A drug that prolongs the survival of women with breast cancer carries a higher risk of cardiac problems than expected, a new study has found.
The researchers say that 28% of women receiving the novel breast cancer drug Herceptin (trastuzumab) suffered cardiac problems as a result. The affected women had to stop taking the cancer drug temporarily while their heart problems were treated.But the good news is that these complications are easy to treat with standard heart drugs, and the researchers advise women to continue taking Herceptin to keep their cancer in check.”These long-term cardiac side effects of Herceptin can be managed, and the drug is safe to use,” says lead researcher Francisco Esteva, professor of oncology at the University of Texas M.D. Anderson Cancer Center in Houston, US. Herceptin halves the risk of cancers recurring in female patients prescribed the drug. It is an antibody which attacks the HER2 protein on cancer cells-a protein which makes cancers more aggressive. Around 30% of women with breast cancer have abnormally high levels of the HER2 and so can benefit from receiving the drug.Everyday settingPrevious studies found that heart problems typically afflicted between 10% and 26% of recipients, but the incidence varied widely depending which chemotherapeutic drugs the women received besides Herceptin. Also, the results came from carefully controlled clinical trials. Estevaâs study is the first to find out the situation in real clinics where women are receiving the drug in an everyday medical setting. His team followed 173 patients who had taken Herceptin for at least a year after undertaking chemotherapy to combat secondary cancers. After follow-ups averaging almost three years, 49 had suffered cardiac problems, 28% of the total. In 46, the problems were severe enough to threaten heart failure. In the other three, the heart was not pumping as soundly as it should. The women who had these side effects had to stop taking Herceptin for up to two months while their heart problems were treated.Standard practiceEsteva says the heart problems could be remedied using standard heart drugs such as beta-blockers and ACE inhibitors. These ease stress on the heart by reducing the volume of blood the heart has to expel with each beat. “They continue to receive the cardiac drugs, plus Herceptin,” says Esteva. Furthermore, he doubts whether the cardiac drugs would make Herceptin any less effective. Esteva and his colleagues recommend heart checks on all potential recipients of Herceptin, and monitoring to spot cardiac problems. This is already standard practice in many countries, including the UK. “This reassuring study shows that by stopping the drug in the women who have an adverse reaction, and successfully treating the heart problem, the Herceptin treatment can safely restart,” says John Toy, the medical director of Cancer Research UK. (Source: Journal of Clinical Oncology; August 10th 2006 (DOI: 10.1200/JCO.2005.04.9551).