Bone Abstracts

Background and aim: Multifaceted risk factors impair bone mass in childhood cancer survivors. Aims of the study were to evaluate bone mass and it’s determinant and fracture prevalence in CBCS 2 (G+2) or 5 (G+5) years after off therapy (OT).

Methods: Seventy-three (G+2) and 87 (G+5) CBCS were evaluated at 12.9±4.2 and 14.9±4.4 yrs, respectively. Diagnoses were: astrocytic (G+2:n=25, G+5:n=24), embryonal (G+2:n=28, G+5:n=22), sellar region (G+2:n=13, G+5:n=10) tumors, germinomas (G+2:n=13, G+5:n=18), ependimomas (G+2:n=3, G+5:n=7). Growth hormone deficiency (GHD) was diagnosed in 38(G+2) and 67(G+5) pts, while hypogonadism (HH) in 23(G+2) and 34 (G+5) CBCS. Patients underwent height (cm, SDS), BMI (kg/m²,SDS), pubertal (Tanner) and DXA (Lunar Prodigy Advance,GE) measurements. BMD(g/cm², Z-score), BMC(g) were obtained at the lumbar spine (L1–L4=L) and the total body less head (TB); lumbar BMAD (g/cm³) was calculated; fat (FM%, Kg) and lean mass (LM, Kg) were obtained.

Results: G+2 and G+5 had comparable height (−0.5±1.3SDS), BMI (0.7±1.2SDS), FM (kg), LM (kg) and age at diagnosis (8.0±4.4yrs); G+2 showed a reduced LBMD and LBMC (P’s=0.008 and 0.03, respectively) and a higher FM% (P=0.04) compared to G+5 and a non-significant lower LBMDZ-score (−0.85±1.33 and −0.61±1.23), BMAD (0.135±0.021 and 0.154±0.090), TBBMDZ-score (−0.72±1.08 and −0.59±1.04). A LBMD<-2Z-score was present in 19.2% and 11.5% (G+2 vs G+5) and a TBBMD<-2Z-score in 11.5% and 12.0% (G+2 vs G+5). G+2GHD pts had a lower LBMDZ-score (P=0.008) and TBDMDZ-score (P=0.03) compared to G+5GHD pts; G+2HH pts had a lower LBMDZ-score compared to G+5HH (P=0.04). In multivariable analyses LBMDZ-score was inversely predicted by age at study and directly by height in G+2 (R2 0.37) and G+5 (R2 0.23) after correction for LM, FM, GHD, HH; TBBMDZ-score was additionally predicted by LM in G+2(R2 0.57) and by LM and FM in G+5 (R2 0.54). Seven% CBCS in G+2 (5/72) and 2.3% in G+5 (2/86) presented fractures.

Conclusions: Older, shorter, GHD and HH CBCS are at risk of decreased bone mass after 2 yrs OT; a low bone mass might persist after 5 yrs OT; however, the fracture prevalence remains low.

Disclosure: The authors declared no competing interests.