Abstract P4-12-13: Experience of pre-operative genetic testing on surgical decision making in newly diagnosed breast cancer patients

Introduction: BRCA 1 and 2 testing has been widely incorporated into clinical care for women at risk for hereditary breast cancer. Knowledge of BRCA mutation status prior to surgery may influence decision regarding type of surgery. This study analyzes the experience with pre-operative BRCA mutation testing in patients with suspected hereditary predisposition to breast cancer. Methodology: Records of 150 patients referred to Cancer Genetics between November 01, 2013 and April 30, 2014 for pre-operative genetic testing were analyzed. This cohort consisted of patients with newly diagnosed breast cancer who met current genetic testing criteria. Patients were excluded if their surgical records were not available or they had not yet completed surgery. A total of 80 patients who completed genetic evaluation and definitive surgery were evaluated. Data on demographic characteristics, tumor pathology, BRCA mutation status and surgical management was collected on all evaluable patients. Results: Records of 80 patients who underwent pre-operative genetic testing for hereditary breast cancer risk were evaluated. The median age at diagnosis was 51.5 years. Median time from biopsy to initiation of genetics referral was 10 days. From that point, the median time to cancer genetics appointment was 3 days. Median time from initial genetics visit to definitive surgery was 24 days. 7 (9%) patients underwent surgery within 10 days of the genetics appointment, and prior to receiving the results of the genetic tests. Of the 80 patients, 5 (6%) tested positive for a BRCA mutation, 3(4%) had a BRCA variant of unknown significance(VUS), and the rest tested negative. 4 of the 5 BRCA mutation carriers underwent bilateral mastectomy, as did 2 of the 3 patients with a BRCA VUS. Of the 72 BRCA -ve patients, 22 (30%) underwent bilateral mastectomies, 42 (58%) underwent partial mastectomy, 7 (10%) patients underwent unilateral mastectomy, and 1 underwent bilateral partial mastectomy. There was no significant difference on univariate analysis in the age, histopathology (grade, receptor status, lymph node status and margins) in the patients who underwent bilateral mastectomy and those who underwent breast conservation. Mean tumor size was 24.5 mm in the bilateral mastectomy group, compared to 15.8 mm in the unilateral mastectomy group(p=NS). The bilateral mastectomy group had a greater number of close relatives with breast cancer reflecting a more significant family history. Conclusions: This study demonstrates the feasibility and successful implementation of preoperative genetic testing in newly diagnosed breast cancer patients. The majority of mutation carriers underwent bilateral mastectomies as did a significant proportion of BRCA -ve patients. Larger tumor size and a more significant family history of breast cancer appeared to be associated with the decision to pursue bilateral mastectomy. Further studies are needed to better characterize the impact of preoperative genetic testing in newly diagnosed breast cancer patients. Citation Format: Siddhartha Yadav, Otavio Pereira-Rodrigues, Lindsay Dohany, Heidi Dreyfuss, Jennifer Fulbright, Ashley Reeves, Dana Zakalik. Experience of pre-operative genetic testing on surgical decision making in newly diagnosed breast cancer patients [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-12-13.