Background: Oral contraception (OC) is one of the most widely used means for birth control in the world. In several studies, OC has been associated with a slightly increased risk of breast cancer in current user, and with a decreased risk of benign disease. Little is known about atypical high risk lesions. Our goal was to investigate whether OC use was a risk factor or a protective factor for benign, high risk or malignant breast lesions. Material and methods : From 2001 to 2007, all non-palpable breast lesions referred to biopsy or cytology in Saint Louis hospital were prospectively registered. Demographic and clinical data including oral contraceptive pill use extent were reported. We defined benign lesions (fibroadenoma, blunt duct adenosis, fibrocystic changes, epithelial hyperplasia, others), high risk lesions (atypical ductal hyperplasia, atypical lobular hyperplasia, lobular carcinoma in situ and malignant lesions (ductal carcinoma in situ, invasive ductal or lobular carcinoma). The aim was to analyse the correlation between the duration of OC use and the occurrence of the breast disease classified by histology groups. Patients with previous history of benign breast disease or malignancy were excluded.

Results: The analysis was performed on 1329 breast lesions. The breakdown of the lesions were as follows: 819 benign lesions (fibroadenoma n=155, blunt duct adenosis n=169, fibrocystic disease n=194, epithelial hyperplasia n=132, others n=170), 104 high risk lesions (atypical ductal hyperplasia n=54, atypical lobular hyperplasia n=29, lobular carcinoma in situ n=21), and 406 malignant lesions (ductal carcinoma in situ n=158, invasive ductal or lobular carcinoma n=248). The duration of oral contraception use was not significantly associated with the occurrence of benign, high risk or malignant breast disease. When focusing on benign lesion subtypes, no association was observed either. Older age was significantly correlated to the occurrence of atypia or carcinoma. Significant difference existed in the median age of apparition 55 y.o and 57 y.o respectively, versus 53 y.o for benign lesion (p< 0,0001), as well as menopausal status at diagnosis (57.7% and 68.3%, respectively, versus 53% for benign lesion) (p< 0,0001).

Conclusion: In this cross sectional retrospective study, the duration of OC use was not associated with differential occurrence of benign, high risk and malignant breast lesion. Although a lack of statistical power may be invoked to explain the results, we are called to believe that the magnitude of an effect of OC use is small, if ever it exists.

Results [Table 1]

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-09-06.