GROWTH FOLLOWING SINGLE FRACTION AND FRACTIONATED TOTAL-BODY IRRADIATION FOR BONE-MARROW TRANSPLANTATION

Total body irradiation (TBI) is used as a preparative regimen prior to bone marrow transplantation (BMT). Since there are more long-term sur vivors, follow up studies are important. We have performed a retrospec tive analysis of growth for 49 children, who had undergone treatment w ith cyclophosphamide and TBI before BMT. Of these patients 26 received single fraction (SF) TBI as a dose of 900-1000 cGy, whereas 23 receiv ed fractionated (FF) TBI as a total dose of either 1200 cGy divided in six fractions or 1440 cGy divided in eight fractions over 3 days. Hal f of the patients in the SF-TBI group, and 9 in the FF-TBI group had r eceived low-dose cranial irradiation prior to TBI. In all groups a dec rease in height SDS was observed. By evaluating the major factors lead ing to growth impairment the influence of cranial irradiation, which w as demonstrable in the 1st year after TBI, could not be shown after 3 years. At this time growth was significantly more impaired in the SF g roup with a mean height SDS of -0.9 (+/- SD 0.9) compared to a mean he ight SDS -0.22 (1.02) in the FF group (P < 0.05). Measurement of segme ntal proportions showed a significant difference in SDS for sitting he ight in comparison to SDS for subischial leg length, irrespective of t he TBI regimen. This was already evident 1 year after TBI and decrease d during the following years. Twenty four of the patients (17 in the s ingle fraction and 7 in the fractionated TBI group) were treated with growth hormone, but demonstrated an inappropriate response with absent catch-up growth in their legs. In conclusion, growth is seriously aff ected in children after BMT, especially if SF-TBI is administered. Dec reased growth rates were also observed after FF-TBI, but to a lesser d egree, despite the higher total dose of irradiation.