Adolescent and mid-life diet: risk of colorectal cancer in the NIH-AARP Diet and Health Study.

BACKGROUND Colorectal cancer has a natural history of several decades; therefore, the diet consumed decades before diagnosis may aid in understanding this malignancy. OBJECTIVE The objective was to investigate diet during adolescence and 10 y before baseline (ages 40-61 y) in relation to colorectal cancer. DESIGN Participants in the NIH-AARP Diet and Health Study (n = 292,797) completed a 124-item food-frequency questionnaire (FFQ) about diet in the past 12 mo and two 37-item FFQs about diet at ages 12-13 y and 10 y previously. Cox regression was used to estimate multivariate HRs and 95% CIs for colon (n = 2794) and rectal (n = 979) cancers within quintiles of exposures. RESULTS Colon cancer risk was lower in the highest than in the lowest quintile of vitamin A (HR: 0.82; 95% CI: 0.72, 0.92) and vegetable (HR: 0.81, 0.70, 0.92) intakes during adolescence. Those in the highest intake category 10 y previously for calcium (HR: 0.83; 95% CI: 0.73, 0.94), vitamin A (HR: 0.81; 95% CI: 0.71, 0.92), vitamin C (HR: 0.83; 95% CI: 0.72, 0.95), fruit (HR: 0.84; 95% CI: 0.73, 0.97), and milk (HR: 0.78; 95% CI: 0.67, 0.90) had a lower risk of colon cancer, but a higher risk was observed for total fat (HR: 1.15; 95% CI: 1.01, 1.30), red meat (HR: 1.31; 95% CI: 1.12, 1.53), and processed meat (HR: 1.24; 95% CI: 1.06, 1.45). For rectal cancer, milk was inversely associated (HR: 0.75; 95% CI: 0.58, 0.96) with risk. CONCLUSION Adolescent and midlife diet may play a role in colorectal carcinogenesis.