Early Bone Mineral Density Changes and Endocrinal Dysfunction in Childhood Brain Tumor Patients: A Prospective Study

Abstract

Reduced bone mineral density (BMD) and hormonal dysfunction are considered as a late effect of cranial radiation (RT). Only few studies have reported the occurrence of these problems soon after the diagnosis of brain tumor or RT initiation, emphasizing that these are not necessarily the late effects of RT. Thus, we conducted the study to analyze the incidence of low BMD and hormonal dysfunction prior to or within 6 months of RT (early change) in children with brain tumors. The study was conducted as a part of intramural funding program at a tertiary care center in India. Childhood and adolescent brain tumor patients were advised for dual energy X-ray absorptiometry scan (DXA) and hormonal evaluation prior to RT. In some patients, first DXA was done within 6 months of RT due to logistics. To see the effect of radiation, we have planned to repeat hormonal evaluation after 6 and 12 months and DXA after 12 months of RT. Twenty-five patients were analyzed. Median age at diagnosis was 11 years with a male to female ratio of 5.2:1. Medulloblastoma was the commonest diagnosis (n = 12), followed by glioma (n = 8), pineal tumors (n = 3) and ependymoma (n = 2). Nineteen and six patients underwent DXA before RT and within 6 months of RT respectively. For BMD assessment, Z score was calculated at hip and lumbar spine. BMD was defined as low (Z score = -1 to-1.99), very low (Z score = -2 to -2.5) and secondary osteoporosis (Z score ≤ -2.5). Median Z score at femur neck and spine was -2 and -1.9 respectively. Overall; 6, 3 and 9 patients had normal, low and very low BMD respectively. Seven patients had secondary osteoporosis (Table 1). Two patients with secondary osteoporosis had low vitamin D levels. None of the patient had compression fracture. On statistical analysis, no correlation was found between BMD changes and age, sex and site of the tumor. Pre RT endocrinal assessment (N = 25) was done by tanner staging and serum hormonal levels (GH, T3/T4/TSH, ACTH, cortisol and prolactin). Gonadal hormonal assessment was done in children with early or delayed puberty. Three patients were found to have endocrinal abnormality before RT (precautious puberty, central hypothyroidism and low sex hormones in 1 patient each). Follow up DXA and hormonal evaluation are awaited to see the effect of RT. The index study is one of the very few studies evaluating the early changes in BMD and hormonal dysfunction soon after brain tumor diagnosis or within 6 months of RT. We observed that a significant proportion of children had reduced BMD and hormonal dysfunction before RT, highlighting the importance of early assessment and referral to the specialist for better quality of life. Table 1: BMD and endocrinal dysfunction before or within 6 months of RT.