Extra-tumoral breast tissue in breast cancer patients: Variations with steroid contraceptive use

Abstract

The association between oral contraceptive (OC) use and benign breast changes in extra-tumoral breast tissue was studied histologically in 1,503 breast cancer patients from The WHO Collaborative Study of Neoplasia and Steroid Contraceptives. The occurrence of ductal hyperplasia, ductal atypia, sclerosing adenosis, cysts, apocrine metaplasia, apocrine hyperplasia, apocrine atypia, adenosis, lobular atypia, duct ectasia, calcifications, inflammatory reaction, lactational metaplasia and a high epithelial-stromal ratio was graded semi-quantitatively. Prevalence odds ratio (POR) for each histologic variable was calculated by logistic regression analyses. Patients who had ever used OC had lower occurrence of ductal hyperplasia than never users (POR 0.72 (95% CI 0.52-0.99)). Current use and more than 8 years of use was also associated with a lower prevalence of ductal hyperplasia (POR 0.40 (0.20-0.81) and POR 0.33 (0.17-0.64), respectively). Age > 35 years at first use was associated with inc