Estrogens exposure as risk factor of breast cancer in premenopausal women all residing in the same metropolitan area. A case-control study in a cohort of 486 women

The aim of this study was to evaluate the weight of different risk factors (RF) in a cohort of premenopausal patients with breast cancer (BC), all residing in the same metropolitan area. Patients and Methods: Data regarding a series of 233 patients (cases), and 253 randomly age-matched healthy women (controls) were reviewed. Odds ratios (OR) estimated and the associated 95% confidence (CI) intervals were calculated. The chi-squared test and Student’s t-test were used to compare categorical variables and means of grouped data, respectively. Results: The results are reported in the Table. Age at menarche (12.1±2.3 vs. 12.8±1.8 years), age at first pregnancy (26.0±4.6 vs. 23.6±3.8 years), and months of breast feeding (9.3±7.2 vs. 12.1±7.1) significantly (p < 0.001) differ between cases and controls, while parity (1.4±1.5 vs. 1.4±0.9, p = 0.94), and months of oral contraceptives use (34.4±24.2 vs. 30.8±27.2, p = 0.21) did not. Conclusions: In this cohort of premenopausal patients, factors related to estrogens exposure (early age of menarche, late first pregnancy, and duration of oral contraceptive use) did not represent strong RF related to BC.