Trastuzumab did not decrease risk for relapse in node-positive breast cancer

Treatment with trastuzumab after adjuvant chemotherapy in patients with axillary-node–positive HER2 over-expressing breast cancer did not significantly reduce relapse risk, according to the findings from the FNCLCC-PACS 04 trial.

The trial enrolled 3,010 patients who were randomly assigned to adjuvant anthracycline-based chemotherapy with or without docetaxel. Patients who had tumors that over expressed HER2 were then randomly assigned to trastuzumab (Herceptin, Genentech) 6 mg/kg every three weeks for a year (n=260) or to a year of observation (n=268). Median follow-up was 47 months.

Ten percent of patients assigned to trastuzumab did not receive the treatment. Among patients assigned to at least one dose, 196 were administered at least six months of treatment and 176 were administered 16 or more injections. Of patients who discontinued treatment, 18% cited cardiac events as the reason for discontinuation.

Researchers recorded 70 disease-free survival events in the observation group and 59 DFS events in the treatment group. There was a 14% reduction in risk for relapse in the group assigned to trastuzumab; however, the association did not reach statistical significance.

The three-year DFS rate was similar in both groups at 77.9% (95% CI, 72.2-82.5) in the observation group and 80.9% (95% CI, 75.2-85.3) in the treatment group. There were 22 deaths in the trastuzumab group and 18 in the observation group. The three-year OS rate was 95% for patients assigned to trastuzumab and 96% for patients assigned to observation.

“The analysis of the second part of the PACS04 trial did not find an overall statistically significant relapse risk reduction for trastuzumab given as sequential treatment,” the researchers wrote. “More follow-up is needed for a meaningful statistical comparison.”

Spielmann M. J Clin Oncol. 2009;doi:10.1200/JCO.2009.23.0946.