WEDNESDAY, July 7, 2004 (HealthDayNews) -- Drug treatment appears to prevent the heart damage that is a major drawback of a medical miracle in childhood cancer, researchers report.
In 1970, 90 percent of children who were diagnosed with acute lymphoblastic leukemia (ALL), the leading cause of pediatric cancer, died within five years. Today, 90 percent of them are alive and apparently cured because of a multiple drug regimen that works wonders.
But as adults, many of those patients suffer from the heart damage caused by one of those drugs, doxorubicin. Many of them die of congestive heart failure or another condition resulting from that damage.
Now physicians at the University of Miami School of Medicine report that adding another drug, dexrazoxane, to cancer therapy prevents or reduces heart damage, as measured by blood levels of an enzyme called troponin T, without decreasing the effectiveness of the treatment.
That evidence is not completely satisfactory to Dr. Leontine C. M. Kremer, a pediatrician at the University of Amsterdam in The Netherlands and co-author of an editorial accompanying the report in the July 8 issue of the New England Journal of Medicine.
While there is "no question that dexrazoxane is cardioprotective," Kremer said, "more studies focused on the survival are needed." The implications of moderate elevations of troponin T are not clear, she added.
But the results of the study are so clear, said Dr. Steven E. Lipshultz, chairman of pediatrics at the University of Miami and lead author of the report, that the international committee that sets standards for treatment of ALL has recommended that dexrazoxane be part of the treatment.
The end results in terms of reduced heart disease and fewer deaths from cardiac conditions are not available yet, Lipshultz said, but that is because the children in the study have been followed for just a few years. The study began in 2001, so it will be a long time before the patients become adults, Lipshultz said. However, five-year measurements of heart damage will start to become available in the near future.
One point not to be overlooked is that dexrazoxane treatment did not interfere with what Lipshultz called "one of the greatest advances in pediatric medicine in the last 50 years," the transformation of ALL into a curable disease.
The trial was a double-blind study, with 101 children with ALL getting standard drug therapy and 105 getting dexrazoxane as well. Neither doctors nor patients knew who was getting the drug, to make sure that knowledge did not affect assessment of the results.
Those results were so effective, in terms of troponin T levels, that the committee overseeing the trial ended it early. And "we find that it is absolutely terrific as a surrogate marker of cardiac injury."
As a cardiologist, Lipshultz has been accustomed to treating surviving ALL patients for the heart conditions caused by the treatment that kept them alive. Now he can hope to be doing less of that.
"For these children, it has been one fatal [heart] illness after another," he said. "But this study is so exciting. It does suggest that there is an ability of this agent to really prevent the heart from being damaged initially. We are hoping to see less heart muscle dysfunction."
Learn about acute lymphoblastic leukemia and its treatment from the National Cancer Institute.