Consolidative mediastinal radiotherapy for advanced-stage classical Hodgkin lymphoma with bulky disease in patients who achieve complete response after chemotherapy in PET-CT era

BACKGROUND: The role of consolidation mediastinal radiotherapy (RT) for mediastinal bulky disease in advanced-stage classical Hodgkin lymphoma (cHL) is controversial in the positron emission tomography/computed tomography (PET-CT) era. MATERIALS AND METHODS: We reviewed the medical charts of patients with advanced-stage (clinical stage IIX–IVX) cHL and mediastinal bulky that achieved a complete response after first line chemotherapy treatment between August 2010 and December 2020 and compared the results of those who received with those who did not receive consolidation mediastinal RT. Inclusion criteria required PET-CT imaging for staging and response assessment. RESULTS: We included 115 patients; 91 received mediastinal RT and 24 did not. Patient’s characteristics were balanced between the two groups. The median age in patients that received and did not receive mediastinal RT was 28 years and 24.5 years, respectively. Median International Prognostic Score among patients that received and did not receive mediastinal RT was 2 and 2.5, respectively. Disease free survival (DFS) was statistically better in patients that received mediastinal RT (p = 0.013). Two-year DFS for patients that received and did not receive mediastinal RT was 95.2% [95% confidence interval (95% CI): 87.6–98.2%] and 76.4% (95% CI: 52.2–89.4%), respectively. Overall survival (OS) was not different between the two groups (p = 0.617). In multivariate analysis, not receiving mediastinal radiotherapy and only achieving partial response (vs. complete response) after 2 cycles of chemotherapy were factors predictive of lower DFS. CONCLUSION: DFS, but not OS, was superior in patients that received mediastinal RT.