Docetaxel With Cyclophosphamide Is Associated With an Overall Survival Benefit Compared With Doxorubicin and Cyclophosphamide: 7-Year Follow-Up of US Oncology Research Trial 9735

Abstract

Purpose: We previously reported that four cycles of docetaxel/cyclophosphamide (TC) produced superior disease-free survival (DFS) compared with four cycles of doxorubicin/cyclophosphamide (AC) in early breast cancer. Older women are under-represented in adjuvant chemotherapy trials. In our trial 16% of patients were ≥ 65 years. We now report 7-year results for DFS and overall survival (OS) as well as the impact of age, hormone receptor status, and HER2 status on outcome and toxicity. Patients and Methods: Patients were randomly assigned to receive either four cycles of standard-dose AC (60/600 mg/m²; n = 510), or TC (75/600 mg/m²; n = 506), administered by intravenous infusion every 3 weeks. Results: The median age in women younger than 65, was 50 years (range, 27 to 64) and for women ≥ 65 was 69 years (range, 65 to 77). Baseline characteristics in the two age subgroups were generally well matched, except that older women tended to have more lymph node involvement. At a median of 7 years follow-up, the difference in DFS between TC and AC was significant (81% TC v 75% AC; P = .033; hazard ratio [HR], 0.74; 95% CI 0.56 to 0.98) as was OS (87% TC v 82% AC; P = .032; HR, 0.69; 95% CI, 0.50 to 0.97). TC was superior in older patients as well as younger patients. There was no interaction of hormone-receptor status or HER-2 status and treatment. Older women experienced more febrile neutropenia with TC and more anemia with AC. Conclusion: With longer follow-up, four cycles of TC was superior to standard AC (DFS and OS) and was a tolerable regimen in both older and younger patients.