September 5, 2012 — Experts are warning that the breast cancer drug Herceptin (trastuzumab) may have a higher risk of cardiovascular injuries than previously thought. In a study published August 30 in the Journal of the National Cancer Institute, experts found that patients taking Herceptin had a four-fold increased risk of heart failure compared to people who did not take the medication.
The researchers found that people taking any anti-cancer drug in the anthracycline class (which includes Herceptin) had about the same risk of heart failure as other classes of cancer drugs. However, patients taking an anthracycline plus Herceptin had a seven-fold increased risk of heart failure.
Before this study, experts already knew that women who were treated with anthracycline drugs had a higher risk of cardiomyopathy (a type of degenerative heart muscle disease) and heart failure. These two cardiovascular diseases are often deadly. However, most of the studies concerning this risk excluded women older than 70 and those with other chronic diseases. Therefore, the studies do not give an accurate real-world picture of the risks faced by the general population.
The researchers analyzed data on 12,500 women who were diagnosed with invasive breast cancer from 1999 through 2007. The average age of the women in the study was 60 years old, and the follow-up time was between 2-7 years. The researchers tracked the patients’ type of cancer treatment and compared this to diagnoses for cardiovascular diseases.
The researchers concluded by advising that doctors monitor patients using these medications for heart problems. This may involve pre-treatment tests of heart function, and periodic testing during chemotherapy treatment. The researchers also warned, “The study suggests the long-term risk for heart failure may be higher in women treated in the community than in clinical trials, particularly women who are older and/or have [other diseases besides the cancer].”
Herceptin is an anti-cancer drug that was first approved in 1998. It is used as a treatment for 25-30% of women with a type of breast cancer that generates a protein called HER-2, which makes the cancer more aggressive.
The drug company Roche is currently conducting a study to determine whether patients treated with Herceptin for two years live longer than those treated with standard cancer therapy. Another French study is looking at the six-month risk-benefit profile of Herceptin.