Background: Hypothalamic obesity has major impact on prognosis and quality of life (QoL) in childhood craniopharyngioma. Patients and methods: For this study, 120 patients were prospectively recruited during 2001 and 2007 and evaluated after 3 years of follow-up (KRANIOPHARYNGEOM 2000). Body mass index (BMI) and QoL at diagnosis and 36 months after diagnosis were analysed based on the reference assessment of tumour localisation and post-surgical hypothalamic lesions. Treatment was analysed based on the neurosurgical strategy of 50 participating neurosurgical centres, the centre size based on the patient load. Results: BMI SDS at diagnosis was similar in patients with or without hypothalamic involvement. Surgical lesions of anterior and posterior hypothalamic areas were associated with higher increase in BMI SDS during 36 months post-diagnosis compared with patients without or only anterior lesion (C1.8 BMISD, PZ0.033, C2.1 BMISD; PZ0.011), negative impact on QoL in patients with posterior hypothalamic lesions. Surgical strategies varied among the 50 neurosurgical centres (three largesized, 24 middle-sized and 23 small-sized centres). Patients treated in small-sized centres presented with a higher rate of hypothalamic involvement compared with those treated in the middle-and largesized centres. Treatment in large-sized centres was less radical, and the rates of complete resection and hypothalamic surgical lesions were lower in large-sized centres than those of the middle-and smallsized centres. However, a multivariable analysis showed that pre-operative hypothalamic involvement was the only independent risk factor for severe obesity (PZ0.002). Conclusions: Radical neurosurgical strategies leading to posterior hypothalamic lesions are not recommended due to the potential to exacerbate hypothalamic obesity and impaired QoL. Treatment should be confined to experienced multidisciplinary teams.

Hypothalamic tumor involvement and familial disposition for obesity are risk factors for the development of severe obesity in patients with craniopharyngioma. As weight gain starts early after diagnosis and severe obesity causes a reduction in QoL, early therapeutic efforts should be considered in patients at risk. To confirm our results the prospective multicenter study Kraniopharyngeom 2000 on children and adolescents with craniopharyngioma was initiated (www.kraniopharyngeom.com).

We analyzed whether childhood craniopharyngioma predisposes to obesity and growth impairment. Height/length, body mass index (BMI), and hypothalamic involvement were evaluated in 90 patients at standardized ages and time points before, after, and at the time of diagnosis. Relevant decreases in height sd score (SDS) started at 10-12 months of age and persisted until diagnosis of childhood craniopharyngioma. Relevant increases in BMI SDS were detectable between 4 and 5 yr of age. Postoperative BMI SDS (yr 1-6) had a weak positive correlation with BMI SDS at the time of diagnosis. In linear regression analysis, hypothalamic tumor involvement (P < 0.001), ponderal index at birth (P = 0.014), and BMI SDS at age 6-7 months (P = 0.029) and at age 5 yr (P < 0.001) had relevant and independent impacts on the development of obesity. Patients with hypothalamic involvement (n = 48) presented lower ponderal index and BMI SDS at birth and higher BMI SDS at the time of diagnosis (P < 0.001) as well as during annual follow-up (P < 0.001) compared with patients without hypothalamic involvement (n = 42). From childhood (3.5-4 yr) to the time of diagnosis, growth rates were reduced for patients with hypothalamic tumor involvement. Patients without hypothalamic involvement presented reduced growth rates in early infancy (age 10-12 months) that persisted until diagnosis. We conclude that reduced growth rates occur quite early in history; BMI SDS increases occur later and are predictive of obesity. Hypothalamic involvement is the major risk factor for obesity in patients with childhood craniopharyngioma.

Purpose: Medulloblastomas represent the most frequent malignant brain tumors of childhood.They are supposed to originate from cerebellar neural precursor cells. Recently, it has been shown that Sonic Hedgehog^induced formation of medulloblastoma in an animal model is significantly enhanced by activation of the phosphatidylinositol 3 ¶-kinase (PI3K) signaling pathway. Experimental Design: To examine a role for PI3K/AKT signaling in the molecular pathogenesis of human medulloblastoma, we did an immunohistochemical study of the expression of Ser 473 -phosphorylated (p)-AKT protein in 22 medulloblastoma samples: All samples displayed p-AKT expression. To investigate if an activated PI3K/AKT pathway is required for medulloblastoma cell growth, we treated five human medulloblastoma cell lines with increasing concentrations of the PI3K inhibitor LY294002 and analyzed cellular proliferation and apoptosis. The antiproliferative effect could be antagonized by overexpressing constitutively active AKT. As the activation of PI3K/AKT signaling may be associated with alterations of the PTEN gene located at 10q23.3, a chromosomal region subject to frequent allelic losses in medulloblastoma, we screened PTEN for mutations and mRNA expression. Results: Proliferation of all of the medulloblastoma cell lines was dependent on PI3K/AKT signaling, whereas apoptosis was not prominently affected. Allelic loss was detected in 16% of the cases. One medulloblastoma cell line was found to carry a truncating mutation in the PTEN coding sequence. Even more important, PTEN mRNA and protein levels were found to be significantly lower in medulloblastomas compared with normal cerebellar tissue of different developmental stages. Reduction of PTEN expression was found to be associated with PTEN promoter hypermethylation in 50% of the tumor samples. Conclusions: We conclude that activation of the PI3K/AKT pathway constitutes an important step in the molecular pathogenesis of medulloblastoma and that dysregulation of PTEN may play a significant role in this context.

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