Bone health in long-term survivors of acute lymphoblastic leukemia in children and ado-lecents. An assessment by peripheral quantitative computed tomography

Background – Loss of bone mineral is a common concomitant of the treatment of acute lymphoblastic leukemia (ALL) due mainly to chemotherapy, especially with corticosteroids. Osteopenia/osteoporosis may persist long into survivorship. Measurement of bone mineral density (BMD) by dual energy X-ray absorptiometry is limited to two-dimensionality and cannot distinguish trabecular from cortical bone. Methods – A sample of 74 subjects, more than 10 years from diagnosis, underwent peripheral quantitative computed tomography (pQCT) at metaphyseal (trabecular bone) and diaphyseal (cortical bone) sites in the radius and tibia. pQCT provides three-dimensional assessment of bone geometry, density and architecture. Results – Similarities of average values in multiple metrics with those in healthy subjects obscured deficits in both trabecular and cortical bone, as well as bone strength, revealed by Z scores using an ethnically comparable sample of healthy individuals. Connectivity, a measure of bone architecture and a surrogate measure of bone strength, was lower in females than males. Survivors of standard risk ALL had greater connectivity in and more compact trabecular bone than high risk survivors who had received more intensive osteotoxic chemotherapy. There were no statistically significant differences in any of the metrics at any of the sites between subjects who had or had not a history of fracture, cranial irradiation or use of a bisphosphonate. Conclusions – These long-term survivors of ALL have somehat compromised bone health, but data in comparable healthy populations are limited. Longitudinal studies in larger and more ethnically diverse cohorts will provide greater insight into bone health in this vulnerable population.