The Effects of a Dietary Regimen Characterized by High Consumption of Cruciferous Vegetables on Recurrence-free Survival in Patients With Intermediate, High and Very High-risk Non-Muscle Invasive Bladder Cancer: a Randomized Trial

Background Bladder cancer (BC) ranks as the seventh most common cancer among men globally and the tenth when both genders are considered. The majority (up to 75%) of newly diagnosed BC presents as non-muscle-invasive BC (NMIBC) including Ta (non-invasive papillary carcinoma confined to the mucosa), CIS (Carcinoma in Situ, a flat, high grade, non-invasive urothelial carcinoma) and T1 (tumor invasion of the sub-epithelial connective tissue) disease stage. NMIBC has a high prevalence due to low progression rates and long-term survival, representing a significant burden on both public health and individual well-being. The prevalence of urothelial BC is among the highest for all urologic malignancies. Although the understanding of genetic susceptibility is growing steadily, no clinically relevant genetic alteration has been linked to BC up to date, and family history seems to have little impact on BC risk. Conversely, most BC cases are associated with external exposure to carcinogens. Supportive evidence has been reported on several risk factors: tobacco smoking alone accounts for approximately 50% of events. In contrast, occupational exposure (mostly involving aromatic amines, polycyclic, and chlorinated hydrocarbons) represents the second most common risk factor in industrialized countries. Environmental exposure (e.g., trihalomethanes and arsenic in drinking water) and pelvic radiation have been linked to an increased risk of developing BC. In light of the significant impact of modifiable risk factors on the incidence of BC, implementation of primary prevention strategies can lead to a decrease in BC risk: in the "Women's Health Initiative (WHI) Study" a decrease in BC risk was demonstrated after smoking cessation. Likewise, work-safety guidelines have been prompted to reduce the extent of professional exposure in developed industrial settings, thus eliminating the difference in BC incidence between chemical workers and the general population. Primary interventions targeting exposure and lifestyle changes have become central to public health strategies aimed at mitigating the burden of bladder cancer. In the broader landscape of primary prevention, dietary habits play a crucial role in reducing the risk of bladder cancer. Emerging evidence highlights the importance of nutrition in modulating cancer-related pathways, suggesting that specific dietary patterns and food choices may influence cancer risk. A protective role has been suggested for high consumption of vegetables, non-saturated fat oil (Mediterranean diet), fruits, and flavonoids. In contrast, a diet rich in saturated fats and meat has been linked to an increased risk of BC. Particularly, the consumption of vegetables of the Cruciferae family, such as broccoli, cauliflower, brussels sprouts, cabbage, kale, turnips, and others, has gathered attention for their potential protective effects due to their bioactive compounds: Isothiocyanates (ITCs). Dietary ITCs are a group of phytochemicals with multifaceted anticancer mechanisms primarily derived from cruciferous vegetables (CV) as glucosinolates and converted to ITCs by the action of the enzyme myrosinase. Organic ITCs, particularly allyl isothiocyanate (AITC), benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC), and sulforaphane (SF), are among the most extensively studied cancer chemopreventive agents. Several mechanisms for ITCs in protection against carcinogenesis have been proposed, which include inhibition of carcinogen activation and promotion of detoxification, induction of cell cycle arrest and activation of apoptosis, inhibition of cancer cell invasion, modulation of the tumor microenvironment, inhibition of self-renewal of stem cells, rearrangement of energy metabolism and regulation of microbial homeostasis. Several in vitro, in vivo, and epidemiologic studies have shown that a diet rich in vegetables in the Cruciferae family may lower overall cancer risk for breast, colorectal, lung, and prostate cancer. The important role of dietary ITCs has been demonstrated in reducing BC risk and BC-specific mortality. In vitro, the 4 most common dietary ITCs and their primary urinary metabolites showed inhibition of growth of a panel of human bladder cancer cells, including NMIBC cells, with half-maximal inhibitory concentration (IC50) values around 10 µmol on average, which is achievable in the urine with a single oral dose of ITC at 10 µmol/kg in rats, also readily achievable in humans, considering an average total isothiocyanate yield in Cruciferae of 16.2 μmol/100g wet weight. By increasing Cruciferae intake by 1 cup a day, the urinary concentration of ITCs increases on average by 10.4 µmol, the desirable dose level of urinary ITCs needed to stop or kill at least 50% of bladder cancer cells in in vitro models. Orally ingested ITCs are rapidly and almost exclusively delivered to the bladder and concentrated in the urine, showing concentration 2 or 3 times higher in the urine than in the plasma within 3 hours of dosing. This unique in vivo metabolism and disposition pathway renders the bladder the best target for ITCs' anticancer potential. In the Bladder Cancer Epidemiology, Wellness, and Lifestyle Study (Be-Well study), a multicenter prospective cohort study on newly diagnosed NMIBC, a possible beneficial role of dietary ITCs in NMIBC prognosis was assessed: despite no overall association between dietary ITC intake and recurrence risk was found, high ITC intake was linked to over twice the odds of late recurrence, while high raw cruciferous vegetable intake reduced the odds of multiple recurrences by 50%-60%, and elevated BITC and PEITC biomarkers were associated with >50% lower risk of muscle-invasive progression. In the same study group, the impact of dietary ITC exposure was assessed in relation to the efficacy of intravesical Mitomycin (MMC) chemotherapy or Bacillus Calmette-Guérin (BCG) immunotherapy on the risk of recurrence. In a stratified analysis, patients who received BCG and consumed high amounts (>2.4 servings/month with 1 serving corresponding to half a cup of non-leafy vegetables or 1 cup of leafy vegetables) of raw CVs had at least a 44% reduced risk of recurrence and multiple recurrences, which was not observed in those consuming low doses of row CV. In a randomized controlled setting, this study aims to assess the impact of CV intake and ITC exposure on recurrence risk in patients with NMIBC undergoing BCG intravesical immunotherapy.

