ESPE Abstracts

Background: Childhood haematopoietic stem cell transplantation and total body irradiation (HSCT/TBI) survivors have multiple risk factors for reduced bone mineral density (BMD) and poor growth. Reduced z-scores from dual energy x-Ray absorptiometry (DEXA) have been reported, but are unreliable in patients with short stature/abnormal body composition.

Objective: To investigate the influence of HSCT/TBI on size-corrected BMD in childhood leukaemia survivors.

Method: Post-pubertal age- and gender-matched leukaemia survivors treated with HSCT/TBI (10–14.4 Gy) (n=21, 11 males, aged 21 (16.1–26.1)) at mean aged 9.3 (1.0–10.8) years were compared with patients treated with chemotherapy-only (n=30, 12 males, aged 21.5 (16.2–26) years) at (7.0 (1.6–18.0) years). Patients on long-term steroids were excluded. All had had endocrine evaluations and were on replacement hormones where appropriate. Assessments: height, weight, DEXA scanning (Lunar prodigy® fan beam) (BMD-z-scores, bone mineral content (BMC), bone area (BA) & width) and vitamin D levels. BMD was corrected for size as bone mineral apparent density (BMAD): Total-BMAD (BMD_T)=BMC/total body BA₂/height; Lumbar spine-BMD (BMAD_L2-4)=BMD_L2-4 x (4/(π×width)).

Analysis: student’s t-tests and Pearson’s correlations (5% significance).

Results: HSCT/TBI survivors had lower total-BMD z-scores (−0.74 vs 0.19, P=0.012), but were lighter (P<0.001) and shorter (P<0.001) than chemotherapy only patients. Total-BMD correlated positively with height-SDS, weight-SDS, fat and lean masses (all P<0.001). Size corrected BMD showed no mean (SD) differences between HSCT and chemotherapy-only patients: BMD_T (0.089 (0.008) vs 0.086 (0.007), P=0.13); BMD_L2-4 (0.38 (0.057) vs 0.37 (0.056), P=0.33). There were no relationships between BMAD_T or BMDL_2-4 with age at or time from primary diagnosis in both groups; or with age at and time from HSCT/TBI in HSCT/TBI group. The HSCT/TBI group showed no differences in BMAD_T or BMD_L2-4 in HSCT/TBI patients treated < or >8 years, and no relationships between BMAD_T or BMD_L2-4 with serum Vitamin D(p=0.13,p=0.21) or presence of endocrine disorders (growth hormone deficiency (P=0.16, P=0.46), hypothyroidism (P=0.53, P=0.58), gonadal failure (P=0.33, P=0.43)).

Conclusions: Size of patient must be taken into account to avoid over diagnosis of osteopenia when assessing BMD in cancer survivors. Treatment effects on peak bone mass in survivors need further evaluation.

Funding: The work was supported by the IPSEN clinical research fellowship, BSPED research Award, David Telling Research funds and Peel Medical research award.