No effect of 325 mg of aspirin every other day over a 5 year period on the incidence of colorectal cancer.
The Physicians Health Study II is a randomized, double-blind trial testing the long-term effects of common multivitamins in the prevention of chronic disease.
In the above study 14,641 male US physicians enrolled in a common vitamin study beginning in 1997 with treatment and follow-up through 2011: it was an associated reduction in total cancers among men with baseline history of cancer, but did not differ significantly among men initially without cancer.
Supplements of 500 mg/day vitamin C plus 400 IU vitamin E every other day for a mean follow-up period of 8 years failed to reduce the risk cancer compared with placebo in middle-aged and older men participating in the Physicians’ Health Study II .