Dr. Yuesheng Zhang, PhD, lead researcher and professor of oncology at Roswell Park Cancer Institute, said the study carried out in an animal model provides strong evidence that eating vegetables is beneficial in bladder cancer prevention.
The team led by Zhang tested the ability of the concentrate to prevent bladder tumours in five groups of rats.
The first was a control group, while the second group was given only the broccoli extract to test for safety. The remaining three groups were given a chemical, N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in drinking water, which induces bladder cancer.
Out of the three two were given the broccoli extract in diet, two weeks before the carcinogenic chemical was delivered.
The findings revealed that the control group and the group given only the extract developed no tumours, and there was no toxicity from the extract in the rats.
They found that nearly 96 per cent of animals given only BBN developed an average of almost two tumours each of varying sizes.
And about 74 per cent of animals given a low dose of the extract developed cancer, and the number of tumours per rat was 1.39. The group given the high dose of extract had even fewer tumours.
Though animals that had the most protection against development of bladder cancer were given high doses of the extract, Zhang said humans at increased risk for this cancer likely do not need to eat huge amounts of broccoli sprouts in order to derive protective benefits.
The report will appear in the March 1 issue of Cancer Research , a journal of the American Association for Cancer Research.