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 > or = 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 were randomly assigned to receive either four cycles of standard-dose AC (60/600 mg/m(2); n = 510), or TC (75/600 mg/m(2); n = 506), administered by intravenous infusion every 3 weeks. The median age in women younger than 65, was 50 years (range, 27 to 64) and for women > or = 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. 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.