In women with advanced (or metastatic) breast cancer, treatment with the breast cancer drug Herceptin is associated with prolonged survival but also increases the risk of developing heart problems, a new systematic review shows. However, the review, published in the Cochrane Library, concludes that the benefits outweigh the harmful risks.
The review focuses on treatment for women with advanced stage breast cancer who have tested positive for HER2 (human epidermal growth factor receptor 2), which affects about 1 in 5 women. HER2 is a protein on the surface of breast cells that encourages tumor cells to grow and divide. The prognosis for HER2-positive patients is usually worse because the high levels of HER2 on their tumor cells make their cancer more aggressive.
Herceptin is designed to target these specific types of tumors. It has been approved for the treatment of HER2-positive advanced breast cancer since 1998 in the U.S. and 2002 in the UK.
The authors reviewed data from 7 trials involving a total of 1497 HER2-positive women with metastatic breast cancer. The women were given Herceptin in combination with other drugs, either as a first-line treatment or later therapy, when their cancer had progressed.
Overall survival rates 2 years after starting the trials were higher for women who were given Herceptin than for those on regimens that did not include the drug. Women on Herceptin also gained another 2 to 11 months without further progression of their cancers. The drug was most effective when it was used as a first-line treatment or in combination with the chemotherapy drug class called taxanes.
However, the drug led to an increased risk of heart failure. With standard therapies, the equivalent of 300 in every 1000 women survived at 2 years and only 10 developed heart problems. When Herceptin was added, 373 survived but 35 developed heart problems that required immediate discontinuation of the drug. These cardiac dysfunctions were usually reversible after treatment stopped.
The review highlighted a particular drug combination associated with a higher risk of heart problems. According to the director of the Italian Cochrane Center, “Some of the earlier trials combined Herceptin with a class of drugs called anthracyclines, which is a combination not recommended in patients with metastatic breast cancer.”
- Balduzzi S, Mantarro S, Guarneri V, et al. Trastuzumab-containing regimens for metastatic breast cancer. Cochrane Database Syst. Rev. 2014. Epub ahead of print. June 12, 2014. Available at: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD006242.pub2/abstract. Accessed June 23, 2014.