Changes in body mass index and prevalence of overweight in survivors of childhood acute lymphoblastic leukemia: Role of cranial irradiation

Background The risk factors responsible for an increased prevalence of obesity or overweight in survivors of acute lymphoblastic leukemia (ALL) remain controversial. We evaluated changes in body mass index (BMI) in a cohort of ALL survivors, all of whom have been followed until completion of linear growth. Procedure BMI (weight/height2) was used as an index of adiposity and was calculated at diagnosis, at the end of treatment, and at attainment of final height in a cohort of 126 (59 males) survivors of ALL. BMI was adjusted for age and sex by computing a BMI standard deviation score (SDS) or z score. The spectrum of therapies used included intrathecal chemotherapy given alone (n = 38) or combined with cranial irradiation (CRT; 18 Gy, n = 35; 24 Gy, n = 53) and exposure to prednisone at a low dose ( 9.4 gm, n = 30). Results Overall, mean ± SEM BMI-SDS increased significantly between diagnosis (−0.18 ± 0.08) and the end of therapy (0.41 ± 0.09, P < 0.01), with no significant change thereafter. For patients without CRT, mean BMI-SDS remained unchanged, whereas, for those so treated, mean BMI-SDS increased significantly between diagnosis and the completion of therapy (P < 0.001). The change in mean BMI-SDS was greater in the 24 Gy group vs. the 18 Gy CRT sample (P < 0.005). In a multivariate logistic regression model, CRT was an independent predictor of being overweight (BMI ≥85 percentile) at attainment of final height [odds ratio = 1.6 (95% confidence interval 1.0–23.1)]. The percentage of subjects who were overweight at attainment of final height was 10.5%, 40%, and 38% for subjects treated with no CRT, 18 Gy CRT, or 24 Gy CRT, respectively (P < 0.01). Conclusions Children with ALL given CRT develop increases in their BMI-SDS early on and during treatment and remain at significant risk for becoming overweight as young adults, a development that may increase their already heightened risk for various adverse health outcomes. Med. Pediatr. Oncol. 35:91–95, 2000. © 2000 Wiley-Liss, Inc.