Isothiocyanates Found in Cruciferous Vegetables May Protect Against the Genesis of Bladder Cancer

24/05/07 Isothiocyanates (ITC) are compounds found in cruciferous vegetables such as broccoli, cauliflower, kale, turnips, collards, Brussels sprouts, cabbage, radish, turnip and watercress.

They exert their anti-oxidant effect via down regulation of cytochrome p450 enzyme levels and induce apoptosis by activating Phase II detoxifying enzymes. Experimental data has suggested that these compounds may protect against the genesis of bladder cancer.

In the May 15th issue of the International Journal of Cancer, Zhao and colleagues from the Departments of Epidemiology and Urology at the M.D. Anderson Cancer Center report on an epidemiological study evaluating the relationship between ITC intake and bladder cancer risk.

The cohort consisted of 697 patients with newly diagnosed bladder cancer and 708 healthy controls matched by age, sex, and race. Dietary questionnaires were available for all patients. The dietary intake of ITCs was compared with bladder cancer risk and with the expression of genetic polymorphisms for the arylamine N-acetyltransferases 2 (NAT) and glutathione S-transferase genes.

Median ITC intake per day was significantly lower in bladder cancer patients than in controls (0.23 vs. 0.33, p < 0.001). High ITC intake was associated with 29% lower risk of bladder cancer (odds ratio = 0.71, 95% CI 0.57 to 0.89). This anti-cancer effect was seen more commonly in men, in patients age 64 or older, and in smokers. NAT2 slow acetylators exhibited an increased risk of bladder cancer in Caucasians compared with rapid acetylators (OR = 1.31, 95% CI 1.02 to 1.69). The decrease in bladder cancer risk associated with ITC intake was not associated to NAT2, GSTM1, or GSTT1 genotype expression.

This well-conducted study for the first time demonstrates that consumption of cruciferous vegetables with a high content of isothiocyanates such as broccoli, cauliflower, kale, turnips, collards, Brussels sprouts, cabbage, radish, turnip and watercress may offer a protective advantage against bladder cancer. Whether increasing ITC intake in bladder cancer patients improves treatment response and prevents recurrence remains to be studied.