Becker, Heather P.

1007 Background: Determining optimal adjuvant chemotherapy for early stage breast cancer depends on efficacy and toxicity. We sought to determine if T is equivalent to AC but with reduced toxicity. Methods: Pts with operable breast cancer with 0-3 positive nodes were enrolled on a 2x2 factorial design study which addressed (1) superiority of 6 vs. 4 cycles of therapy (previously reported, Shulman, JCO 2012) and (2) equivalence of single-agent T to standard AC, defined as upper bound of 95% confidence interval (CI) of hazard ratio (HR) of T vs. AC < 1.30 for the primary endpoint of relapse-free survival (RFS). A planned target of 567 RFS events required 4,646 pts with 4 yrs FU. At activation in 2002, T (80mg/m2) was q1wk for 12 or 18 wks and AC (60/600 mg/m2) was q3wk for 4 or 6 cycles. In 2003 (570 pts enrolled) schedules were revised to 4 or 6 cycles q2wk for both T (175 mg/m2) and AC. The 6-cycle arms were dropped in 2008 (3,171 pts enrolled) due to slow accrual. Relative effectiveness of T to AC is shown by hazard ratio (HR). Logrank p-values are measures of discordance but are not relevant for the equivalence question and are not adjusted for multiple comparisons. Results: After enrolling 3,871 pts, the study closed in 2010 due to slowing accrual. With a median follow-up of 6.1 yrs there are 437 RFS events. The HR of 1.26 (95% CI: 1.05-1.53; p = 0.02) does not allow a conclusion of equivalence of T with AC. With 266 deaths the HR for overall survival (OS) is 1.27 (95% CI=1.00-1.62; p = 0.05), favoring AC. The estimated absolute advantage of AC at 5 yrs is 3% (91 vs. 88%) for RFS and 1% (95 vs. 94%) for OS. All 9 treatment-related deaths were in pts receiving AC and are included in the survival analysis. The incidence of Grade 3+ toxicity for AC vs T was 33% vs. 4% for hematologic toxicity and 36% vs 22% for non-hematologic toxicity. Conclusions: This trial did not show equivalence of T to AC, a conclusion that is very unlikely to change with additional follow-up. T was less toxic than AC. Clinical trial information: CDR0000069444/NCT00041119.

PurposeOptimal adjuvant chemotherapy for early-stage breast cancer balances efficacy and toxicity. We sought to determine whether single-agent paclitaxel (T) was inferior to doxorubicin and cyclophosphamide (AC), when each was administered for four or six cycles of therapy, and whether it offered less toxicity.Patients and MethodsPatients with operable breast cancer with 0 to 3 positive nodes were enrolled onto the study to address the noninferiority of single-agent T to AC, defined as the one-sided 95% upper-bound CI (UCB) of hazard ratio (HR) of T versus AC less than 1.30 for the primary end point of relapse-free survival (RFS). As a 2 × 2 factorial design, duration of therapy was also addressed and was previously reported.ResultsWith 3,871 patients enrolled onto the trial, a median follow-up period of 6.1 years, and 437 RFS events, we achieved an HR of 1.26 (one sided 95% UCB, 1.48; favoring AC does not allow a conclusion of noninferiority of T with AC; UCB > 1.3). With 266 patient deaths, the HR for overall survival (OS) was 1.27 favoring AC (UCB, 1.56). The estimated absolute advantage of AC at 5 years is 3% for RFS (91 v 88%) and 1% for OS (95 v 94%). All nine treatment-related deaths were patients receiving AC and are included in the analyses of both RFS and OS. Hematologic toxicity was more common in patients treated with AC, and neuropathy was more common in patients treated with T.ConclusionThis trial did not show noninferiority of T to AC, a conclusion that is unlikely to change with additional events and follow-up. T was less toxic than AC.

PurposeThe ideal duration of adjuvant chemotherapy for patients with lower risk primary breast cancer is not known. Cancer and Leukemia Group B trial 40101 was conducted using a phase III factorial design to define whether six cycles of a chemotherapy regimen are superior to four cycles. We also sought to determine whether paclitaxel (T) is as efficacious as doxorubicin/cyclophosphamide (AC), but with reduced toxicity.Patients and MethodsBetween 2002 and 2008, the study enrolled women with operable breast cancer and zero to three positive nodes. Patients were randomly assigned to either four or six cycles of either AC or T. Study stratifiers were estrogen receptor/progesterone receptor (ER/PgR), human epidermal growth factor receptor 2 (HER2), and menopausal status. After 2003, all treatment was administered in dose-dense fashion. The primary efficacy end point was relapse-free survival (RFS).ResultsA total of 3,171 patients were enrolled; 94% were node-negative and 6% had one to three positive nodes. At a median follow-up of 5.3 years, the 4-year RFS was 90.9% and 91.8% for six and four cycles, respectively. The adjusted hazard ratio (HR) of six to four cycles regarding RFS was 1.03 (95% CI, 0.84 to 1.28; P = .77). The 4-year OS was 95.3% and 96.3% for six and four cycles, respectively, with an HR of six to four cycles of 1.12 (95% CI, 0.84 to 1.49; P = .44). There was no interaction between treatment duration and chemotherapy regimen, ER/PgR, or HER2 status on RFS or OS.ConclusionFor women with resected primary breast cancer and zero to three positive nodes, we found no evidence that extending chemotherapy regimens of AC or single-agent T from four to six cycles improves clinical outcome.