Protecting Children from Human Growth Hormone Risks
Human Growth Hormone
Since 1959, human growth hormone has been used to promote growth in children who do not produce growth hormone naturally or who have one of several conditions that impair growth. Because the hormone was derived from human cadavers, it was in short supply.
In 1985, however, the availability of synthetic growth hormone created an essentially unlimited hormone supply. Drug manufacturers began to promote the use of the hormone for healthy children whose bodies produce growth hormone, but who are shorter than most children their age. In 2003, the U.S. Food and Drug Administration approved the use of growth hormone for children who are in the bottom 1 percent for height for their age. Children treated are to be those with a predicted adult height below 5 feet 3 inches (boys) and 4 feet 11 inches (girls).
Hundreds of thousands of children have been treated, typically with daily subcutaneous injections that continue until adult height is reached. The cost is approximately $40,000 per year. Typically, a child gains approximately 2 inches of height, compared to pretreatment predictions.
Over the short run, side effects are minor, including excessive leanness, increased blood glucose, and joint pains. Treated children do not appear to be at increased risk for leukemia, the commonest form of childhood cancer.
For long-term safety, a very different situation emerges. Very little long-term research has been conducted, and the information that is available is worrisome.
Growth hormone increases the concentration of insulin-like growth factor (IGF-I) in the bloodstream. IGF-I encourages the multiplication of cells in the body and, in several studies, is linked with risk of cancer of the breast, prostate, and other sites.
In 2002, a team of English researchers reported the results of the only long-term study of people treated with cadaveric growth hormone. The 1,849 participants had been treated between 1959 and 1985 and were followed until 1995 to see if any developed cancer, and to 2000 for cancer deaths.
At that time, few participants would have been older than age 45 and 50, respectively. Even so, 12 participants had been diagnosed with cancer, and 10 had died of it. Although these numbers are low, these cases are worrisome because they occurred in relatively young people, for whom the usual risk of these cancers would be extremely low. The study showed that, overall, growth-hormone-treated individuals are at higher-than-normal risk of both colorectal cancer and Hodgkin’s disease.
More reason for concern comes from individuals with acromegaly, a condition in which the body produces extra growth hormone. Their risk of colorectal cancer is much higher than the general population. They also have increased risk of joint pains and carpal tunnel syndrome.
In addition, it has long been known that tall individuals are at higher risk for cancer of the breast, ovary, uterus, prostate, colon and rectum. The presumption is that the hormones that led to increased height, in turn, also increase cancer risk.
Some measure of comfort may come from the fact that synthetic hormone is commonly given smaller daily doses, rather than large three-times-per-week doses, which was routine for cadaveric hormone, and doses are based on body size, allowing physicians to prescribe smaller amounts. Nonetheless, the amount given still commonly exceeds the amount that would be normal for the child.
Some research has shown that children whose bodies are somewhat low in growth hormone actually have a low risk of cancer. Shorter men have less risk of prostate cancer and may have greater longevity, compared with taller men. Treating them with the hormone may elevate them to the “normal” level of cancer risk.
Healthy short children have no medical problem. The “problem” growth hormone seeks to treat is the presumed stigma of being short. However, studies show that the treatment has no effect on social adjustment or self-esteem.
Parents of children who have received growth hormone treatments can reduce their children’s risk of cancer. Because one of the biggest risks is colon cancer, parents can:
- stop the hormone treatments;
- encourage their child to have colonoscopies in adulthood to remove precancerous polyps; and
- avoid meat, and have plenty of fiber-rich vegetables, fruits, beans, and grains.
These steps will reduce the risk of colon cancer.