Discrimination of T-Stage Using Tumor Weight and Size: A Potential Approach to Guide Perioperative Decision-Making in Patients with Bladder Cancer.

Introduction: The aims of the study were to examine the value of tumor size, weight, and density in predicting pathological tumor stage in patients with suspected bladder cancer (BCa), minimize inter-observer variability of estimated tumor size, and thus provide a more objective instrument to describe the extent of local tumor growth.

Methods: An institutional dataset of 588 consecutive patients undergoing transurethral resection of bladder tumor (TUR-BT) for suspected BCa from 05/2016 to 09/2018 was used. Separate Mann-Whitney U tests examined differences in each unit between non-muscle-invasive BCa (NMIBC) and muscle-invasive BCa (MIBC) and between Ta/carcinoma in situ and T1 NMIBC. Intraoperative tumor size, weight, and respective density were calculated. We then calculated multivariable logistic regression models to examine each unit's predictive value and distinguish between endpoints.

Results: Overall, 367 patients undergoing TUR-BT were diagnosed with BCa. In patients with MIBC (n = 73), the median size (p < 0.001) and weight (p < 0.001) were higher compared to NMIBC. In contrast, tumor density (p < 0.001) was lower. On multivariable analysis, increasing size and weight were associated with higher odds of T1 (size: odds ratio [OR] 2.50, 95% confidence interval [CI]: 1.87-3.35; weight: OR 1.65, 95% CI: 1.26-2.15) and muscle-invasive disease (size: OR 1.51, 95% CI: 1.29-1.78; weight: OR 1.09, 95% CI: 1.03-1.15). Meanwhile, an increasing density was associated with lower odds of both outcomes (T1: OR 0.96, 95% CI: 0.89-1.02; MIBC: OR 0.81, 95% CI: 0.69-0.96).

Conclusion: In patients diagnosed with BCa, tumor size, and weight showed similar predictive power concerning T1 NMIBC and MIBC. Tumor density failed to predict the local tumor stage sufficiently. These results may lay the foundation for improving objective measurement of the local tumor burden in patients with BCa and may help guide further immediate treatment decisions.