Postchemotherapy PET evaluation correlates with patient outcome in paediatric Hodgkin's disease

Aim To evaluate the role of postchemotherapy FDG PET and compare it with other predictive factors in paediatric Hodgkin's disease (HD). Materials and methods In this retrospective study, 98 paediatric patients with HD (enrolled in eight Italian centres) were analysed. Their mean age was 13.8 years (range 5-19 years). A PET scan was performed at the end of chemotherapy and reported as positive or negative on the basis of visual and/or semiquantitative analysis. True outcome was defined as remission or disease on the basis of combined criteria (clinical, instrumental and/or histological) with a mean follow-up period of 25 months. Statistical analyses were performed for the postchemotherapy PET results and other potential predictive factors (age cut-off, stage, presence of bulky masses and therapeutic group) with respect to patient outcome and progression-free survival (PFS). Results Overall the patients had a mean PFS of 23.5 months (range 4-46 months): 87 achieved remission (88.8%) and 11 showed disease. Of the 98 patients, 17 were positive on postchemotherapy PET . Seven patients (41%) showed disease during follow-up, and relapse occurred in only four out of the 81 patients who were negative on PET (p = 0.0001). Kaplan-Meier analysis demonstrated significant correlations between PFS and the postchemotherapy PET result (p = 0.0001) and a cut-off age at diagnosis of 13.3 years (p = 0.0337), whereas disease stage (p = 0.7404), therapeutic group (p = 0.5240) and presence of bulky masses (p = 0.2208) were not significantly correlated with PFS. Multivariate analysis confirmed a statistically significant correlation with PFS only for the postchemotherapy PET findings (p = 0.0009). Conclusion In paediatric HD, age at diagnosis and postchemotherapy PET results are the main predictors of patient outcome and PFS, with FDG PET being the only independent predictive factor for PFS.