An Adolescent and Early Adulthood Dietary Pattern Associated with Inflammation and the Incidence of Breast Cancer.

Adolescence is a highly susceptible period for mammary carcinogenesis, but few prospective studies have examined the role of adolescent diet in breast cancer risk. Reduced rank regression has previously been used to identify a dietary pattern associated with markers of inflammation (C-reactive protein, IL6, and TNFα receptor 2). We investigated whether an adolescent and early adulthood inflammatory dietary pattern was associated with breast cancer among 45,204 women in the Nurses' Health Study II using reduced rank regression. Participants completed a food frequency questionnaire in 1998 about their high school diet (HS-FFQ) and a FFQ in 1991 when they were ages 27-44 years. Among women who completed the HS-FFQ, 1,477 cases of breast cancer were diagnosed during 22 years of follow-up. An adolescent and early adulthood dietary pattern characterized by inflammation was associated with an increased incidence of premenopausal but not postmenopausal breast cancer. Women in the fifth quintile of the inflammatory pattern score had multivariable adjusted HRs for premenopausal breast cancer of 1.35 for adolescent diet [95% confidence interval (95% CI), 1.06-1.73; Ptrend = 0.002] and 1.41 for early adulthood diet (95% CI, 1.11-1.78; Ptrend = 0.006) compared with women in the first quintile. The corresponding RRs for postmenopausal breast cancer were 0.84 (95% CI, 0.60-1.17) for adolescent and 0.76 (95% CI, 0.54-1.06) for adult intake. Overall, our findings support the notion that an adolescent and early adulthood diet characterized by high intake of sugar-sweetened and diet soft drinks, refined grains, red and processed meat, and margarine, and low intake of green leafy vegetables, cruciferous vegetables, and coffee may increase the incidence of premenopausal breast cancer. Cancer Res; 77(5); 1179-87. ©2017 AACR. ©2017 American Association for Cancer Research.