Pediatric Oncologists are not surgeons so they do not perform any surgery.
Instead pediatric oncologists use medications and chemotherapy to treat child cancer and diseases.
Pediatric Oncologists and hematologists also examine and diagnose patients, order diagnostic tests and prescribe treatments.
If the child needs to have surgery then the child will be sent to a surgeon who's qualified for the surgery they will be performing.
A surgeon does mainly surgery while other doctors including pediatric oncologists use other treatments for the cancer and other diseases.
If you're not a surgeon you cannot perform surgery on anyone.