shows the baseline characteristics of participants according to quintiles of adolescent total fat intake in adolescence. The mean age of participants in 1998 was 44 years (range 34 – 53). The reported intake of total dietary fat ranged from 28–188 grams per day (mean 124 grams per day, representing approximately 40% of total calories from fat. Compared to women in the lowest quintile of adolescent dietary fat intake, those in the highest quintile were more likely to be smokers and drink alcohol in adulthood.
Characteristics of participants at baseline in adulthood by 1998 and in adolescence by quintiles of energy-adjusted adolescent total fat intake
During the average 7.8 years of follow-up, ranging from the return of the HS-FFQ in 1998 to June 2005, 455 premenopausal women were diagnosed with invasive breast cancer. The risk of breast cancer was higher among women who consumed more fat during adolescence. The multivariate relative risk was 1.35 (95% CI: 1.00, 1.81, Ptrend
=0.05) comparing the highest quintile to the lowest however no clear dose-response relationship was noted across quintiles of total fat (). Of note, total fat intake in adulthood was inversely related to breast cancer in this sub-group of women. Adjustment for adult fat intake did not appreciably change the fat-breast cancer association, which remained statistically significant (RR=1.47, 95% CI: 1.08, 2.01, Ptrend
=0.02). Our results did not change appreciably when using different models for energy adjustment including the standard model, nutrient density model or residual models(19
) (data not shown). Concurrent adjustment for adolescent red meat intake, attenuated this association to RR=1.24 (95% CI: 0.89, 1.72, Ptrend
=0.25). Red meat intake during adolescence was associated with breast cancer in this group of women (RR=1.34, 95% CI: 0.94, 1.89 comparing highest to lowest quintile)(20
). The main food item contributing to total fat intake in this population was milk (8%) followed by main dishes of beef (7%), pork (5%), chicken or turkey (4%) and processed meat (4%).
Energy and multivariable-adjusted hazard ratios and 95% confidence intervals for invasive breast cancer risk in association with total and type of fat intake during adolescence among 39,268 premenopausal women in the Nurses Health Study II
Polyunsaturated fat showed a borderline significant trend towards a positive association with breast cancer, (RR=1.29, 95% CI: 0.96, 1.73, ptrend=0.07). Individual types of fat including saturated, monounsaturated and trans fat were not significant predictors of premenopausal breast cancer in this study. Similarly, subdividing fat intake according to animal or vegetable origin did not show a significant association between either of these groups and breast cancer.
The associations between total carbohydrate and quality of carbohydrate are shown in . Comparing the highest quintile of intake to the lowest, there was an inverse association between breast cancer and total carbohydrate (RR=0.85, 95% CI: 0.63, 1.14) and glycemic load (RR=0.89, 95% CI: 0.66, 1.20) although these trends did not reach statistical significance. Total carbohydrate was highly inversely correlated with dietary fat in this group of women (R=−0.89). Fiber was not significantly associated with breast cancer risk (RR=0.96, 95% CI: 0.80, 1.14)).
Energy and multivariable-adjusted hazard ratios and 95% confidence intervals for invasive breast cancer risk in association with total carbohydrate and carbohydrate quality among 39,268 premenopausal women in the Nurses Health Study II
Of the breast cancer cases with available pathology reports, 268 were Estrogen receptor (ER) and Progesterone receptor (PR) positive and 72 were ER/PR negative. presents the association between total and subtypes of fat and breast cancer according to hormone receptor status. When total fat intake was modeled as a continuous variable, the RR of breast cancer was 1.07 (95% CI: 0.99, 1.15) for each additional 100 calories from fat. When we subdivided breast cancers according hormone receptor status, associations between total dietary fat were stronger among ER/PR negative tumors (RR=1.27, 95% CI: 1.04, 1.56, P=0.02) than for ER/PR positive tumors (RR=1.04, 95% CI: 0.94, 1.15, P=0.43) per 100 calories. Saturated fat was significantly related to ER/PR negative tumors (RR=1.57, 95% CI: 1.11, 2.23, P=0.01) but not to ER/PR positive tumors (RR=0.95, 95% CI: 0.79, 1.13, P=0.55). No overall association between total milk or total dairy intake were observed, although a non-significant inverse trend between breast cancer and low-fat milk and low fat dairy was noted ().
Multivariable-adjusted hazard ratios and 95% confidence intervals for invasive breast cancer risk in association with fat and carbohydrate intake according to estrogen and progesterone receptor status of tumors.
Milk and dairy intake in adolescence and risk of breast cancer