January 1, 2005 — Studying childhood cancer patients who have suffered tissue and organ damage from chemotherapy treatments, researchers have found that growth hormones can reverse damage to the heart. Before the children started growth-hormone treatment their heart walls were very thin. Within weeks of starting it, the walls became thicker and their heart mass eventually became much closer to normal.
MIAMI--Childhood cancer survivors are living longer. Great improvements in treatments are to thank, but many of these drugs cause weakened hearts and make survivors more likely to die of cardiovascular disease.
At 5'7", 16-year-old Erik Aguirre's is a natural on the court. But when he was 3, mom Kathy didn't think Erik would live to ever dribble a ball. He was diagnosed with several medical problems, including a rare and fatal type of cancer. "I just couldn't believe that was happening to Erik," Kathy Crisci, Erik's mom, says.
Surgery, radiation and chemo saved Erik, but the cancer drugs made him, like many survivors deficient of growth hormone. It's a substance our bodies naturally produce. Growth hormone injections have helped Erik and other patients develop more normally. Now, results from a 10-year study of cancer survivors show it's also helping their hearts.
Certain chemo drugs destroy heart muscle cells -- making kids' hearts too small. Steven Lipshultz, from the University of Miami School of Medicine in Fla., says, "You are, in essence, creating a heart-attack-type model in a 4-year-old."
Pediatric cardiologists have found growth hormone is the first therapy shown to reverse that damage. Before kids started treatment, their heart walls were very thin. Within weeks of starting it, the walls became thicker, and their heart mass eventually became much closer to normal.
Erik's been cancer-free for 13 years and is now a big kid with an even bigger heart.
When kids in the study were taken off growth hormone, their heart muscle was reduced to what it had been before. The findings may be applied to help the millions of other people lacking heart muscle and die prematurely of cardiovascular disease.
BACKGROUND: Growth hormone replacement therapy can improve the growth of the hearts of children that are too small for the size of their bodies, according to a new long-term study published in the leading child health journal Pediatrics. This is good news for the thousands of childhood cancer survivors who often must undergo treatment that can drastically reduce the size of their hearts.
THE PROBLEM: Children with lung cancer are often treated with a family of chemotherapy drugs called anthracyclines. As a result, they often suffer from a reduced and insufficient amount of heart muscle, which in turn can lead to heart failure later on in life.
ABOUT THE STUDY: Researchers at the University of Miami School of Medicine examined cardiac findings for survivors of childhood cancer who were treated with anthracyclines. They found that those who received growth hormone replacement therapy experienced more normalization of wall thickness of the left ventricle -- the main pumping chamber of the heart -- than those who did not receive the therapy. The results suggest that long-term survivors of childhood cancers like leukemia suffer from a growth hormone deficiency.
WHAT ARE GROWTH HORMONES: Growth hormones are produced by the pituitary gland, which can be found at the base of the brain and controls most of the hormones in the body. Prior to puberty, growth hormone stimulates the growth of long bones; in adults, it affects the growth of organs and other tissues. It is sometimes taken illegally by athletes because it helps muscles to grow. Deficiencies in growth hormone are often seen in the elderly; in children, such a deficiency can cut growth rates in half, leading to dwarfism.
ABOUT CHEMOTHERAPY: Chemotherapy is a treatment for cancer, in which certain drugs (poisonous to cancer cells) are injected into the blood to kill cancer cells or to stop them from spreading. They can travel around the body and attack cancer cells wherever they find them, so chemotherapy is used when cancers have spread beyond one region of the body. One of the earliest chemotherapy drugs was produced from mustard gas, used as a chemical weapon during World War I.
Note: This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.
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