Plain language summary
Worldwide, almost 400,000 cases of bladder cancer are diagnosed each year, with 150,000 deaths, a high rate of recurrence and a high treatment cost. This review article evaluates the literature regarding the potential role of cruciferous vegetables (broccoli, cauliflower, cabbages, pak choi, watercress, wasabi are all examples of cruciferous vegetables) in bladder cancer prevention and as an adjunct to current treatment protocols. In vitro studies have shown inhibition of bladder cancer cell reproduction, stalled cancer cell cycles, and cancer cell death by compounds in cruciferous vegetables, in particular sulphoraphane (known to be high in broccoli and broccoli sprouts) and erucin (available in rocket for example). Studies show an inverse relationship between cruciferous vegetable intake and risk of bladder cancer, with those consuming 2 or more portions per week having a 39% lower risk of bladder cancer than those who consume less than 1 portion per week. The review also looks at cooking method, with steaming, stir-frying and sauteeing protecting the important nutrients when compared to boiling. The authors call for pre-clinical studies to be performed, examining multiple formulations of cruciferous vegetables in a variety of bladder cancer models, looking at prevention in high risk groups and adjuvant to standard treatment protocols. Nutrition Practitioners may want to consider including regular intake of cruciferous vegetables in their client protocols.
Abstract
Bladder cancer is a significant health burden due to its high prevalence, risk of mortality, morbidity, and high cost of medical care. Epidemiologic evidence suggests that diets rich in cruciferous vegetables, particularly broccoli, are associated with lower bladder cancer risk. Phytochemicals in cruciferous vegetables, such as glucosinolates, which are enzymatically hydrolyzed to bioactive isothiocyanates, are possible mediators of an anticancer effect. In vitro studies have shown inhibition of bladder cancer cell lines, cell cycle arrest, and induction of apoptosis by these isothiocyanates, in particular sulforaphane and erucin. Although not yet completely understood, many mechanisms of anticancer activity at the steps of cancer initiation, promotion, and progression have been attributed to these isothiocyanates. They target multiple pathways including the adaptive stress response, phase I/II enzyme modulation, pro-growth, pro-survival, pro-inflammatory signaling, angiogenesis, and even epigenetic modulation. Multiple in vivo studies have shown the bioavailability of isothiocyanates and their antitumoral effects. Although human studies are limited, they support oral bioavailability with reasonable plasma and urine concentrations achieved. Overall, both cell and animal studies support a potential role for isothiocyanates in bladder cancer prevention and treatment. Future studies are necessary to examine clinically relevant outcomes and define guidelines on ameliorating the bladder cancer burden.
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