The results of a Phase III clinical trial suggest that starting Herceptin® (trastuzumab) during chemotherapy for early-stage, HER2-positive breast cancer may be more effective than starting Herceptin after chemotherapy has been completed. These results were published in the Journal of Clinical Oncology.

Twenty to 25 percent of breast cancers overexpress (make too much of) a protein known as HER2. Overexpression of this protein leads to increased growth of cancer cells and a worse breast cancer prognosis. Fortunately, the development of drugs such as Herceptin that specifically target HER2-positive cells has improved prognosis for women with HER2-targeted breast cancer.

The optimal timing of Herceptin was evaluated in a Phase III clinical trial known as NCCTG N9831. The study enrolled women with Stage I-III HER2-positive breast cancer.  All women received chemotherapy with doxorubicin and cylophosphamide followed by paclitaxel, and some women also received Herceptin. Herceptin was started either at the same time as paclitaxel or later (after chemotherapy had been completed), and was given for a total of 52 weeks.

  • Women who received both Herceptin and chemotherapy had a lower risk of cancer recurrence than women who received chemotherapy alone.
  • Women who started Herceptin at the same time as paclitaxel appeared to derive the most benefit. Five-year disease-free survival was 84.4% among women who received concurrent Herceptin and paclitaxel, compared with 80.1% among women who started Herceptin after finishing treatment with paclitaxel. This result did not meet the criteria for statistical significance, however, suggesting that it could have occurred by chance alone.
  • Starting Herceptin at the same time as paclitaxel did not appear to substantially increase the risk of side effects compared with starting Herceptin after chemotherapy had been completed.

For women with early-stage, HER2-positive breast cancer, these results suggest that starting Herceptin during chemotherapy may produce better results than starting Herceptin after chemotherapy has been completed.

Reference: Perez EA, Suman VJ, Davidson NE et al. Sequential versus concurrent trastuzumab in adjuvant chemotherapy for breast cancer. Journal of Clinical Oncology. 2011;29:4491-4497.

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