In children, both malnutrition and sarcopenia are associated with prolongation of hospital stay, increased morbidity, mortality, and health-related complications. While the decrease in muscle strength refers to "probable sarcopenia", "sarcopenia" is confirmed by adding the decrease in muscle quantity/quality to this situation. In case all three criteria are together, "severe sarcopenia" is mentioned. The aim of this study is the evaluate whether there is a difference in the risk of sarcopenia and related factors in pediatric oncological children compared to healthy controls matched for body mass index group, physical activity level group, sex, and age. Our research was planned as cross-sectional and descriptive research. Patients diagnosed with pediatric oncologic cancer will be included. Demographic data, malnutrition, the risk for sarcopenia, physical activity status, smartphone addiction, fatigue, and hospital anxiety and depression will be evaluated with questionnaires. Muscle strength (manual muscle strength assessment), Muscle quantity (the bilateral calf circumference with a tape measure and by bioelectrical impedance analysis (BIA)), and physical performance (Short Physical Performance Battery) will be evaluated by the physiotherapist. The data of the research will be evaluated with the SPSS package program. After examining the conformity of the data that can be measured in statistical evaluations to a normal distribution with a single sample Kolmogorov Smirnov test, one-way analysis of variance will be applied for comparisons between groups for those with normal distribution, and t-test for independent groups. Kruskal Wallis analysis of variance and Mann Whitney U test will be used in the evaluation of data that do not conform to the normal distribution. Pearson χ2 and Yates corrected Pearson χ2 test Fisher's exact χ2 will be used for qualitative data. As descriptive statistics, numbers and percentages will be given for categorical data, and Median (Min-Max) values and arithmetic mean±standard deviation will be given for quantitative data. For all statistics, the limit of significance will be chosen as bidirectional p\<0.05.
Inclusion Criteria: * Be between the ages of 2-18 years * Being under pediatric oncology outpatient/clinical follow-up * Being able to stand unaided without using a cane/walker Exclusion Criteria: * Having any of the diagnoses of hypertension, any cardiac arrhythmia-conduction disorders, coronary artery disease, heart failure, diabetes mellitus, hyperlipidemia, cardiovascular diseases, COPD, pulmonary infection, active infection. * Depression Illness that causes balance problems * Peripheral vascular disease * Presence of disease that prevents standing up with support. * Presence of diseases that may cause muscle mass loss (cerebral palsy, neuromuscular disease, congenital metabolic disorder, brain damage) mental retardation * Children with a severe emotional disorder, adjustment disorder * Physical disability to prevent safe and appropriate testing * Having used anti-flu medicine in the last 1 week * Failure to obtain consent.