Tumor Morphology as a Risk Factor for Muscle Invasiveness in Newly Diagnosed Bladder Cancer: A Stratified Analysis

To investigate the association between tumor morphology and muscle-invasive bladder cancer (MIBC) in patients with newly diagnosed bladder cancer (BC).

This retrospective study included 416 patients who underwent transurethral resection of a bladder tumor for newly diagnosed BC between January 2018 and December 2023 at a tertiary hospital in Vietnam. Multivariable logistic regression analysis was applied to assess the adjusted association between the sessile morphology of BC on cystoscopy and the risk of muscle invasion. Age, sex, tumor size, number of tumors, and pathological grade were considered confounders. Stratified analysis by tumor size and number of tumors was performed to clarify the effect modification.

Patients with MIBC had a significantly higher prevalence of sessile morphology (68.8% vs. 28.4%, p<0.001). After controlling for confounders, patients with sessile tumors were three times more likely to have MIBC than those with papillary tumors (OR = 3.1, 95% CI = [1.8-5.3], p < 0.001). The association of sessile tumor with MIBC was higher in patients with tumor ≤3 cm (about 25%, OR = 3.9, 95% CI = [1.9-7.8]) and having >3 tumors (about 64%, OR = 5.1, 95% CI = [2.1-12.4]).

Sessile morphology is associated with the risk of MIBC in patients newly diagnosed with BC. This association was more pronounced in patients with tumor ≤3 cm and >3 tumors.