As reported in the Journal of Clinical Oncology by Charles E. Geyer Jr, MD, and colleagues, long-term follow-up of the ABC trials (USOR 06-090, NSABP B-46-I/USOR 07132, and NSABP B-49 [NRG Oncology]) showed that noninferiority of adjuvant nonanthracycline therapy was not demonstrated vs anthracycline-based regimens in terms of invasive disease–free survival in patients with high-risk early breast cancer.
Charles E. Geyer Jr, MD
Study Details
The ABC trials compared adjuvant anthracycline-based therapy (standard regimens of docetaxel or paclitaxel with cyclophosphamide and doxorubicin) vs nonanthracycline therapy (six cycles of docetaxel and cyclophosphamide) in 4,181 patients with high-risk early breast cancer. At primary joint efficacy analysis at a median follow-up of 3.3 years, nonanthracycline therapy was not found to be noninferior to anthracycline-based treatment in terms of invasive disease–free survival.
Key Findings
Median follow-up for the current analysis was 6.9 years. Invasive disease–free survival at 5 years was 85.1% in the nonanthracycline group vs 86.7% in the anthracycline group. The hazard ratio was 1.14 with an 80% confidence interval (CI) of 1.04 to 1.25; since the upper bound did not exclude the original prespecified inferiority threshold of 1.18, noninferiority of nonanthracycline therapy was not shown.
Recurrence-free interval rates at 5 years were 88.2% in the nonanthracycline group vs 91.0% in the anthracycline group (HR= 1.38, 95% CI = 1.16–1.65, P = .0003). Tests for heterogeneity were significant for hormone receptor (HR) status (P = .02), favoring anthracycline regimens for the HR-negative subgroup. The hazard ratio for nonanthracycline vs anthracycline regimens for recurrence-free interval was 1.90 (95% CI = 1.39–2.61, P < .0001) among HR-negative patients. The hazard ratio for invasive disease–free survival among HR-negative patients was 1.30 (95% CI = 1.02–1.67, P = .04), also favoring the anthracycline group.
No significant difference in overall survival was observed between the nonanthracycline group and the anthracycline group (HR = 1.05, 95% CI = 0.87–1.26, P = .64); 5-year rates were 91.8% vs 92.4%.
The investigators stated, “Review of the type of invasive disease–free survival events in the groups suggested reductions in cancer recurrences achieved with anthracycline regimens were offset by late leukemias and deaths unrelated to breast cancer.
They concluded, “Long-term analysis of invasive disease–free survival, the primary endpoint of the ABC trials, remains consistent with the original analysis….”
Dr. Geyer, of NSABP Foundation/NRG Oncology and UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the National Cancer Institute, Susan G. Komen for the Cure, Sanofi, and Genentech. For full disclosures of the study authors, visit ascopubs.org.
