Patterns of Involved-Field Radiation Therapy Protocol Deviations in Pediatric Versus Adolescent and Young Adults With Hodgkin Lymphoma: A Report From the Children's Oncology Group AHOD0031.

PURPOSE

The presented protocol for pediatric intermediate-risk Hodgkin lymphoma evaluated the use of a dose-intensive chemotherapy regimen (ABVE-PC [doxorubicin, bleomycin, vincristine, etoposide, cyclophosphamide, prednisone]) with response-based therapy augmentation (addition of DECA [dexamethasone, etoposide, cisplatin, cytarabine]) or therapy reduction (elimination of radiation).

METHODS AND MATERIALS

A central review of the radiation therapy data for quality assurance was performed, and the association between radiation protocol deviation (RPD) and relapse was assessed in the pediatric group (age <15 years) and adolescent and young adult (AYA) group (age ≥15-21 years). Involved-field radiation therapy (IFRT) planning was reviewed before the start of treatment and at treatment completion. The records were reviewed through the Quality Assurance Review Center's central review to identify RPD, classified according to dose deviation (DD), volume deviation (VD), undertreatment (UT), and overtreatment (OT). DDs and VDs were further classified as major or minor.

RESULTS

Of the 1712 patients enrolled, 1155 received IFRT, of whom, 216 (18.7%) had RPDs. The DD and VD patterns were similar between the pediatric and AYA groups. Minor VDs were most common. UT RPDs accounted for 69% in the pediatric group and 75% in the AYA group. Of the 35 patients with relapse and a RPD, 29 had an undertreatment RPD. Among the patients who received IFRT, a significant difference was found in the cumulative incidence rates of relapse between the pediatric and AYA groups (P = .03); however, no significant difference was found between patients with and without RPD (P = .2).

CONCLUSIONS

Most RPDs were minor and consisted of UT in the AYA and pediatric populations both. No difference was observed in RPDs between the pediatric and AYA patients. Thus, in a well-defined and standardized protocol, the RPD distributions for AYA patients will be similar to those for pediatric population. However, the increased cumulative incidence of relapse in the AYA patients who had received IFRT compared with the pediatric population requires further exploration, given the potential differences in clinical outcomes in the AYA population.