Abstract GS2-05: Impact of the delayed initiation of adjuvant chemotherapy in the outcomes of triple negative breast cancer

Background: Adjuvant chemotherapy decreases the risk of recurrence and improves survival rates but it is unclear whether a delayed initiation is associated with adverse outcomes. Information available is especially scarce for triple negative breast cancer (TNBC) which represents a high-risk group. We evaluated the influence of time to chemotherapy (TTC) on TNBC patient9s survival outcomes. Methods: We retrospectively analyzed the data using the medical records of TNBC patients who received adjuvant chemotherapy at Instituto Nacional de Enfermedades Neoplasicas between 2000-2014. TTC was defined as the number of days between surgery and the first dose of chemotherapy. Patients were categorized into 4 groups according to TTC: ≤30, 31-60, 61-90, ≥91 days. We evaluated recurrence-free survival (RFS) and overall survival (OS). Logistic regression and Cox proportional hazard models were used. Results: 687 patients were included. Mean age at diagnosis was 49.15 (range, 21-89) and most patients were stage II (60.1%) or III (29.45%). They received either anthracyclines or anthracyclines and taxane-based chemotherapy (96.1%). Median TTC was 41 days. 189 (27.5%) received chemotherapy at or before 30 days; 329 (47.9%), between 31 and 60 days; 115 (16.7%), between 61 and 90 days and; 54 (7.9%) beyond 90 days. Median follow-up was 101 months. 10y-DFS was 81.4%, 68.6%, 70.8% and 68.1% among patients who received chemotherapy ≤30, 31-60, 61-90, ≥91 days, respectively (p=0.005). Accordingly, 10y-OS was 82%, 67.4%, 67.1% and 65.1% among patients who received chemotherapy ≤30, 31-60, 61-90, ≥91 days, respectively (p=0.003). In the multivariate analysis, TTC was an independent prognostic factor for RFS and OS. Patients with TTC of 31-60 days (HR, 1.92; 95% CI, 1.225 to 2.998), 61-90 days (HR, 2.38; 95% CI, 1.354 to 4.172) and ≥91days (HR, 2.47; 95% CI, 1.250 to 4.886); had worse survival compared with those who initiated treatment in the first 30 days after surgery. Patients with TTC of 31-60 days (HR, 1.94; 95% CI, 1.243 to 3.034), 61-90 days (HR, 2.45; 95% CI, 1.402 to 4.265) and ≥91days (HR, 2.79; 95% CI, 1.418 to 5.506); had worse survival compared with those who initiated treatment in the first 30 days after surgery. Conclusion: Delayed initiation of adjuvant chemotherapy in TNBC patients over 30 days is associated with a decrease in RFS and OS rates. The greater the delay, the worse the outcomes. As this represents a feasible opportunity for improvement, every attempt should be made to avoid delayed adjuvant chemotherapy initiation in this high-risk group of patients. Citation Format: Morante Z, Ruiz R, De la Cruz - Ku G, Namuche F, Mantilla R, Lujan MG, Fuentes H, Schwarz J, Aguilar A, Neciosup S, Gomez H. Impact of the delayed initiation of adjuvant chemotherapy in the outcomes of triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS2-05.