Bone mineral density and nutrition in long-term survivors of childhood brain tumors.

BACKGROUND AND AIMS: Childhood cancer survivors are at risk of unwanted late effects. The primary aim of this study was to assess bone mineral density Z-scores (BMDz) in long-term survivors of childhood medulloblastoma (MB) or central nervous system supratentorial primitive neuroectodermal tumor (CNS-PNET). Secondary aims were to describe nutrient intake, vitamin D status, physical activity and explore potential risk factors for decreased BMDz.

METHODS

All MB and CNS-PNET survivors treated at Oslo University Hospital from 1974 to 2013 were invited to participate in a cross-sectional study. Dual-energy x-ray absorptiometry (Lunar Prodigy) assessed BMDz lumbar spine, BMDz total body, and lean body mass. Decreased BMDz was defined as a combination of low BMDz -1 to -1.99 and very low BMDz ≤-2. Lean body mass index (LMI) was calculated by dividing lean body mass by the squared height. Nutrient intake was assessed by a 3-day food record. Serum 25(OH)D was analyzed. Physical activity was reported by a questionnaire. Descriptive statistics and multivariable Cox regression analyses were applied.

RESULTS

Fifty survivors with a median age of 25.5 years (5.5-51.9) and a median follow-up time of 19.5 years (3.2-40.5) were included. Mean BMDz lumbar spine was -0.8 (SD 1.1, 95% CI: -1.1 to -0.4), and BMDz total body was -0.6 (SD 1.1, 95% CI: -0.9 to -0.3). Decreased BMDz was detected in 48% of the lumbar spine and 34% of the total body measurements. In all, 62% had low calcium, and 69% had low vitamin D intake. 26% of participants had serum 25(OH)D < 50 nmol/L, and 62% reported an inactive lifestyle. Male sex, higher age at diagnosis, and lower LMI were potential risk factors for decreased BMDz.

CONCLUSIONS

Long-term survivors of childhood MB and CNS-PNET had decreased BMDz, and risk factors were male sex, higher age at diagnosis, and lower LMI. Inadequate calcium and vitamin D intake, an inactive lifestyle, and a high prevalence of 25(OH)D ≤ 50 nmol/L were detected.