Adding trastuzumab (Herceptin) to standard anthracycline/taxane–based chemotherapy continued to produce disease-free and overall survival benefits in patients with HER2-positive breast cancer enrolled in the North Central Cancer Treatment Group (NCCTG) N9831 and the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-31 trials.
“These trials were designed similarly, enabling a joint analysis of the two studies,” wrote the authors of the latest analysis, published in the Journal of Clinical Oncology. At 3.9 years of median follow-up, the new analysis confirmed results from two interim analyses showing reductions in disease-free survival events, defined as local, regional, or distant recurrence of breast cancer; a contralateral breast cancer; a second primary cancer; or death as a result of any cause.
The first analysis, with a median follow-up of 2 years, found that the relative reduction in disease-free survival event rate was 52% (P < .001). The second interim analysis, with a median follow-up of 2.9 years, demonstrated a continued reduction in the disease-free survival event rate and a statistically significant 35% reduction in mortality (P < .001).
“With the additional follow-up, the relative reduction in disease-free survival event rate was 48% (P < .001), and the relative reduction in death rate was 39% (P < .001),” the authors wrote. “Thus, our data demonstrate long-term continued benefit with trastuzumab administered concurrently with chemotherapy (anthracycline/cyclophosphamide followed by paclitaxel plus trastuzumab, with 1 year of trastuzumab treatment). Absolute differences in disease-free survival increased by number of nodes; it was most pronounced for patients with 10 involved nodes, who had an unprecedented 27% absolute improvement.”
The N9831 and B-31 trials “assessed the efficacy and safety of adding 52 weeks of trastuzumab to standard anthracycline/taxane-based chemotherapy (doxorubicin plus cyclophosphamide [AC] followed by paclitaxel),” the authors explained. The latest findings are based on all 4,045 patients enrolled in these treatment arms before enrollment ended. The women had to be older than 18 years with primary, operable, and histologically confirmed node-positive (both trials) or high-risk node-negative invasive breast cancer (N9831 only), with no evidence of metastases, and strongly HER2-positive tumors.
“A number of adjuvant treatment combinations of chemotherapy with trastuzumab are now available, allowing physicians to select a regimen they consider most appropriate for patients with early-stage invasive HER2-positive breast cancer. Longer-term follow-up and identification of predictive biomarkers will provide further insight into optimal trastuzumab adjuvant therapies,” the authors concluded.
Perez EA, et al: J Clin Oncol. July 18, 2011 (early release online).