Radiation Therapy

As previously mentioned, most newly diagnosed children are treated with risk-adapted chemotherapy, either alone or in combination with consolidative radiation therapy. Radiation therapy volumes can vary and have protocol-specific definitions, but they generally encompass lymph node sites initially involved at the time of diagnosis, without extensive inclusion of uninvolved regions, or positron emission tomography (PET)-avid sites at either interim or end-of-therapy assessment. Radiation therapy field reductions are made to account for tumor regression with chemotherapy.[45]

One study investigated the effects of central review of the interim fluorine F 18-fludeoxyglucose (18F-FDG) PET–computed tomography (CT) scan response (iPET) assessment on treatment allocation in the risk-based, response-adapted COG AHOD1331 (NCT02166463) study for pediatric patients with high-risk Hodgkin lymphoma. The study evaluated the results of 573 patients after two cycles of chemotherapy. There was good agreement between central and institutional iPET analysis, with a concordance rate of 89.7% (514 of 573). Of 126 patients who were considered iPET positive by institutional review, 30% were found to be iPET negative by central review. Thus, these patients could avoid being treated with radiation therapy. Conversely, of 447 patients who were considered iPET negative by institutional review, 4.7% were considered positive by central review, which led to these patients receiving radiation therapy.[46]