Abstract P1-12-07: Delayed initiation of adjuvant chemotherapy among breast cancer patients: A population-based study

Abstract

Abstract BACKGROUND: Adjuvant chemotherapy improves outcomes of breast cancer patients; however the optimal timing to initiation of chemotherapy remains unknown. No study has evaluated the relationship between time to chemotherapy (TTC) and outcome in a population-based study of patients treated with contemporary regimens according to tumor subtype. In this large study we identified the determinants associated with a delay in the initiation of chemotherapy and determined whether TTC is related to outcome. METHODS: Breast cancer patients diagnosed with stage I-III breast cancer between 2005-2010 and treated with adjuvant chemotherapy were identified in the California Cancer Registry. TTC was defined as number of days between surgery and the day the first dose of adjuvant chemotherapy was administered. Delayed TTC was defined as >91 days. Logistic regression and Cox-proportional hazard modeling were used. RESULTS: A total of 24,843 patients were included. Factors associated with delays in TTC included low socioeconomic status, reconstructive surgical procedure, non-private insurance and Hispanic or non-Hispanic black race/ethnicity. Compared to patients receiving chemotherapy within 31 days from surgery, there was no evidence of adverse outcome among those with TTC of 31-60 or 60-90 days. To the contrary, patients treated >91 days from surgery experienced statistically significant worse overall survival (OS) (HR=1.34; 95%CI 1.15-1.57) and worse breast cancer specific survival (BCSS) (HR=1.27; 95%CI 1.05-1.53). In a subgroup analysis according to breast cancer subtype, TTC >91 days had a statistically significant detrimental impact among patients with triple negative breast cancer (TNBC) in terms of both OS (HR=1.53; 95%CI 1.17-2.00) and BCSS (HR=1.53; 95%CI 1.17-2.07). CONCLUSIONS: In this large cohort of breast cancer patients treated with contemporary regimens, a delaying in the initiation of adjuvant chemotherapy >91 days was associated with adverse outcomes. A delay in TTC is particularly detrimental among patients with TNBC. The majority of the determinants of delays in chemotherapy initiation are socio-demographic in nature. As medical providers we must make every effort to provide timely care to all our patients so they can receive the full benefit of our current treatments. Citation Format: Chavez-MacGregor M, Clark CA, Lichetensztajn DY, Giordano SH. Delayed initiation of adjuvant chemotherapy among breast cancer patients: A population-based study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-12-07.