Currently, 5 to 25% of children with ALL are classified to high risk groups and are treated

with 18 Gy CRT. In the US approximately 25,000 to 30,000 long-term survivors of childhood ALL have a history of exposure to CRT. This represents 8 to 10% of all pediatric cancer survivors [21]. As radiotherapy is now spared to most patients with ALL and the doses applied in the high risk patients are lower (18 Gy), the clinical features of ALL survivors, that were common in the past, including short R428 stature and obesity, are now less frequently seen. In our cohort CRT was used in 38% of patients, and the median dose was 18.2 Gy. Ross et al. suspected, that polymorphism of leptin receptor might influence obesity in female survivors of childhood ALL. Female survivors with BMI > 25 were more likely to be homozygous for the 223R allele (Arg/Arg) than those with BMI <25. Moreover, among females treated with CRT (≥20Gy), the patients who were homozygous for the 223R allele (Arg/Arg) had six times higher risk of BMI >25 than those with 223QQ or 223QR genotypes (Gln/Gln or Gln/Arg)[22]. In our study we have determined the

polymorphisms of leptin and leptin receptor genes in pediatric population. Contrary to the results presented by Estrogen antagonist Ross et al. we have not found any correlation of the selected polymorphisms of leptin and leptin receptor genes with overweight and the intensity of chemotherapy and/or CRT. We have not identified any oher studies revealing the influence of the polymorphisms of both leptin and leptin receptor genes on the metabolism of adipose tissue in survivors of childhood ALL. In our cohort we found highly significant increase in leptin levels in overweight patients in the entire study group and in gender subgroups. Negative correlation was found between leptin and soluble leptin receptor levels (in the entire study group and in male patients) suggesting negative feedback between those peptides. The same relationship was observed

by other authors in children with Anacetrapib uncomplicated obesity [12]. Significant increase of leptin levels in all patients treated with CRT and in female patients treated with CRT was observed. It was consistent with previous reports saying, that CRT causes accumulation of adipose tissue and that female patients are more affected than male patients [3, 23, 24]. As the soluble leptin receptor levels decrease, the clearance of leptin from circulation should be faster and its levels (and bioavailability) should be lower [10]. This is in discrepancy with higher incidence of overweight status in such patients. Because the plasma levels of soluble leptin receptors correlate with the density of leptin receptors on cell membranes [12], it is possible that after CRT involving the area of hypothalamus such density might decrease, thus reducing the inhibitory effect of the peripheral signal informing of the accumulation of body stores of energy.