Colorectal cancers epidemiological findings

Carotenoids and urino-digestive cancers — On the whole, findings from epidemiological studies did not demonstrate a protective role of carotenoids against colorectal, gastric, and bladder cancers. Indeed, most prospective and case-control studies of colorectal cancer showed no association with dietary intake or plasma level of most carotenoids. - Only lycopene and lutein were shown to be protective against colorectal cancer. Otherwise, findings from the ATBC study s showed no effect of P-carotene supplementation on colorectal cancer. 

A chronic inhalation study found no evidence of carcinogenic activity in rats exposed at concentrations of 600 ppm or 12 00 ppm for 2 years, or in mice exposed at 120, 600, or 1200 ppm for the same duration.Epidemiological findings of various cancer (stomach, lung, and colorectal) increases with toluene exposure are not strong enough to conclude an association because of multiple exposure circumstances and weak consistency of findings."... 

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