Breast Cancer Drug Herceptin Linked to Heart Risks
But most of these effects reverse after women finish treatment, experts say
Three cardiac deaths occurred in the two-year group, none occurred in the one-year treatment group, and two deaths occurred in the no-drug group, according to the study.
Congestive heart failure occurred in less than 1 percent of both drug groups. "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.
Blood pumping problems occurred in about 7 percent of the two-year group and 4 percent of the one-year group.
The study authors don't know for sure why the drug is associated with heart issues, but they noted that HER2 is linked with the regulation of cell growth and survival in the heart. Using the drug may take away those heart protective effects.
After stopping the drug, the blood pumping problems resolved in more than 87 percent of the two-year group and more than 81 percent of the one-year group.
The new findings reaffirm previous research with shorter follow-up times, said Dr. Joanne Mortimer, director of Women's Cancer Programs and co-director of the Breast Cancer Program at City of Hope Cancer Center in Duarte, Calif. She reviewed the findings but was not involved in the study.
The new study reaffirms that the heart problems linked with the drug don't increase with time, she said, "and that's what is important."
"There's no question this is a really important drug," Mortimer said, as previous studies have shown trastuzumab to improve survival from this more aggressive form of breast cancer.
Doctors know that women with a history of high blood pressure and those over 65 are at higher risk of heart problems while on the drug, she said.
Women should have a cardiac assessment before starting trastuzumab, Leyland-Jones said, and should have cardiac monitoring while they are taking it so that any cardiac problems related to the drug can be found and treated early.