Retrospective analysis of the impact of anthracycline dose reduction and chemotherapy delays on the outcomes of early breast cancer molecular subtypes

Abstract

BACKGROUND: The objective of study was to determine the effect of anthracycline dose reduction and chemotherapy delays on 5-year overall survival in patients with stage I-III breast cancer, to establish the impact of molecular subtypes on the anthracycline modification effects and to analyze reasons for such chemotherapy scheme modifications. METHODS: Medical records of patients with stage I-III breast cancer were reviewed. Inclusion criteria involved stage I- III breast carcinoma; radical surgery performed and 4 courses of AC regimen (doxorubicin and cyclophosphamide), or at least 6 courses of FAC regimen (fluorouracil, doxorubicin and cyclophosphamide) completed; no neoadjuvant chemotherapy applied; no taxane group medications administered; medical records maintain comprehensive data on treatment and follow-up. 5- year overall survival were analyzed using Kaplan-Meier and Cox proportional hazards models. RESULTS: Significant 3.17 times higher death risk at 5 year period in patients who experienced anthracycline dose reduction compared with patients who did not experience any modifications was established (HR = 3.17, 95% CI 1.7-5.9, p < 0.001). Increased death risk in patients who experienced both chemotherapy dose reduction and treatment delays compared with patients who did not experience any modifications was also established (HR = 2.76, 95% CI 1.3-5.6, p < 0.05). 5- year overall survival was affected by anthracycline dose reduction by more than 15% in ER-HER2- group (80% v. 55.6%, p = 0.015), ER + HER2- group (90.7% v. 64.9%, p < 0.01) and ER+/-HER2+ group (100% v. 84.4%, p = 0.019). 5-year overall survival was affected by chemotherapy delays more than 2 cycles in ER-HER2- group (79.2% v. 51.4%, p = 0.002), ER + HER2- group (86.3% v. 58.8%, p = 0.014) and there was no difference in ER+/-HER2+ group. [...].