Adherence to the WCRF/AICR cancer prevention recommendations and mammographic density

Mammographic density (MD) is a known predictor of breast cancer risk and may be influenced by modifiable lifestyle factors. This study aimed to assess the association between adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations prior to diagnosis and MD in women diagnosed with breast cancer.

We analyzed data from 759 breast cancer patients recruited from eight Spanish hospitals enrolled in the case-case Breast Cancer & Density Association Study. Participants completed an epidemiological and a food frequency questionnaire. A standardized score was constructed to assess adherence to six WCRF/AICR recommendations. MD percentage was measured using the validated DM-Scan software on the digital mammogram of the contralateral, tumor-free, breast obtained prior to any treatment. Standardized prevalences and standardized prevalence ratios (SPRs) for four MD categories and for MD ≥ 50% across categories of adherence to the WCRF/AICR recommendations were estimated based on multinomial and binary multivariable logistic regression models.

Overall, adherence to the WCRF/AICR recommendations was not consistently associated with MD. However, the standardized prevalence of MD ≥ 50% was higher among women with high adherence compared to those with low adherence (SPR _{high vs. low} = 1.73; 95% CI = 1.03-2.91). This positive association was particularly evident with the physical activity recommendation (SPR _{fully met vs. no/partially met} = 1.51; 95% CI = 1.02-2.25).

Breast cancer participants with greater adherence to the WCRF/AICR recommendations prior to diagnosis, particularly to physical activity guidelines, showed higher percent MD at diagnosis. This association likely reflects lower absolute breast adiposity rather than a greater amount of fibroglandular tissue, and would therefore not imply an increased carcinogenic risk. These findings highlight the complex relationship between lifestyle behaviors and breast tissue composition.