Associations of dietary isothiocyanate exposure from cruciferous vegetable consumption with recurrence and progression of non-muscle-invasive bladder cancer: findings from the Be-Well Study.

Background: High recurrence and progression rates are major clinical challenges for non-muscle-invasive bladder cancer (NMIBC). Dietary isothiocyanates (ITCs), phytochemicals primarily from cruciferous vegetables (CV), show strong anticancer activities in preclinical BC models, yet their effect on NMIBC prognosis remains unknown.

Objectives: This study aimed to investigate the associations of dietary ITC exposure at diagnosis with NMIBC recurrence and progression.

Methods: The study analyzed 1143 participants from the Be-Well study, a prospective cohort of newly diagnosed NMIBC cases in 2015-2019 with no prior history of BC. Dietary ITC exposure was indicated by self-reported CV intake, estimated ITC intake, urinary metabolites, and plasma ITC-albumin adducts. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for recurrence and progression, and unconditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for delayed and multiple recurrence.

Results: Over a mean follow-up of 25 mo, 347 (30%) developed recurrence and 77 (6.7%) had disease progression. Despite no significant associations with the overall risk of recurrence, urinary ITC metabolites (OR: 1.96; 95% CI: 1.01, 4.43) and dietary ITC intake (OR: 2.13; 95% CI: 1.03, 4.50) were associated with late recurrence after 12-mo postdiagnosis compared with before 12-mo postdiagnosis. Raw CV intake was associated with reduced odds of having ≥2 recurrences compared with having one (OR: 0.34; 95% CI: 0.16, 0.68). Higher plasma concentrations of ITC-albumin adducts were associated with a reduced risk of progression, including progression to muscle-invasive disease (for benzyl ITC, HR: 0.40; 95% CI: 0.17, 0.93; for phenethyl ITC, HR: 0.40; 95% CI: 0.19, 0.86).

Conclusions: Our findings indicate the possible beneficial role of dietary ITCs in NMIBC prognosis. Given the compelling preclinical evidence, increasing dietary ITC exposure with CV intake could be a promising strategy to attenuate recurrence and progression risks in patients with NMIBC.