Body composition of long-term survivors of acute lymphoblastic leukaemia.

Background: Long-term quality of life is of growing importance in children previously treated for malignancy. Obesity defined indirectly from indices of height and weight, has been described in long-term survivors of acute lymphoblastic leukaemia (ALL) and hypothesised to be a consequence of previous cranial irradiation.

Procedure: In this study, measures of whole and regional body composition using skinfold and dual energy X-ray absorptiometry (DEXA) measurements have been made in 35 long-term survivors of ALL who had received cranial irradiation and chemotherapy. To assess the influence of cranial irradiation, results were compared with those obtained in 21 children treated for other malignancies, who received chemotherapy alone and with 31 healthy sibling controls.

Results: Girls treated for ALL were significantly fatter than those treated for other malignancies or healthy control siblings whether measured by skinfold thickness (median (range) 37.4% (17.9-41.3) vs. 24.6% (19.1-35.0) and 28.8% (19.6-43.1), respectively, P<0.01) or DEXA (33.5% (20.5-42.8) vs. 25.5% (16.5-31.0) and 24.5% (18.8-53.6), respectively, P<0.01). Boys treated for ALL were not significantly fatter than boys in the other two groups. Measures of whole body percent fat derived from DEXA were persistently less than those derived from skinfold measurements with a mean (95% CI) difference of 2.4% (1.7-3.1, P<0.001) for all groups combined. In ALL survivors, using regression equations for skinfold thicknesses derived from controls with DEXA as the 'gold standard' method, fat mass was significantly overestimated.

Conclusion: Female survivors of ALL are significantly fatter than those of other malignancies and healthy sibling controls. Caution should be observed in the application of published equations, derived from the normal population, for the calculation of body composition in children treated for ALL. The mechanism of onset of obesity remains unclear, but is probably multifactorial and related to previous cranial irradiation.