Lower breast cancer risk among women following lifestyle recommendations: a case-control study in Spain
METHODS: Epi-GEICAM is a nation-wide case-control study, 1019 cases from 23 hospitals were matched to 1019 controls by age and municipality of residence. The cases were sub classified by tumor subtype: 1) Estrogen Receptor(ER)+ or Progesterone Receptor(PR)+ with Human Epidermal Growth Factor Receptor 2(HER2)-; 2) HER2+; and 3) ER-,PR-&HER2- tumors. We constructed a score (0-9) based on 9 of the 10 WCRF/ AICR recommendations. The score was grouped in 4 categories (0 to <4, 4 to <5, 5 to <6 and ≥6) and its association with BC risk was evaluated using conditional logistic regression models adjusted by total calorie intake, smoking habit, age at first delivery, education, history of breast problems, family history of BC and menopausal status. Multinomial logistic regression models were used to evaluate the association of the WCRF/AICR score with each of the intrinsic BC subtypes. These models were adjusted by age, hospital, and the same set of potential confounders described above.
RESULTS: The women with higher score showed a decreased risk of BC (OR[6-9]vs[0-4] =0.51; 95%CI=0.36-0.73 and ORunit-increase=0.82; 95%CI =0.74-0.91; p-trend<0.001). This preventive effect was slightly more pronounced in postmenopausal women (OR[6-9]vs[0-4] =0.43; 95%CI=0.26-0.70 and ORunit-increase=0.81; 95%CI=0.71-0.93, p-trend=0.001) and in women with ER+/PR+&HER2- tumors (OR[6-9]vs[0-4] =0.43; 95%CI =0.30-0.62 and ORunit-increase=0.78; 95%CI=0.70-0.87; p-trend<0.001). However, none of the differences in the magnitude of risk by menopausal status and intrinsic tumor subtypes was statistically significant.
CONCLUSIONS: Adherence to the WCRF/AICR recommendations for cancer prevention might reduce breast cancer risk in both pre and postmenopausal women and all cancer subtypes.