Abstract P1-20-13: Delayed breast cancer surgery in HER2 positive breast cancer

Introduction Delayed breast cancer surgery, especially in those with aggressive subtypes of breast cancer, is always a great concern but not an infrequent occurrence. This study aimed to determine how frequently this occurs and its impact on overall survival (OS), relapse free survival (RFS), breast cancer specific survival (BCSS) and distant metastasis free survival (DMF) in HER2 positive breast cancer. Methods Patients with tissue diagnosis proven HER2 amplified breast cancer who were surgically treated at the Revlon/UCLA Breast Center between 2002 and 2018 were included. Patients with a previous history of breast cancer, metastasis and no known follow-up were excluded. Delayed breast cancer surgery was defined as surgery that occurred more than 2 months from the time of diagnosis without neoadjuvant treatment or more than 2 months after the last cycle of neoadjuvant treatment. Patients without clear dates of diagnosis, beginning and ending of different treatments will be analyzed separately. Chi-squared test was used to compare clinicopathologic characteristics and types of treatment between the 2 groups: surgery delayed and non-delayed. Kaplan-Meier curve and log rank test were used in univariate analysis to identify candidate prognosticators between the two groups. Cox-regression analysis was applied to identify independent prognosticators for survival outcomes. Results Of the 304 patients with dates of diagnosis, surgery and chemotherapy, 263 had timely surgery and 41 (13.5%) had delayed surgery. There was no significant difference in age, ethnicity, TN staging, tumor grade, hormone receptor status, Ki67, type of surgery chosen, chemotherapy and radiation between the two groups. The median follow-up for the entire patient population was 74.5 months. Both univariate and multivariate analyses showed that tumor grade was inversely associated with OS. In the neoadjuvant treated group, 8 of 101patients (7.9%) had delayed surgery. Non-pCR and mastectomy were found to be associated with RFS (p=0.045 and p=0.033 respectively). Residual nodal metastasis after neoadjuvant was associated with worse DMFS. Of the 220 patients who had received adjuvant chemotherapy, 33 (15%) had delayed surgery. Delayed surgery was more frequent in patients who had mastectomy (p=0.030). In the univariate analysis, lack of chemotherapy (p=0.016), larger tumor (p=0.003), positive lymph node (p=0.044) and older age were associated with worse OS. High T stage was found negatively associated with BCSS (p=0.014) and DMFS (p=0.030). Positive nodes were also adversely associated with DMFS (p=0.034). In the multivariate analysis, no adjuvant chemotherapy and high T stage predicted worse OS. Delayed surgery did not affect survival outcomes in all groups including all patients treated with either neoadjuvant chemotherapy or surgery first group. Conclusion Delayed breast cancer surgery in HER2 amplified breast cancer was infrequent and did not impact survival outcomes. In the neoadjuvant setting, non-pCR and mastectomy were associated with worse survival outcome. In the surgery first group, lack of chemotherapy and higher pathologic T stage were adversely associated with OS. Citation Format: Ho Hur, Amy Le, Helena R Chang. Delayed breast cancer surgery in HER2 positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-20-13.