The current study examined the associations between antioxidant use after breast cancer (BC) diagnosis and BC outcomes in the Life After Cancer Epidemiology (LACE) cohort. The cohort included 2264 women who were diagnosed with early stage primary BC from 1997 to 2000 who enrolled, on average, two years post-diagnosis. Antioxidant supplement use after diagnosis was reported by 81% of women. Among antioxidant users, frequent use of vitamin C and vitamin E was associated with a decreased risk of BC recurrence (vitamin C: HR 0.73; 95% CI 0.55-0.97; vitamin E: HR 0.71; 95% CI 0.54-0.94) and vitamin E use was associated with a decreased risk of all-cause mortality (HR 0.76; 95% CI 0.58-1.00). Conversely, frequent use of combination carotenoids was associated with increased risk of death from BC (HR 2.07; 95% CI 1.21-3.56) and all-cause mortality (HR 1.75; 95% CI 1.13-2.71). Therefore, the effects of antioxidant supplement use after diagnosis likely differ by type of antioxidant; frequent use of vitamin C and vitamin E in the period after BC diagnosis may decrease the likelihood of recurrence, whereas frequent use of combination carotenoids may increase mortality. Cancer. 2011 Sep 27. PMID: 21953120.
