This pilot trial compares drug exposure levels using a new method for dosing vincristine in infants and young children compared to the standard dosing method based on body surface area (BSA) in older children. Vincristine is an anticancer drug used to a variety of childhood cancers. The doses anticancer drugs in children must be adjusted based on the size of the child because children vary significantly in size (height, weight, and BSA) and ability to metabolize drugs from infancy to adolescence. The dose of most anticancer drugs is adjusted to BSA, which is calculated from a patients weight and height. However, infants and young children have more severe side effects if the BSA is used to calculate their dose, so new dosing models have to be made to safely give anticancer drugs to the youngest patients. This new method uses a BSA-banded approach to determine the dose. Collecting blood samples before and after a dose of the drug will help researchers determine whether this new vincristine dosing method results in equivalent drug levels in the blood over time in infants and young children compared to older children.

This randomized clinical phase III trial studies how well web-based physical activity intervention works in improving long term health in children and adolescents with cancer. Regular physical activity after receiving treatment for cancer may help to maintain a healthy weight and improve energy levels and overall health.

This study aims to use clinical and biological characteristics of acute leukemias to screen for patient eligibility for available pediatric leukemia sub-trials. Testing bone marrow and blood from patients with leukemia that has come back after treatment or is difficult to treat may provide information about the patient's leukemia that is important when deciding how to best treat it, and may help doctors find better ways to diagnose and treat leukemia in children, adolescents, and young adults.