Administering paclitaxel before anthracyclines leads to better relapse-free survival rates for patients with breast cancer than does using the drugs in the reverse order.

A retrospective analysis of 1,414 patients with breast cancer (stages I – III) who underwent primary systemic therapy and 1,596 on adjuvant chemotherapy

evaluated the clinical outcomes of the two different sequences of paclitaxel and anthracyclines over a 15-year period. Both cohorts were balanced by hormone-receptor status, clinical stage, and menopausal status.

The analysis revealed that anthracyclines-before-paclitaxel yielded inferior outcomes. In primary systemic therapy, this combination was associated with a significantly higher risk of relapse, but not death. In the adjuvant-chemotherapy group, anthracyclines-before-paclitaxel was significantly associated with a higher risk of death, but not relapse.

The 5-year relapse-free survival rate for those receiving paclitaxel before anthracyclines as primary systemic therapy was 79%, compared with 61.2% when the reverse order was used. The 5-year overall survival rate was 84.2% when paclitaxel was used first in primary systemic therapy, compared with 71.3% when the regimen started with anthracyclines.

When used as adjuvant chemotherapy, paclitaxel-first was associated with a 5-year relapse-free survival rate of 88.8% and a 5-year overall survival rate of 93.1%. When anthracyclines preceded paclitaxel, those rates fell to 79.5% and 83.2%, respectively.

“This retrospective analysis is hypothesis-generating and should lead to a prospective randomized trial to compare the two sequences as [primary systemic therapy] and [adjuvant chemotherapy] in locally advanced or early [breast cancer], respectively,” wrote Ricardo Hugo Alvarez, MD, of the M. D. Anderson Cancer Center (Houston, Texas), and fellow investigators in an abstract presented at the recent San Antonio Breast Cancer Symposium (www.abstracts2view.com/sabcs10/view.php?nu=SABCS10L_406&terms=).