Docetaxel significantly improves overall survival and median time to disease progression compared with paclitaxel in women with advanced breast cancer whose disease had progressed despite previous anthracycline-based chemotherapy, according to an article in the August 20th issue of the Journal of Clinical Oncology.

The phase III trial randomized 449 patients with locally advanced or metastatic breast cancer who failed an anthracycline-containing chemotherapy regimen to docetaxel (100 mg/m2, 1-hour intravenous infusion every 21 days/ 225 women) or paclitaxel (175 mg/m2, 3-hour intravenous infusion every 21 days/224 women).

Docetaxel was associated with a significantly longer median time to progression than paclitaxel (5.7 months vs. 3.6 months) and significantly longer median overall survival (15.4 months vs. 12.7 months).

Among patients evaluable for response (tumor shrinkage), those who received docetaxel had significantly higher response rates (37.0% vs. 26%, p=0.02) and significantly longer median duration of response (7.5 months vs. 4.6 months, p=0.01), than those who received paclitaxel.

"This is the first clinical trial to directly compare these extensively used taxanes. Preclinical and laboratory evidence suggested that docetaxel and paclitaxel are different," said Stephen E. Jones, MD, lead author of the study. "The results from this head-to-head study provide oncologists with the clinical evidence of these differences. Rarely have we seen trials for the treatment of women with advanced breast cancer that demonstrate significant differences in survival."

Patients in the study continued to receive study drug as long as they responded to treatment. Patients received a median of six cycles of docetaxel compared with a median of four cycles of paclitaxel. The use of G-CSF, a bone marrow growth factor, was only permitted following an initial episode of grade 4 leukopenia or neutropenia persisting longer than seven days or associated with fever.

The incidence of treatment-related hematologic and nonhematologic adverse events was greater for docetaxel than for paclitaxel; however, quality of life scores were not statistically different between treatment groups over time.