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Postdiagnostic Dietary Glycemic Index, Glycemic Load, Dietary Insulin Index, and Insulin Load and Breast Cancer Survival.

ABSTRACT:

Background

We investigated the associations of postdiagnostic dietary glycemic index (GI), glycemic load (GL), insulin index (II), and insulin load (IL) with breast cancer-specific and all-cause mortality.

Methods

Among 8,932 women with stage I-III breast cancer identified in the Nurses' Health Study (NHS; 1980-2010) and NHSII (1991-2011), we prospectively evaluated the associations between postdiagnostic GI, GL, II, and IL, and breast cancer-specific and all-cause mortality. Participants completed a validated food frequency questionnaire every 4 years after diagnosis.

Results

During follow-up by 2014 in the NHS and 2015 in the NHSII, 2,523 deaths, including 1,071 from breast cancer, were documented. Higher postdiagnostic GL was associated with higher risk of both breast cancer-specific mortality [HR_Q5vsQ1 = 1.33; 95% confidence interval (CI) = 1.09-1.63; P _trend = 0.008] and all-cause mortality (HR_Q5vsQ1 = 1.26; 95% CI = 1.10-1.45; P _trend = 0.0006). Higher all-cause mortality was also observed with higher postdiagnostic GI (HR_Q5vsQ1 = 1.23; 95% CI = 1.08-1.40; P _trend = 0.001), II (HR_Q5vsQ1 = 1.20; 95% CI = 1.04-1.38; P _trend = 0.005), and IL (HR_Q5vsQ1 = 1.23; 95% CI = 1.07-1.42; P _trend = 0.0003). The associations were not modified by insulin receptor or estrogen receptor status of the tumor, or body mass index.

Conclusions

We found that higher dietary GL, reflecting postprandial glucose response, after a breast cancer diagnosis was associated with higher risk of breast cancer-specific mortality. Higher dietary GI, GL, II, and IL after a breast cancer diagnosis were associated with higher risk of death from any cause.

Impact

These results suggest that carbohydrate quantity and quality may be important in breast cancer prognosis.See related commentary by McTiernan, p. 252.

SUBMITTER: Farvid MS

PROVIDER: S-EPMC7984717 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:A few studies have evaluated the association between diet and mammographic breast density (MBD) and results are inconsistent. MBD, a well-recognized risk factor for breast cancer, has been proposed as a marker of cumulative exposure to hormones and growth factors. Diets with a high glycemic index (GI) or glycemic load (GL) may increase breast cancer risk, via an effect on the insulin-like growth factor axis. We have investigated the association between carbohydrate intake, GI, GL and MBD in a prospective study. We identified a large series of women, in the frame of the EPIC-Florence cohort, with a mammogram taken five years after enrolment, when detailed information on dietary and lifestyle habits and anthropometric measurements had been collected. Mammograms have been retrieved (1,668, 83%) and MBD assessed according to Wolfe's classification. We compared women with high MBD (P2+DY Wolfe's categories) with those with low MBD (N1+P1) through logistic models adjusted for age, education, body mass index, menopause, number of children, breast feeding, physical activity, non-alcohol energy, fibers, saturated fat and alcohol. A direct association between GL and high MBD emerged in the highest quintile of intake in comparison with the lowest quintile (OR = 1.73, 95%CI 1.13-2.67, p for trend = 0.048) while no association with glycemic index was evident. These results were confirmed after exclusion of women reporting to be on a diet or affected with diabetes, and when Hormone Replacement Therapy at the date of mammographic examination used to assess MBD was considered. The effect was particularly evident among leaner women, although no interaction was found. A positive association was suggested for increasing simple sugar and total carbohydrates intakes limited to the highest quintiles. In this Italian population we observed an association between glycemic load, total and rapidly absorbed carbohydrates and high MBD. These novel results warrant further investigations.