ERDP score was significantly, albeit weakly, associated with unconjugated E2 (r, .27; P < .0001) and the 2/16 ratio (r, -0.16; P < .0001). Foods most strongly associated with unconjugated E2 were non-whole/refined grains, cheese, yogurt, and franks/luncheon meats; non-whole/refined grains and cheese were strongly associated with the 2/16 ratio.
Higher ERDP scores were significantly associated with women who developed breast cancer during study follow-up compared with women not diagnosed with the disease (0.037 vs -0.009, respectively; P = .006).
Increasing ERDP quartiles were associated with an increased risk of postmenopausal breast cancer. Women in the highest quartile of ERDP demonstrated the greatest risk of postmenopausal total breast cancer (hazard ratio [HR], 0.14; 95% CI, 0.98-1.32) and invasive breast cancer (HR, 1.20; 95% CI, 1.02-1.42). The association remained for ER-positive disease, but not ER-negative disease.
“These results contribute to the greater body of literature and suggest that diet may influence breast cancer risk through an effect on estrogen, although more research is needed,” Dr Guinter said.
Elisa Bandera, MD, PhD, of the Rutgers Cancer Institute in New Brunswick, New Jersey, who was not affiliated with the study, agreed, telling Cancer Therapy Advisor that although “this is an interesting paper,” the “findings will need to be replicated and the ERDP validated in other populations.”
Given this, she said that at this time “this ERDP cannot be translated to the clinic.” Both Drs Guinter and Bandera recommended that clinicians direct patients to the dietary guidelines for cancer prevention published by the American Institute for Cancer Research (AICR) or the ACS.
According to Dr Bandera, “the dietary pattern identified as low estrogenic in this study is actually very similar to the one recommended by the AICR/ACS — high in fruit and vegetables and whole grains, low in processed food which are high in fat and sugars, and low in red meat and processed meat.” She noted that these recommendations are based on strong scientific evidence from many different cohort studies.
Dr Guintar noted that the authors are publishing a study that combines the ERDP with other lifestyle factors associated with estrogen to determine if an overall lifestyle can modify breast cancer risk, which is also similar to the AICR/ACS recommendations.
“Findings indicated that women who consume a low estrogenic diet, are physically active, don’t drink, and maintain a healthy body weight have a lower risk of postmenopausal breast cancer,” he said.
- Guinter MA, McLain AC, Merchant AT, Sandler DP, Steck SE. A dietary pattern based on estrogen metabolism is associated with breast cancer risk in a prospective cohort of postmenopausal women. Int J Cancer. 2018 Mar 25. doi: 10.1002/ijc.31387 [Epub ahead of print]