Association of Muscle Strength and Bone Mineral Density in Adult Survivors of Childhood Acute Lymphoblastic Leukemia

Joyce ED, Nolan VG, Ness KK, Ferry RJ Jr, Robison LL, Pui C-H, Hudson MM, Kaste SC. Association of muscle strength and bone mineral density in adult survivors of childhood acute lymphoblastic leukemia. Arch Phys Med Rehabil 2011;92:873-9. Objectives: To investigate the association between bone mineral density (BMD) and muscle strength in survivors of childhood acute lymphoblastic leukemia (ALL), a population at increased risk for both decreased BMD and muscle strength from cancer and its treatment. Design: Cohort data from the St Jude Lifetime Cohort (SJLIFE) study. Setting: Department of Cancer Control at St Jude Children's Research Hospital. Participants: Subjects were adults enrolled in St Jude Lifetime Cohort study and treated for childhood ALL between 1962 and 1999. As part of a comprehensive evaluation, participants had dual energy x-ray absorptiometry (DEXA) scans and muscle strength testing. The participants consisted of 261 women and 232 men who were 20.4 to 49.8 years old (median, 35.7y), and 12.7 to 46.5 years from diagnosis of childhood ALL (median, 27.2y). Interventions: Not applicable. Main Outcome Measures: BMD was determined by DEXA scan. Muscle strength of upper and lower extremities was assessed with physical performance testing. Results: After adjusting for covariates, we found significant (P<0.005) associations between BMD and muscle strength in lower extremities (R-2 range, 0.33-0.40) and strong, significant associations in upper extremities (left-side R-2=0.558; right-side R-2=0.560). Conclusions: Muscle strength was associated with BMD in the extremities of long-term survivors of childhood ALL, a finding suggesting that muscle strengthening interventions may improve bone health in them.