Inflammation-associated dietary patterns and mammographic density

From th Harris Group, Division of Public Health Sciences

The relationship between diet in adulthood and risk of breast cancer has been extensively studied. There is strong evidence that experiences prior to first birth play a role in shaping breast cancer risk. Mammary tissue develops during adolescence, but terminal structures of the mammary glands do not differentiate until the first pregnancy. Therefore, adolescence and early adulthood are crucial times for risk factors that contribute to the development of breast cancer.  Previous studies focused on specific food groups to evaluate adult diet and mammographic density.  Dr. Nichole Garzia, the first author of a new publication from the Harris group in the Public Health Sciences Division, stated, “Few studies have evaluated the role of early life diet on premenopausal mammographic density, and to our knowledge, our study is the first to evaluate this association using dietary patterns. In other words, we did not focus on a single food item or nutrient, we focused on overall diet in terms of inflammation.”

Hence, the objective of the study was to examine the association between adolescent and early adulthood dietary patterns and premenopausal mammographic density. The Harris Group also evaluated whether the associations between these dietary patterns differed by body mass index and other risk factors for breast cancer associated with mammographic density.  The two dietary patterns examined in the study were the a pro-inflammatory dietary pattern and the Alternative Healthy Eating Index (anti-inflammatory dietary pattern).  This study was published in Breast Cancer Research.

The study population for this analysis was from the Nurses Health Study II (NHSII), an ongoing prospective cohort that assess lifestyle and other factors, and medical history biennially via questionnaires.  Screening mammograms were collected from 1996 to 1999. Early adulthood diet was assessed in 1991 when participants completed an food frequency questionnaire (FFQ). Adolescent diet was assessed in 1998, when participants completed in a FFQ that asked about the foods they consumed during high school (HS-FFQ). The pro-inflammatory dietary pattern is was created based on foods that correlated with inflammatory biomarkers. The Alternative Healthy Eating Index (anti-inflammatory) was developed based on foods consistently associated with chronic illnesses. Scoring is based on 11 components: fruits, vegetables, whole grains, sugar-sweetened beverages, nuts and legumes, red and processed meat, trans fat, long chain fats, polyunsaturated fat, sodium, and alcohol. Mammographic density was assessed from digitized film mammograms.  The final analytic sample include 677 premenopausal, cancer free women.  General linear models were used to evaluate the associations.

In the age-adjusted analyses, The Harris Group found that as adolescent pro-inflammatory diet pattern increased, percent of mammographic density decreased (ptrend=0.005) and non-dense area increased (ptrend= <0.0001).  In the multivariable analyses, no associations were observed for early adulthood dietary pattern and mammographic density.  Among individual covariates, the effect estimates greatly reduced with the adjustment for BMI at the time of mammogram. In addition, no significant associations between dietary pattern and percent mammographic density was observed in each BMI strata (< 25 vs. ≥ 25). 

In conclusion, after adjustment for covariates including BMI, the Harris Group did not find an association between the pro-inflammatory or anti-inflammatory diet during adolescence or early adulthood and premenopausal mammographic density. Dr. Garzia concluded, “We did not observe any significant associations in the current study, but I believe this is just the start. We need more research in this area of early life dietary exposure and breast cancer risk factors, because characterizing the appropriate exposure window is critical for epidemiology. Mammographic density is a risk factor that has a significant impact on future breast cancer risk, so increased knowledge of this risk factor can help improve breast cancer prevention.”

This work was supported by the Breast Cancer Research Foundation. The Nurses’ Health Study II is supported by the National Institutes of Health U01-CA176726.

Fred Hutch/UW Cancer Consortium members Holly R. Harris and Thomas Kensler contributed to this work.

Garzia NA, Cushing-Haugen K, Kensler TW, Tamimi RM, Harris HR. Adolescent and early adulthood inflammation-associated dietary patterns in relation to premenopausal mammographic density. Breast Cancer Research. 2021 Dec;23(1):1-1. DOI: 10.1186/s13058-021-01449-0