Population-Based Comparison of CEF and AC/T, Two Adjuvant Chemotherapy 'Standards' for Early Stage Breast Cancer.

Abstract

Abstract Introduction: Anthracyclines and taxanes in adjuvant therapy have improved the outcomes of women with early stage breast cancer. The first analysis of the phase III NCIC-MA21 trial comparing the three 6 month adjuvant regimens CEF, AC followed by q3weekly paclitaxel(AC/T) and dose dense EC followed by paclitaxel (EC/T) revealed inferior Relapse Free Survival for AC/Tversus CEF (HR 1.49[1.12,1.99]) and EC/T (HR1.68 [1.25-2.27]). The purpose of this population based analysis is to evaluate the characteristics and outcome of women with high-risk breast cancer treated with CEF vs q3weekly AC/T.Methods: The British Columbia Breast Cancer Outcomes Unit (BCOU) and Pharmacy databases were used to identify patients with node positive or high-risk node negative breast cancer between years 2000-2004 treated with adjuvant chemotherapy with either CEF or AC/T. Both regimens were available and recommended for high risk breast cancer during the time of the study. Patients with cTx, pTx tumours, previous or synchronous breast cancer and those with with locally advanced/inflammatory breast cancer were excluded. Patient and tumour characteristics were compared across study cohorts.Univariate comparisons of overall survival (OS) and breast cancer specific survival (BCSS) were performed using the Kaplan-Meier method. Propensity score models were used to compare outcomes in the two cohorts, adjusting for differences in prognostic and other treatment variables.Results: Between 2000-2004, 774 (CEF=557, AC/T=217)women with breast cancer met the inclusion criteria. Median follow-up for CEF was 4.7 years and for AC-T was 3.0 years. CEF-treated patients had more LVI (p=0.0001) and node +ve disease (p<0.0001), were younger (p<0.0001), more likely ER+ (p<0.0001), less likely to have grade 3 tumours (p<0.0001) and received higher rates of both hormones (p<0.0001) and radiation therapy to regional nodes (p<0.0001). Univariate analyses showed better outcomes for the CEF-treated cohort for both OS (p=0.0056) and BCSS (p=0.0012). Propensity score models also favoured the CEF cohort with adjusted HR's of 0.47 (95% CI: 0.27, 0.83; p=0.0086) and 0.40 (95% CI: 0.22, 0.71; p=0.0020) for OS and BCSS respectively.Conclusion: Between 2000 and 2004, women in British Columbia treated with adjuvant CEF had higher risk breast cancer than patients who received AC/T. However, CEF-treated patients have better outcomes than those receiving AC/T. Both univariate and adjusted analyses favour the CEF cohort. These population-based outcomes are consistent with the finding of the NCIC-MA21 randomized trial. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2084.