Hypothesis Primary interventions targeting exposure and lifestyle changes have become central to public health strategies aimed at mitigating the burden of bladder cancer. In the broader landscape of primary prevention, dietary habits play a crucial role in reducing the risk of bladder cancer. Emerging evidence highlights the importance of nutrition in modulating cancer-related pathways, suggesting that specific dietary patterns and food choices may influence cancer risk. A protective role has been suggested for high consumption of vegetables, non-saturated fat oil (Mediterranean diet), fruits, and flavonoids. In contrast, a diet rich in saturated fats and meat has been linked to an increased risk of BC. Particularly, the consumption of vegetables of the Cruciferae family, such as broccoli, cauliflower, brussels sprouts, cabbage, kale, turnips, and others, has gathered attention for their potential protective effects due to their bioactive compounds: Isothiocyanates (ITCs). Dietary ITCs are a group of phytochemicals with multifaceted anticancer mechanisms primarily derived from cruciferous vegetables (CV) as glucosinolates and converted to ITCs by the action of the enzyme myrosinase. Organic ITCs, particularly allyl isothiocyanate (AITC), benzyl isothiocyanate (BITC), phenethyl isothiocyanate (PEITC), and sulforaphane (SF), are among the most extensively studied cancer chemopreventive agents. Several mechanisms for ITCs in protection against carcinogenesis have been proposed, which include inhibition of carcinogen activation and promotion of detoxification, induction of cell cycle arrest and activation of apoptosis, inhibition of cancer cell invasion, modulation of the tumor microenvironment, inhibition of self-renewal of stem cells, rearrangement of energy metabolism and regulation of microbial homeostasis.

Aims Primary Objective

• To evaluate the effect, in terms of recurrence-free survival (RFS) at 1 year, of a dietary regimen characterized by high consumption of the Cruciferae family vegetables versus no dietary regimen in patients with Intermediate, High, or Very High-grade Non-Muscle Invasive Bladder Cancer treated with BCG (defined as the standard of care - SOC).

Secondary Objectives