Abstract P2-16-12: Real-world outcomes in patients receiving neoadjuvant chemotherapy for early-stage triple-negative breast cancer

Abstract

Abstract Background: Standard of care treatment for early-stage triple-negative breast cancer (ESTNBC) is chemotherapy. Minimal research has examined real-world effectiveness outcomes in patients with ESTNBC. Methods: This retrospective observational study evaluated event-free survival (EFS) and overall survival (OS) in patients with ESTNBC from US community oncology practices. Eligible patients were female and age 18+ at the time of stage II, IIIA or IIIB ESTNBC diagnosis that occurred between 3/2008 and 3/2016. All eligible patients received definitive surgery following neoadjuvant systemic therapy, with or without adjuvant systemic therapy. Kaplan-Meier analysis and Cox regression models were used to evaluate EFS and OS from the start of neoadjuvant therapy. EFS events are recurrence, second primary malignancy or death, whichever occurred first. Results: Of 308 patients included in the study, 236 (76.6%) received neoadjuvant only (Neo); 72 (23.4%) received neoadjuvant plus adjuvant systemic therapy (Neo+Adj). Overall, mean age was 52.1 years (SD 11.3), 56.8% were White (n=175), 35.7% African-American (n=110), 7.4% other/undocumented (n=23). Demographic characteristics did not differ between treatment groups. Two-thirds of patients (66.6%, n=205) were stage II at diagnosis, 33.4% (n=103) were stage IIIA or IIIB at diagnosis (22.4% and 11.0%, respectively). Most (82.8%, n=255) had grade 3 tumors and 42.2% were peri/postmenopausal (n=130) at diagnosis. Evidence of pathologic complete response (pCR) was observed in 41.2% of patients (n=127), while 57.5% of patients (n=177) had residual disease, and 1.3% (n=4) had undocumented/other response status. pCR was observed in 47.5% of Neo and 20.8% of Neo+Adj patients. Median EFS for all patients was not reached while mean EFS was 55.6 months (SD 1.6). Stage at diagnosis, surgery type and BMI were significant predictors of an EFS event, with stage II patients having less risk than stage III patients (Hazard ratio [HR]: 0.496 p<0.001). Patients with partial mastectomy had less risk of an EFS event than those with mastectomy (HR: 0.548, p=0.011). Higher BMI was associated with greater risk of an EFS event (HR: 1.035, p=0.014). Median OS for all patients was not reached while mean OS was 70.3 months (SD 1.5). Stage at diagnosis, surgery type and BMI were significant predictors of OS; patients with stage II had a reduced risk of death compared to stage III patients (HR: 0.299, p<0.001). Patients with partial mastectomy had less risk of death than those with mastectomy (HR: 0.483, p=0.020). Higher BMI was associated with greater risk of an EFS event (HR: 1.043, p=0.019). Conclusions: This real-world study found that stage at diagnosis, surgery type and BMI were significant predictors of EFS and OS events from the start of neoadjuvant treatment. This study highlights the need for improved therapies to extend EFS and OS for patients with ESTNBC. Given the association between pCR and EFS and OS, further analyses will evaluate EFS and OS by pCR status for each group. Time to recurrence analyses are also planned. Citation Format: Whitney C Rhodes, Santosh Gautam, Amin Haiderali, Min Huang, Jan Sieluk, Karen E Skinner, Lee S Schwartzberg. Real-world outcomes in patients receiving neoadjuvant chemotherapy for early-stage triple-negative 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 P2-16-12.