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 survivors, follow up studies are important. We have performed a retrospective analysis of growth for 49 children, who had undergone treatment with cyclophosphamide and TBI before BMT. Of these patients 26 received single fraction (SF) TBI as a dose of 900-1000 cGy, whereas 23 received 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. Half of the patients in the SF-TBI group, and 9 in the FF-TBI group had received low-dose cranial irradiation prior to TBI. In all groups a decrease in height SDS was observed. By evaluating the major factors leading to growth impairment the influence of cranial irradiation, which was 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 group with a mean height SDS of -0.9 (+/- SD 0.9) compared to a mean height SDS -0.22 (1.02) in the FF group (P < 0.05). Measurement of segmental proportions showed a significant difference in SDS for sitting height in comparison to SDS for subischial leg length, irrespective of the TBI regimen. This was already evident 1 year after TBI and decreased during the following years. Twenty four of the patients (17 in the single 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 affected in children after BMT, especially if SF-TBI is administered. Decreased growth rates were also observed after FF-TBI, but to a lesser degree, despite the higher total dose of irradiation.