Background: Hodgkin lymphoma (HL) treatment protocols for children, adolescents and young adults traditionally differ, but the biological and clinical justification for this remains uncertain.
Material and methods: We compared age-dependent clinical presentation and treatment and outcome for 1072 classical HL patients 0-24 years diagnosed in Denmark (1990-2010) and Sweden (1992-2009) in pediatric (n = 315, Denmark <15 years, Sweden <18 years) or adult departments (n = 757). Distribution of clinical characteristics was assessed with Pearson's chi2-test and Mantel-Haenszel trend test. The Kaplan-Meier method was used for survival analyses. Hazard ratios (HR) were used to compare the different treatment groups and calculated using Cox regression.
Results: Children (0-9 years) less often presented with advanced disease than adolescents (10-17 years) and young adults (18-24 years) (stage IIB-IV: children 32% vs. adolescents 50%, and adults 55%; p < .005). No variation in overall survival (OS) was seen between pediatric and adult departments or by country. Danish pediatric patients received radiotherapy (36%) less frequently than Swedish pediatric patients (71%) (p < .0001). Ten-year event-free survival (EFS) was lower among Danish pediatric patients (0-14 years) (0.79; 95% confidence interval (CI) 0.70-0.86) than among Swedish pediatric patients (0-17 years) (0.88; 95% CI 0.83-0.92), HR (1.93; 95% CI 1.08-3.46). A similar pattern was seen between adult patients in the two countries: Denmark 10-year EFS 0.85 (95% CI 0.81-0.88), Sweden 0.88 (95% CI 0.84-0.91), adjusted HR 1.51 (95% CI 1.03-2.22).
Conclusion: Adolescents and young adults shared similar clinical presentation suggesting a rationale of harmonized treatment for these groups. Both adult and pediatric protocols provided high OS with no significant difference between the departments. The less frequent use of radiotherapy in Danish pediatric patients corresponded to a lower EFS, but comparable OS in all groups confirmed effective rescue strategies for the relapsing patients.