Cancer expert dispels fears over risks of new drug

A STUDY suggesting that women who take a new ‘wonder drug’ to treat breast cancer are at a greater risk of developing cardiac problems than originally thought has been disputed by an Irish cancer expert.

The drug Herceptin, which offers fresh hope to women with early and advanced breast cancer, was approved for use in record time by the European Commission last May.

It took just 27 days for the commission to authorise the application for the drug because data on its effectiveness in treating early-stage HER2-positive breast cancer is so compelling.

Cancer specialist Professor John Crown said Irish oncologists agreed to prescribe the drug immediately after the data confirmed that it worked.

An estimated 25% of women with breast cancer will be given Herceptin, an antibody that works by attaching itself to HER2, a protein found on some breast cancer cells, and blocking its function, which is to instruct other cancer cells to grow.

Now a new American study published in the latest issue of the Journal of Clinical Oncology has found that 28% of women with advanced breast cancer who were taking the drug suffered cardiac problems after a follow-up at 32 months.

But the authors did note 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 also affect the heart.

The small-scale study, which involved 173 women with cancer that had spread beyond the breast, was conducted at the MD Anderson Cancer Centre in Heuston, Texas.

In 49 women, the heart lost some of its pumping ability. More than half had no symptoms but some felt short of breath. Most of the women recovered fully after treatment and could take the drug again but a few had lingering problems and one died from heart failure.

Prof Crown said he was involved in a study of 3,000 patients who were taking the drug for a year and the incidence of cardiac problems was between 2.1% and 1.7%, depending on the type of chemotherapy also being used to treat the disease.

“It has been known since the early days of Herceptin use that it had a small potential for causing cardiac toxicity. This is very occasionally severe,” he said.

“Because some chemotherapy drugs can also cause cardiac toxicity, great care must be exercised when combining chemotherapy and Herceptin,” he said.

Prof Crown said the research he was involved in found that the incidence of cardiac side effects, at 1.2%, was extremely small if Herceptin is given with chemotherapy drugs that do not cause heart damage.

He said Irish oncologists did not recommend giving Herceptin as the same time as cardiac-toxic drugs and patients were always routinely warned of the small risk of Herceptin cardiac damage.

* Those with concerns about breast cancer should contact the Action Breast Cancer helpline on 1800-309040. They can also visit www.cancer.ie/action.