Risk factors for low bone mineral density (BMD) in pediatric sarcoma survivors

Abstract

9059 Background: The incidence of and risk factors for low BMD in patients treated for sarcoma in childhood is unknown. Methods: Retrospective medical record review of 99 patients with pediatric sarcoma diagnosed between 12/82 and 2/03 who had undergone QCT evaluation more than 1 year after completion of treatment. Low BMD was defined as >1.5 standard deviations below the mean. A Z-test was used to assess whether BMD was lower in our patient population than in the normal reference population. Logistic regression was used to examine factors predictive of low BMD. Risk factors analyzed included demographic variables, tumor features, treatment exposures, endocrine/renal dysfunction, and health habits. Results: Twenty-six of the 99 sarcoma survivors (26%) had low BMD. The mean (−0.8) and median (−0.75) QCT Z-scores were significantly lower than those of the normal reference population (mean and median = 0, p<0.0001). Factors associated with lower BMD included young age at sarcoma diagnosis (p=0.044) or at QCT measurement (p=0.001), greater weight at diagnosis (p=0.045), non-lower extremity tumor site (p=0.023), higher cumulative cyclophosphamide dose (p=0.007), smaller size at QCT measurement [height (p=0.018), weight (p=0.012)], and low serum creatinine [at diagnosis (p=0.033), at QCT measurement (p=0.014)]. Gender, race, ifosfamide/methotrexate/etoposide exposure, radiotherapy, endocrinopathy, and health habits were not predictive of low BMD. Conclusions: Survivors of childhood sarcoma are at high risk for low BMD. Risk factors include young age, non-lower extremity tumor site, and high cumulative cyclophosphamide exposure. Prospective studies are needed to confirm these risk factors, and to guide implementation of effective screening guidelines and therapeutic measures. No significant financial relationships to disclose.