Abstract 855: History of oral contraceptive use in breast cancer patients and risk for early breast cancer events

Abstract

Abstract Whether previous oral contraceptive (OC) use impacts on prognosis women who subsequently develops breast cancer is unclear. The aim was to study history of OC use in relation to breast cancer events in a prospective population-based cohort. Between 2002 and 2011, primary breast cancer patients without preoperative treatment were enrolled in Lund, Sweden and followed until December 2012. Tumor characteristics, clinical data, and date of death were obtained from pathology reports, patient charts, and population registries. History of OC use was obtained from preoperative questionnaires. Among the 948 patients with invasive cancer and no metastasis detected on the postoperative screen, 74% had ever used OCs. Patients were followed for up to nine years and 100 breast cancer events were recorded. Ever OC users had significantly smaller tumors than patients who never used OCs (Ptrend = 0.013). However, there was a significantly higher frequency of grade III tumors in patients with OCs use before age 20 (Ptrend = 0.013), compared to patients with later start or never use. Ever OC use was not associated with prognosis, irrespective of duration. However, any OC use before age 20 was associated with a 3-fold increased risk for breast cancer events in patients younger than 50 years at diagnosis (adjusted HR 3.26: 95% CI 1.06-10.01) adjusted for age, tumor size, axillary lymph node involvement, histological grade, estrogen receptor status, and body mass index, but not in patients 50 years or older at diagnosis (Pinteraction = 0.009). In conclusion, these findings warrant confirmation in an independent cohort. If confirmed, history of OC use may yield prognostic information in addition to currently used criteria. Citation Format: Louise Huzell, Mia Persson, Maria Simonsson, Andrea Markkula, Christian Ingvar, Carsten Rose, Helena C. Jernström. History of oral contraceptive use in breast cancer patients and risk for early breast cancer events. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 855. doi:10.1158/1538-7445.AM2015-855