Abstract P5-10-02: Clinical Outcome of Two Sequences of Administering Paclitaxel (P) and Anthracyclines (A) as Primary Systemic Therapy (PST) and Adjuvant Chemotherapy (ACT) in Breast Cancer (BC) Patients: A Retrospective Analysis from the M. D. Anderson Cancer Center (MDACC)

Abstract

Abstract Background: P-and A-based regimens are widely used as PST and ACT of early BC. It is unknown whether the efficacy of such combinations is affected by their sequence of administration. The purpose of this retrospective analysis was to assess the clinical outcome of two different sequences of P and A in pts receiving PST and ACT. Methods: We analyzed 3,010 pts (1,414 PST and 1,596 ACT) with stage I — III BC treated between 1994 -2009. These pts were identified through our prospective online MDACC breast cancer database. Pts treated with trastuzumab, docetaxel or adriamycin/cyclophosphamide-regimen were excluded. Pathological complete response (pCR) was defined as no residual invasive disease in breast and ipsilateral axillary lymph nodes. Results: PST cohort included 1.071 pts (75%) with clinical stage I-IIIA and 343 (24.2%) stage IIIB-IIIC BC; 1,188 pts (84%) received the sequence P→A and 226 pts (16%) A→P. In the PST cohort 958 pts (67.7%) and 161 (11.3%) had hormone-receptor (HR) positive (+) and HER-2 + BC, respectively. ACT cohort consisted of 1,503 pts (94%) with pathological stage I-IIIA and 93 (5.82%) stage IIIB-IIIC. 1,196 pts (75%) received the sequence P→A, and 400 pts (25%) A→P. In the ACT cohort 1,122 (70.3%) and 93 (3.9%) had HR+ and HER2+ BC, respectively. Both cohorts of pts were balanced by HR-status, clinical stage, and menopausal status. The combined p-values for ACT and PST cohorts were calculated and they were significant for both RFS (p=0.022) and OS (p=0.002). In univariate analysis the sequence A→P was associated with inferior outcome. In Cox multivariate analysis, after stratification for period at diagnosis and adjustment for age, clinical stage, HR status, grade, and LVI the A→P sequence administered as PST was associated with significantly higher risk of relapse (HR 1.49; CI 1. 10-2.03; p=0.01) but not death (HR 1.28; CI 0.90-1.84; p=0.17). In the ACT cohort, the Cox multivariate analysis, after stratification for age, HR status, HER2 the sequence A→P was significantly associated with higher risk of death (HR 2.02; CI 1.33-3.06; p=0.001) but not relapse (HR 1.21; CI 0.82-1.79; p=0.33). Conclusions: The P→A sequence compared to the A→P sequence is associated with lower risk of relapse and death in PST and ACT, respectively. This retrospective analysis is hypothesis-generating and should lead to a prospective randomized trial to compare the two sequences as PST or ACT in locally advanced or early BC, respectively. Primary Systemic Therapy (N=1,414) Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-10-02.