ATBCs

ATBCs refers to theAlpha-Tocopherol Beta-Carotene Cancer Prevention Studies, a series of large randomized trials designed to test whether supplementation with vitamin E (alpha-tocopherol) and/or beta-carotene could prevent cancer and cardiovascular disease. The principal ATBC Cancer Prevention Study was conducted in Finland from the mid-1980s to the early 1990s. It enrolled about 29,000 male smokers aged 50 to 69 and used a 2-by-2 factorial design: alpha-tocopherol (50 mg daily), beta-carotene (20 mg daily), both, or placebo, with follow-up assessments for cancer and cardiovascular outcomes.

In trial results published in the 1990s, beta-carotene supplementation was associated with an increased incidence of lung cancer among smokers, with no overall protective effect against cancer or cardiovascular disease. Alpha-tocopherol, while not harmful, did not meaningfully reduce cancer or cardiovascular outcomes in the overall study population. Some secondary analyses suggested possible subgroup effects, but the primary conclusion did not support routine use of these supplements for cancer prevention in smokers.

Impact and legacy of the ATBC studies have been substantial. They contributed to a broader shift in guidelines regarding antioxidant supplementation, highlighting potential harm from beta-carotene in cigarette smokers and casting doubt on the general cancer-preventive benefits of vitamin E found in observational studies. The ATBC findings informed subsequent meta-analyses and trial designs, reinforcing the view that supplementation with beta-carotene or vitamin E is not broadly protective against cancer or cardiovascular disease.