Outcomes of a Dietary Intervention to Reduce Bladder Cancer Recurrence and Progression in Survivors of Non–Muscle-Invasive Bladder Cancer

Abstract

Background: As one of the 10 most common cancers in the United States, bladder cancer is the most expensive cancer to treat. Most bladder cancers (70%–80%) are diagnosed at early stages as non–muscle-invasive bladder cancer (NMIBC), which can be removed. However, 50% to 80% of NMIBC recurs within 5 years, and 15% to 30% progresses with poor survival. Besides life-long surveillance, current treatment is limited. Preclinical and epidemiologic evidence suggest that dietary isothiocyanates (ITCs) in cruciferous vegetables (Cruciferae) could be a noninvasive and cost-effective strategy to improve NMIBC prognosis. Yet, a Cruciferae intervention that increases ITC exposure in NMIBC survivors has not been tested. Thus, the primary aim of this study was to test the effect of a Cruciferae intervention on urinary ITC levels and Cruciferae intake in NMIBC survivors. Patients and Methods: We conducted a 2-arm, double-blinded, randomized controlled trial to test the efficacy of a Cruciferae intervention against a general fruit and vegetable intervention (control) for NMIBC survivors. Both 6-month interventions consisted of mailed educational materials, a live call with staff to review the materials, and 11 interactive voice response calls. We anticipated that our Cruciferae intervention (Power to Redefine Your Health [POW-R Health]) would increase Cruciferae intake to 1 cup/day (secondary outcome), thus raising urinary ITC levels to 10 µM (primary outcome) from baseline to 6-month follow-up. Results: We randomized 49 patients with NMIBC diagnosed in 2018 through 2019, and retained 42 patients at 6-month follow-up. The treatment group reported 0.94 cups (95% CI, 0.24–1.65; P=.010) higher Cruciferae intake (treatment, 1.37 ± 1.19 cups vs control, 0.56 ± 0.72 cups) and increased urinary ITC levels by 11.1 μmol/g creatinine (treatment, 26.2 ± 20.9 vs control, 7.8 ± 11.5; P=.027) at 6-month follow-up compared with the control group. Conclusions: Our dietary intervention is the first to significantly increase Cruciferae intake and urinary ITC levels in NMIBC survivors, demonstrating an increase in ITC to levels that significantly decrease risk of disease-specific survival. A future randomized controlled trial testing POW-R Health on bladder cancer recurrence and progression is warranted. If proven to improve bladder cancer outcomes, our intervention has the potential to be a noninvasive, cost-effective, easily accessible way for NBMIC survivors to improve their bladder cancer prognosis.