion exact test, with a power of 80% at a significance level of 0.05 using a non-inferiority design. Out of 30 anticipated pts, 11 have been enrolled to date. Clinical trial information: NCT06335667 .