Clinicians can now recommend that trastuzumab be given concurrently with chemotherapy to achieve maximum benefit in terms of disease-free survival.
Researchers, led by Dr. Edith Perez, director of the breast cancer programme at the Mayo Clinic in Jacksonville, Florida, USA, found a 25 percent reduction in the risk of breast cancer recurrence when trastuzumab was administered concurrently, rather than following chemotherapy.
Perez said these findings are very important and estimated that they will inform treatment decisions for about 50,000 women in the United States and 200,000 women around the world every year.
"Often the research community conducts studies that conclude with 'that was interesting, but let's do more research.' This is an important finding on how we can help prevent breast cancer recurrence and improve survival," said Perez.
All patients enrolled in this phase III trial were receiving standard chemotherapy of doxorubicin and cyclophosphamide followed by paclitaxel.
The researchers conducted two separate comparisons.
The first included 2,448 patients randomly assigned to chemotherapy alone or chemotherapy followed by trastuzumab. After 5.5 years, the researchers observed 386 events. After adjustment for possible confounding variables, they found that event-free survival increased from 72 percent with chemotherapy alone to 80 percent with chemotherapy followed by trastuzumab.
The second comparison included 1,903 women. The researchers compared those who received trastuzumab after chemotherapy with those who received it concurrently with paclitaxel. At five years, disease-free survival increased from 80 percent to 84 percent.
"This study has global implications. In the United States, Herceptin is approved for use either following or concurrently with chemotherapy," said Perez. "However, currently in some countries trastuzumab is only approved for use following chemotherapy as adjuvant therapy for HER2-positive breast cancer. We hope our findings will change those policies. In the United States, this will clearly inform physician decision making."