2.4 Procedures
Participants in the case group were recruited during their routine outpatient clinic visits. Clinical collaborators from CHOA identified eligible patients and asked them whether they were willing to discuss the study with our research team. After they agreed, one trained research staff described the study, consented parents, and assented age-eligible patients. Questionnaires were distributed to the children to complete during clinic visits, and parents were instructed on the stool specimen collection at home. The electronic medical records of the pediatric patients with solid tumor were used to collect the demographic information, health history, cancer diagnosis and treatment-related information. For the control group, all the procedures were the same, excluding the use of the electronic medical records.