Canadian cardiology team clears the way for lifesaving breast cancer treatment

October 26, 2009

A team of Canadian cardiologists, in collaboration with oncologists, are playing an important role in the war against breast cancer Dr. Michael McDonald told the Canadian Cardiovascular Congress 2009, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

At issue is how to use a highly effective drug therapy for early-stage breast cancer while maintaining the cardiovascular health of the patient. The drug - trastuzumab (herceptin) - inhibits cancer cell survival. Herceptin is prescribed as an adjuvant to other standard chemotherapy treatments.

Unfortunately, some women will develop serious heart complications as a result of herceptin-based treatment.

"These are women with no previous heart problems," says Dr. McDonald, a cardiologist.

In a worst case scenario, thousands of women could be denied a potentially life-saving therapy.

Thanks to a study by Dr. McDonald and colleagues from the Heart Function Clinic at Toronto General Hospital, there is hope for these women. They found that the affected patients can be taken off the medication and treated for the heart condition, allowing them to resume the cancer treatment unaffected.

"Approximately 25 per cent of breast cancer patients will be candidates for herceptin treatment. Of that number, approximately four to 10 per cent will develop a serious heart condition which may result in congestive heart failure, forcing them to stop their treatment," he says.

These patients develop a decline in their heart function - or ejection fraction - which puts them at risk for congestive heart failure.

The team examined 18 consecutive breast cancer patients, treated with herceptin, whose ejection fractions had dropped by at least 10 per cent or who were showing signs of heart failure. Following diagnosis of the heart complications, herceptin treatment was suspended in 13 patients while heart failure treatment with ACE inhibitors and/or beta blockers was initiated.

"After three months of follow-up, the cardiac complications had begun to improve and almost all patients had a near normalization of ejection fraction," says Dr. McDonald.

"Our study shows herceptin-related toxicity is largely reversible," he says. "A systematic, guideline-based approach to management including referral to a cardiology centre, temporary cessation of herceptin if necessary, and judicious use of heart failure medications can lead to a successful outcome for these patients."

But the news gets even better.

"We tested 14 of the 18 patients who were put back on herceptin and they were all able to complete the course of treatment," Dr. McDonald told the meeting.

The million dollar question is: does herceptin cause lasting damage to the heart? With the development of newer cancer medications that act in a similar fashion to herceptin, understanding the effect of this therapy on the cardiovascular system and response to intervention is critically important.

"It requires cross-specialty teamwork but dealing with herceptin-related cardiac problems is a challenge that can be met," says Dr. McDonald.

Heart and Stroke Foundation spokesperson Dr. Beth Abramson agrees: "This is good news for Canadian women," she says. "Heart disease and cancer are the two leading causes of death for women in this country. Hopefully ongoing collaboration between physicians in these fields will reduce both of these serious health threats to Canadian women − and save lives."

Abramson says prevention of heart disease and breast cancer share similar strategies, including following a heart healthy low-fat diet, increased physical activity, smoking cessation, and maintaining a healthy body weight.

Source: Heart and Stroke Foundation of Canada