Six cycles of adjuvant anthracycline-taxane-based chemotherapy compared with eight cycles for women with breast cancer.

Abstract

e12045 Background: 3rd generation adjuvant chemotherapy regimens for breast cancer include FEC every three weeks (Q3W) x 3 cycles and Docetaxel (D) Q3W or weekly paclitaxel (P1W) x 9 weeks (FEC-D/P1W) and AC Q3W x 4 followed by P1W x 12 weeks or D x 4 cycles (AC-P1W). These regimens were developed independently and have not been directly compared. Real world effect of weekly paclitaxel schedule is unknown. Methods: Women with stage 1-3 breast cancer who received 3rd generation adjuvant chemotherapy (with 1 year of adjuvant trastuzumab if HER2+) between 2010-2015 inclusive were identified in the New Zealand Breast Cancer Database. Taxane regimens Q3W D and P1W were grouped for analysis. We compared 5 year overall survival (OS) between shorter FEC-D/P1W (total 6 cycles) and longer AC-P1W or Docetaxel Q3W x 4 cycles (total 8 cycles). Patients who received other taxane schedules or non-standard duration of chemotherapy were excluded. Results: 772 women received the FEC-D/P1W regimen and 488 were treated with AC-P1W. The FEC-D/P1W had more grade II/III disease (96.4% v 93.8%), BMI ≥30 (44.7% v 34.5%), HER2 positive (37.8% v 23.6%) and higher chemotherapy completion rate (95.1% v 83.8%). The AC-P1W cohort had higher nodal positive cases (97.1% v 80.6%). Univariate analysis showed no statistical significance for age, BMI, ethnicity, histological subtype and surgery type but tumour grade, stage and hormone status were significant. We constructed a cohort (n = 926) matched for these factors. After median follow up 27 months, 5yr OS for case matched cohort is 87.4% for FEC-D/P1W v 86.4% for AC-D/P1W (p = 0.825) with HR 0.96 (95%CI 0.67-1.38) in favour of FEC-D/P1W. Conclusions: These results suggest one can de-escalate chemotherapy by using a 6 cycle anthracycline/taxane regimen offering an opportunity to reduce the burden of chemotherapy without compromising survival.