title: An unusual request to a willing study population.
mesh_terms: D000368:Aged; D001241:Aspirin; D002318:Cardiovascular Diseases / Q000517:prevention & control; D002338:Carotenoids; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000517:prevention & control; D011897:Random Allocation; D019207:beta Carotene
chemical_list: D019207:beta Carotene; D002338:Carotenoids; D001241:Aspirin