2.2 Participants
This study included two groups of children: one group with solid tumors
(case group) and one group of healthy children (control group). For the
case group, eligible children had to meet the following criteria: 1)
were diagnosed with solid tumors (e.g., sarcomas, germ-cell tumors, and
neuroblastoma); 2) received at least one cycle of chemotherapy; 3)
completed chemotherapy within one year; and 4) agreed to participate.
Children were excluded if they did not receive any chemotherapy, could
not understand and answer the questionnaires, or had a cognitive
impairment, such as Down’s syndrome. Regarding the control group,
healthy children who had not received antibiotics within the past 4
weeks and who had not been diagnosed with chronic or autoimmune diseases
or conditions that can influence the gut microbiome profiles were
included. These two groups were matched by age, sex, and race during
recruitment.