Specific subgroups of children who survive treatment for childhood malignancies have been shown to develop relative osteopenia following chemotherapy and are felt to be at risk for developing osteoporosis later in life due to their inability to reach peak bone mass during childhood. Based upon an earlier study in our department, the investigators reported conclusive evidence that approximately half of survivors of pediatric solid malignancies are at risk for these problems. However, the proportion of patients in our population that showed osteopenia/osteoporosis was lower than that in other similar cross-sectional studies in solid tumors such as osteosarcoma. The main difference between our report and the osteosarcoma study was duration of follow-up, with ours being shorter. Longer follow-up may prove that a larger proportion of our patients are affected. The purpose is to perform a longitudinal follow-up study of bone mineral density using dual-energy X-ray absorptiometry (DXA) in adult survivors of solid pediatric tumors that were previously studied as subjects in our original cross-sectional study. The primary hypothesis is that the proportion of pediatric solid cancer survivors with significantly lower bone mineral density (BMD) compared to established age group controls will be increased with the additional time that has elapsed since the original study despite the fact that the patients are young and would not normally be expected to have osteopenia/osteoporosis at this age.