A drug that can reduce heart damage from chemotherapy in adults seems to have the same effect in children, researchers report in the New England Journal of Medicine (Vol. 351, No. 2: 145-153).

Because more than half of childhood cancer survivors have been treated with chemotherapy drugs that are known to cause heart damage, the finding could be an important step toward helping these children lead longer, healthier lives.

"Currently the 5-year survival rate of children diagnosed [with cancer] during the first 14 years of life is 77%, but the price they are paying for their survival is often late effects of their therapy," said lead author Steven Lipshultz, MD, chairman of pediatrics at the University of Miami School of Medicine.

Chemotherapy drugs known as anthracyclines can kill heart muscle along with cancer cells. Patients who get these drugs may develop congestive heart failure, improperly beating left ventricles, or heart arrhythmias that can cause sudden cardiac death. Despite these side effects, anthracyclines are widely used because they are among the most effective drugs for many types of cancer, including acute lymphoblastic leukemia (ALL), the most common form of cancer in children.

Lipshultz and colleagues studied 206 children newly diagnosed with high-risk ALL. Half were given standard chemotherapy with the anthracycline drug doxorubicin (Adriamycin). The other half received doxorubicin plus the drug dexrazoxane (Zinecard), which has been shown to protect adult hearts from some of the cardiac effects of doxorubicin.

Before, during, and after treatment, the researchers measured the children's blood levels of the protein troponin T. This protein is usually undetectable in blood when the heart is healthy, but levels rise when the heart is damaged.

Fifty percent of the children who received standard chemotherapy alone had elevated levels of troponin T, but just 21% of the children who had also received dexrazoxane showed this evidence of heart damage. About 32% of the children in the chemotherapy-alone group had extremely high levels of the protein, indicating more serious damage, compared to just 10% of the children who got the second drug.

After more than 2 years of follow-up, the leukemia was kept under control equally well in both groups; adding dexrazoxane did not appear to alter the effectiveness of the chemotherapy.

"These findings demonstrate that it is possible to decrease some of the chemotherapy's delayed toxic effects on the heart," said the study's senior author Stephen Sallan, MD, of the Dana-Farber Cancer Institute in Boston.

Although the results are promising, there are still unanswered questions about this therapy.

It will take longer-term follow-up of the children in this study to determine whether the differences in troponin T levels actually translate into fewer heart problems later, researchers say. Longer follow-up and larger studies will also be needed to ensure that the dexrazoxane really didn't lessen the effect of the chemotherapy. And researchers will need to experiment with different dosages and timing to find the best way to administer dexrazoxane to get the most benefit.

Sallan also noted that the heart damage only appeared to be reduced, not eliminated. Other research will be needed to find ways to limit or prevent this side effect of treatment.