Association Between Plant-Based Diet Index and Breast Cancer Risk Stratified by Menopausal and Hormone Receptor Status: A Case-Control Study Among Korean Women.

BACKGROUND

This study aims to examine the association between a plant-based diet index (PDI) and the risk of breast cancer in Korean women. Additionally, we aim to assess whether the associations differ by menopausal status and in estrogen receptor (ER) and progesterone receptor (PR) status.

METHODS

In this case-control study, we included 395 breast cancer patients and 395 age-matched controls from the National Cancer Center Hospital. The overall PDI, healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI) were calculated based on dietary intake assessed using a 106-item semi-quantitative food frequency questionnaire. Logistic regression was used to estimate odds ratios and 95% confidence intervals for the association between plant-based diets and breast cancer, adjusting for potential confounders.

RESULTS

We found that PDI was inversely associated with breast cancer, while uPDI was positively associated. However, hPDI was not significantly associated with breast cancer after multivariable adjustment. In analyses stratified by menopausal status, PDI showed an inverse association with breast cancer in premenopausal women, while uPDI was positively associated with breast cancer in both pre- and postmenopausal women. Additionally, when stratified by ER and PR status, we observed that both PDI and uPDI showed stronger associations in the ER+/PR+ group, whereas hPDI remained non-significant in both the ER+/PR+ and ER-/PR- groups.

CONCLUSION

A higher PDI was associated with lower odds of breast cancer, supporting the recommendation to increase plant-based food intake and reduce animal food intake as part of dietary guidance for breast cancer prevention.