1 out of 10 Women Taking Breast Cancer Drug Herceptin Experience Heart Issues

The breast cancer drug trastuzumba (Herceptin) has been found to cause heart issues in as many as one in 10 women taking the medication, according to a study published in the Journal of Clinical Oncology. While many of the cardiovascular problems are reversible following the end of treatment, some can be more dangerous than others.

The breast cancer drug Herceptin is used in breast cancers that tests positive for HER 2 (human epidermal growth factor receptor 2), which promotes the growth of cancerous cells. The drug works by killing the cells and boosting survival rates in patients, and is typically given to patients following primary breast cancer treatments, including chemotherapy, surgery and radiation, according to WebMD. 

However, certain heart issues can result from taking the medication, including congestive heart failure and the organ's decreased ability to pump blood out of the left ventricle.

To further test the side-effects of the medication, researchers followed over 5,000 women with early stage breast cancer for an average of eight years. They evaluated how often cardiac problems occurred, when they did, and if they disappeared after a certain time period.

Three different groups of women were followed, including about 1,700 participants in each of the three groups: one that did not get the medicine, another that took it for one year and another group that took it for two years. According to study researcher Dr. Brian Leyland-Jones, vice president of molecular and experimental medicine at Avera Cancer Institute in Sioux Falls, S.D., the current standard of care is typically one year.

Study results revealed that close to 10 percent of women in the two-year group had heart issues, including three cardiac deaths. While 5 percent of participants in the one-year group suffered from heart issues. Congestive heart failure occurred in less than 1 percent of both groups. Blood pumping issues occurred in about 7 percent of the two-year group and 4 percent of the one-year group.

However, researchers note that the low percentages reinforce a rather positive study conclusion.

"What this confirms is a very low incidence of cardiac events, even when you give two years of the drug, which is no longer practiced," Leyland-Jones said.