Overview

Growth problems are a common side effect of treatment for childhood cancers. Problems with growth are caused by damage to the pituitary system, also known as the hormone system. Chemotherapy and radiation to the brain (cranial radiation) can damage the sensitive organs that comprise this system, resulting in lower than normal levels of essential hormones such as growth hormone and thyroid hormone. Early diagnosis and treatment with hormone replacement will help assure that survivors of childhood cancers reach their optimal height and healthy body weight.

What are growth problems?

Common growth problems include reduced height and/or metabolism problems that result in obesity and reduced lean muscle.

What causes growth problems?

A common cause of growth problems in survivors of childhood cancers is their past treatment for cancer. Chemotherapy and radiation can cause damage to the endocrine or hormone system, which is comprised of many organs that release hormones into the body, including the thyroid, pituitary, and adrenal gland. Hormones are chemical substances that control the activity of certain cells in the body. The most commonly known hormones are the sex hormones, estrogen and testosterone; however; there are many other hormones that serve a variety of functions in the body. For example, the pituitary gland in the brain releases growth hormone which stimulates growth in all parts of the body, and the thyroid gland in the neck releases thyroid hormone, which increases metabolism.

The cancer treatments that are most likely to damage the endocrine system are cranial radiation and chemotherapy. Chemotherapy with cranial radiation and chemotherapy alone are known to cause obesity even after patients treated for childhood ALL have attained their final height. Also, a lower than predicted final height occurs in patients treated with cranial radiation or the combination of chemotherapy and cranial radiation. [1]

What are the symptoms of damage to the endocrine system?

Long-term survivors of childhood cancer are likely to experience growth hormone deficiency resulting in: [2],[3],[4]

• Lower than predicted height.

• Obesity (increased fat mass).

• Reduced strength (reduced lean mass).

• Reduced exercise tolerance.

• Low bone density.

• Problems with progression of puberty.

• Infertility.

• Azoospermia in males (no sperm).

• Lower quality of life.

• Lower academic achievement.

What can be done to prevent growth problems?

Early diagnosis and treatment will help ensure that patients reach their optimum growth potential.[5] Also, the use of multiagent chemotherapy and lower radiation doses and volumes has decreased the long-term side effects of treatment for children with Hodgkin’s disease. These approaches, aimed at reducing the risk of long-term growth problems, are also being evaluated in children with ALL.[6]

How are growth problems treated?

Treatment for growth problems may consist of administration of the hormones that are deficient, such as growth hormone, thyroid hormone, or sex hormones. A common treatment for children that have undergone treatment for cancer is regular injections of human growth hormone to treat a deficiency of this naturally occurring hormone. Some children receive daily injections, while others receive injections several times a week. Treatment usually lasts several years, although results are often seen as soon as three to four months after the injections are started. The earlier the treatment for growth hormone deficiency is started, the better chance the child will have of attaining normal or near-normal adult height.

References

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