Purpose: Previous studies suggest that diet may affect recurrence or survival rates in women who have been diagnosed with breast cancer. The purpose of this study was to examine the relationship between plasma carotenoid concentration, as a biomarker of vegetable and fruit intake, and risk for a new breast cancer event in a cohort of women with a history of early-stage breast cancer.
Methods: Participants were 1,551 women previously treated for breast cancer who were randomly assigned to the control arm of a diet intervention trial between March 1995 and November 2000. Outcome events were probed during semiannual interviews and verified by medical record review. During the period under study, 205 women had a recurrence or new primary breast cancer. Plasma carotenoid concentrations were measured in baseline blood samples. Hazard ratios (HR) and 95% CIs by quartiles of plasma carotenoids were computed, controlling for tumor stage, grade, and hormone receptor status; chemotherapy and tamoxifen therapy; clinical site; age at diagnosis; body mass index; and plasma cholesterol concentration.
Results: Women in the highest quartile of plasma total carotenoid concentration had significantly reduced risk for a new breast cancer event (HR, 0.57; 95% CI, 0.37 to 0.89), controlled for covariates influencing breast cancer prognosis.
Conclusion: Plasma carotenoids are a biologic marker of intake of vegetables and fruit, so this observation supports findings from previous studies that have linked increased vegetable and fruit intake with greater likelihood of recurrence-free survival in women who have been diagnosed with early-stage breast cancer.