Abstract P4-13-03: Hormone replacement therapy, is there an increased risk of in situ breast cancer ? data from a french cohort

Abstract

Abstract Background: Use of hormone replacement therapy (HRT) has been associated with an increased risk of breast cancer. Few studies focus on correlation between HRT and in situ breast cancer A large cohort study, the Million Women Study (Reeves GK et al. Lancet Oncol. 2006) have shown that the use of HRT has been associated with an increased incidence of in situ breast cancer (RR = 1, 55, IC=1, 4–1,72, p = 0,03). Purpose: We investigated the association between HRT use and duration and in situ breast cancer incidence from a data base of infraclinic breast lesions. Materials & Methods: From 2007 to 2011, 2708 patients (pts) with a non palpable breast lesion were referred to our breast disease unit for exploration (Saint Louis Hospital, Paris). Radiological abnormalities were screened by mammography and/or breast ultrasound, and/or MRI. Out of 2708 pts, 1668 had a biopsy. All biopsies were seen by an anatomopathologist dedicated to breast. Here, we focus on the 1017 postmenopausal women (61%). Results: Biopsies revaled invasive breast cancers in 222 pts (22%), in situ breast cancers in 164 pts (16%) [10 lobular in situ carcinoma and 154 ductal in situ carcinoma], high risk breast lesions in 103 pts (10%) and benign breast lesions in 528 patients (52%). Characteristics of the 164 patients with in situ breast cancer: median age 62 [IQR: 57 to 68], at least one pregnancy (mean number of pregnancies per woman, 1.6) 75,6%, family history of breast cancer:30,2%. Among these 164 patients, 42.6 % had used an oral contraceptive and 53% of them a HRT, with a mean duration of use of 7 years. The HRT use was not significantly associated with in situ breast cancer (p = 0.66) as well as the duration of HRT. Discussion: In this study of postmenopausal women, HRT use, whatever is the duration, was not associated with in situ breast cancer. Although a lack of statistical power may be invoked to explain these results, these findings suggest that the type of the HRT could be important to explain the difference between our study and the Million Women Study. In our study, the HRT used is in the majority of the pts, percutaneous oestrogens and natural progesterone as it is the most commun HRT used in France (Fournier A, Int J Cancer. 2005) during this period of time. Use and type of HRT are different in USA where conjugated estrogens and medroxy progestogerone acetate were commonly used. Conclusion: We therefore encourage further studies to better appreciate the links between type of HRTs and in situ breast cancer. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-13-03.