Impact of the Delayed Initiation of Adjuvant Chemotherapy in the Outcome of Triple Negative Breast Cancer

Abstract

Background: Adjuvant chemotherapy decreases the recurrence risk and improves survival rates; however, it is unclear whether a delayed initiation is associated with adverse outcomes, especially in triple negative breast cancer (TNBC). In this study, we evaluated the influence of the time to start adjuvant chemotherapy (TTC) in the outcomes of TNBC. Patients and methods: We retrospectively analyzed 15 years of data from patients with TNBC who received adjuvant chemotherapy at the Instituto Nacional de Enfermedades Neoplasicas (Lima, Peru). TTC was categorized into 4 groups: ≤ 30, 31 to 60, 61 to 90, and ≥ 91 days. We evaluated overall survival (OS) and distant recurrence-free survival (DRFS). Cox proportional hazard models were used to identify prognostic factors. Results: In total, 687 patients were included. The mean age at diagnosis was 49.1 years (SD, 11.8 years), and most (62.6%) patients had pathologic stage T2. The median TTC was 48.1 days (SD, 27.4 days); 189 (27.5%) received chemotherapy ≤ 30 days; 329 (47.9%), between 31 and 60 days; 115 (16.7%), between 61 and 90 days; and 54 (7.9%) in ≥ 90 days. In the multivariate analysis, a TTC between 31 and 60 days (hazard ratio [HR], 1.78; 95% confidence interval [CI], 1.17-2.72), 61 and 90 days (HR, 2.38; 95%CI, 1.43-3.97), and ≥ 91 days (HR, 2.45; 95% CI, 1.32-4.55) was associated with an increased mortality in contrast with a TTC < 30 days. Although a TTC between 31 and 60 days, 61 and 90 days, and ≥ 91 days was associated with an increased risk of DRFS (HR, 1.86; 95% CI, 1.24-2.79; HR, 2.34, 95% CI, 1.42-3.867; and HR, 3.16; 95% CI, 1.78-5.61, respectively). Conclusion: A delaying in TTC ≥ 30 days was associated with poorer outcomes. Our data suggest that several efforts should be conducted to avoid a delayed TTC in patients with TNBC.