Breast cancer 'wonder drug' Herceptin carries a risk for heart problems

Aug 15 2006

According to the latest research breast cancer wonder drug Herceptin puts some women at risk of heart problems.

In a new study researchers in the U.S. have found that Herceptin could cause harm to women with advanced breast cancer.

According to the American researchers, 28 per cent of patients who used the drug for at least a year suffered cardiac problems but they believe that risk is an "acceptable" one as the majority of heart damage could be reversed with treatment.

Herceptin, which is also known as trastuzumab, works by targeting the HER2 protein, which can fuel growth of breast tumours in women with HER2 positive breast cancer, which accounts for about 25 per cent of all breast cancer cases.

The drug has radically changed the prognosis for women with this type of breast cancer, especially when used in combination with chemotherapy and is now standard therapy for those with HER2-positive metastatic breast cancer.

It was already known that the drug weakened the heart muscle and is therefore not recommended for those with heart trouble and drug rationing bodies, gave that advice when granting approval for the drug.

The drug should not apparently be given to those at risk of heart failure and patients should undergo regular assessments.

In the UK the drug is licensed both early and advanced breast cancer and costs £21,000 for a years course.

Earlier clinical trials that tested Herceptin in combination with chemotherapy found that between 10 and 26 per cent of patients experienced cardiac problems and the Food and Drug Administration in the U.S. last year warned that Herceptin could cause congestive heart failure, leading to an inability to pump enough blood throughout the body.

In this latest study of 173 patients, 28 per cent of those treated with Herceptin were found to have experienced a "cardiac event" after a follow-up at 32 months.

The majority of these patients experienced the problems while being treated with Herceptin alone, after prior combined Herceptin and chemotherapy treatment.

The other 18 were being treated with a combination of Herceptin and chemotherapy. There was one cardiac-related death.

The study found that when patients stopped using Herceptin and were treated with heart drugs such as beta-blockers, their heart function improved and after the damage was repaired they were able to resume Herceptin treatment.

Dr. Francisco Esteva, senior author of the paper and an associate professor of medicine at M.D. Anderson Cancer Center in Houston, Texas, says Herceptin substantially prolongs survival, and while there was substantial cardiac toxicity, the side effect can be successfully treated.

The researchers do point out that most of the patients had prior treatment with chemotherapy drugs known to affect the heart, and some had other illnesses, such as diabetes, that can affect cardiac function.

In another study by researchers at the University of Pennsylvania it has been found that women with early stage breast cancer who received radiation on the left side of the chest were more likely to develop heart disease over the next 20 years than women who received radiation on the right side of the chest.

However the women who received left-sided radiation did not appear to have an increased risk of death from heart-related problems.

The University of Pennsylvania researchers compared the incidence of heart disease in 477 women who had had early stage breast cancer on the right side and 484 women who had had early stage breast cancer on the left side.

All the women had been treated with current radiation techniques between 1977 and 1994 and were followed for a median of 12 years.

At 20 years, 6.4 percent of patients with left-sided cancer had died from heart-related problems, versus 3.6 percent of those with right-sided cancer.

However experts say because radiation is continually becoming more focused, and the risk is likely to be reduced even further in the future.

Experts advise women to reduce and preferably eliminate other modifiable risk factors for heart disease such as high blood pressure, obesity and smoking.