Is uterine serous carcinoma a part of hereditary breast cancer syndrome

Supplementary abstract 5887

Background: Whilst the association between breast cancer and uterine serous carcinoma (USC) is attributed to tamoxifen treatment, few studies have reported that this increased risk is independent of tamoxifen. Methods: To further investigate the relationship between breast cancer and USC, we retrospectively studied 216 patients from 5 hospital trusts in Birmingham, UK who were diagnosed with USC between 1993 and 2012. We collected personal history of cancer in these cases before or after USC diagnosis. In addition FIGO staging, clinical and survival data were collected from our local cancer registry and patients’ clinical records. Results: In this case series, 56 patients (25.9%) had personal history of at least one cancer before and 18 patients (8.3%) had history of at least one cancer after the diagnosis of USC. Within the group of patients with the history of cancer before the USC, 38 patients (68%, 17.5% of all cases) had personal history of breast cancer prior to the development of USC, higher than the UK expected age standardised relative incidence of breast cancer (350 in 100,000, CRUK 2006-2008). Although 27/38 cases (71%) had endocrine treatment for their primary breast cancer, 11/38 patients (29%) did not have any tamoxifen treatment due to hormone receptor negative breast cancer. Additionally the median age of breast cancer diagnosis for the hormone receptor negative group was significantly lower than those patients who had hormonal treatment for their breast cancer (56 vs. 64 years, p :0.036) compatible with the younger age at diagnosis expected of the familial (BRCA mutated) or triple negative breast cancer. Of 18 patients with a second cancer after diagnosis of USC, 6 patients (33%) were diagnosed with breast/ovarian cancer. This group also had no treatment with tamoxifen. Conclusions: Lack of exposure to tamoxifen and younger age at diagnosis in this subgroup suggest that other factors such as a common underlying genetic predisposition may be responsible for the development of both malignancies. We propose that at least a subgroup of USC may be a part of hereditary breast cancer syndrome. This may have implications in prevention (prophylactic hysterectomy) or trials of targeted treatments (PARP inhibitors) for a subgroup of USC patients.