[Leptin, body composition and bone mineralization in children after treatment for Wilms tumor]

Advances in diagnosis and improved methods of treatment have resulted in increasing number of long-term survivors in children with Wilms tumor. Growth and puberty are important for accumulation of bone mass; chemotherapy nad radiotherapy used in treatment for Wilms tumor can influence bone structure and physical development. Leptin plays an important role in metabolism of adipose tissue and bone mineralization. Considering that neoplasm and its treatment can affect normal development in childhood, we analysed the influence of antineoplastic treatment on bone mineralization and the correlations between serum leptin levels, body composition and bone mineral density in survivors of Wilms tumor. Twenty subjects (12 boys) treated for Wilms tumor at the mean age of 10.9 (range 3-20 years) participated in this study. Mean follow up period after discontinuation of therapy was 5.6 years (range 2 months - 13.5 years). Mean age of diagnosis was 3.9 years (range 1 month - 12.6 years). 18 patients received chemotherapy, 7 - additionally radiotherapy and 2 infants had only surgery treatment. We measured fat mass - FM, fat free mass - FFM, bone mineral density - BMD total and BMD spine using dual energy x-ray absorptiometry (DXA) and compared to the results obtained for healthy references (SD score). Leptin levels were measured with RIA method.

1. No difference was found in leptin levels, body mass index, FM, FFM, BMD total and spine in relation to sex. 2. Means of SDS BMI, FM, FFM, BMD and leptin were in the normal range for the age and sex matched controls. 3. We found the correlation between leptin level and BMI, FM, FFM and BMD total and spine, no correlation was found between SDS values. 4. We observed a positive correlation between SDS BMD and SDS BMI, FM, FFM, BMD spine. 5. BMI, FM and leptin levels were higher in children treated with radiotherapy and chemotherapy than in children treated with only chemotherapy. However, the SDS values were comparable with the healthy controls. 6. SDS BMD total was decreased in 5/20 subjects (25% of all studied patients) compared with healthy controls.

The results demonstrated the risk of osteopenia in the group of children treated for Wilms tumor and the necessity for long-term monitoring of bone mineralization.