Research studies have shown that children who are long-term survivors of childhood leukemia may be at greater risk for early bone loss called osteoporosis. This bone loss may lead to a greater risk of broken bones and other spine and bone problems. However, researchers still do not know much about how frequently this long-term side effect may occur and how severe the problem is.

St. Jude Children's Research Hospital researchers want to determine the frequency and severity of this side effect. They are also studying whether taking calcium and Vitamin D supplements can help children at risk for osteoporosis and if certain factors can be identified -- such as age at diagnosis, cancer treatments, or family history -- that may increase the chances of having osteoporosis. Researchers will take an x-ray study called quantitative computed tomography (QCT) to measure bone mineral density (BMD). The BMD is a measure of bone strength. If a subject's BMD falls below the average, he/she will be assigned to one of two groups. Subjects will be randomly assigned (like tossing a coin) to receive calcium and vitamin D pills. The other half will receive placebo pills that look like the calcium and vitamin D pills.