Oncologic outcomes of intravesical therapy in the management of nonmuscle invasive bladder cancer with variant histology

Purpose: There is limited data on oncologic outcomes in nonmuscle invasive bladder cancer (NMIBC) with variant histology (VH) managed with intravesical therapy. We sought to evaluate oncologic outcomes for this cohort at a high-volume center. Materials and methods: A retrospective review of an IRB-approved bladder cancer database was performed. Patients with a history of NMIBC with VH present on transurethral resection of bladder tumor (TURBT) treated with intravesical therapy (BCG or chemotherapy) were identified. Outcomes of interest included recurrence within the bladder, progression to muscle-invasive bladder cancer (MIBC), metastatic progression, cancer-specific, and overall survival. Survival time was computed from the date of initiation of intravesical therapy to the date of event or censoring. For patients who underwent radical cystectomy, recurrence-free, cancer-specific, and overall survival were also computed. The Kaplan-Meier method with log rank was utilized to compare survival time between VH sub-groups. Results: Ninety patients were included in the final cohort with a median follow-up of 38 months. The majority of patients had T1 disease (72%) and received intravesical BCG (83%) as their only form of intravesical therapy. The most commonly represented VH in this series were glandular and squamous differentiation (26%). Forty-eight patients (53%) experienced recurrence within the bladder with a median recurrence-free survival of 24 months (95% Confidence Interval [CI]: 2–46 months). Five-year rates of progression to MIBC and distant metastasis were both 14% respectively. Twenty-six patients (28%) eventually required cystectomy. When stratifying by VH, patients with sarcomatoid, plasmacytoid, and micropapillary had significantly worse oncologic outcomes. Conclusion: In this series of highly-selected patients with NMIBC and VH, bladder-sparing treatment with intravesical therapy demonstrated acceptable oncologic outcomes for most VHs. This may be an acceptable treatment option for patients without plasmacytoid, sarcomatoid, or micropapillary features who are not suitable cystectomy candidates or who prioritize bladder-sparing treatment.