Abstract P035

In-Field Recurrence Patterns Following Consolidation Radiotherapy after BrECADD in Advanced-Stage Hodgkin Lymphoma: A Secondary Analysis of the Randomized Phase 3 GHSG HD21 Trial

Purpose/Objective: While the GHSG HD21 trial demonstrated superior efficacy for the BrECADD regimen over escalated BEACOPP (eBEACOPP) in advanced-stage Hodgkin lymphoma (HL), the necessity of routine consolidation radiotherapy (RT) for end-of-treatment PET (EOT-PET)-positive patients remains debated. This analysis evaluates the role of consolidation RT by assessing patterns of in-field recurrence following both chemotherapy regimens.

Materials/Methods: Data from advanced-stage HL patients receiving consolidation RT in the randomized phase 3 HD21 trial were retrospectively analyzed. Following central review recommendation, EOT-PET-positive patients received 30 Gy RT. To determine the role of consolidation RT, EOT-PET scans and subsequent imaging were analyzed in relapsed patients to identify in-field recurrences. Descriptive statistics were performed on baseline and treatment characteristics. In-field recurrence rates were calculated using cumulative incidence functions.

Results: EOT-PET-positivity occurred at an identical rate of 17% in both treatment arms (n=127/734 after eBEACOPP vs n= 125/739 after BrECADD). RT was administered to 112 EOT-PET-positive patients in the eBEACOPP group and 104 patients in the BrECADD group. Image analysis revealed that local treatment failure was rare in both groups: in-field relapses occurred in only 5 patients after eBEACOPP and 2 patients after BrECADD. The 60-month cumulative incidence of in-field recurrence was 4.5% (95% CI, 0.6-8.4) for eBEACOPP compared to just 2.0% (95% CI, 0.0-4.8) for BrECADD (HR, 0.43; 95% CI, 0.08–2.21).

Conclusion: Consolidation RT following frontline BrECADD provides outstanding local control even for EOT-PET-positive patients. Notably, the in-field recurrence rate was numerically lower after BrECADD than after eBEACOPP (2.0% vs. 4.5%). While EOT-PET positivity rates were identical between arms, they increased compared to the GHSG HD15 trial. Collectively, these findings suggest that in the era of modern PET technology with enhanced spatial resolution and highly effective systemic therapy, a distinct subset of EOT-PET-positive patients may not profit from consolidation RT. However, this must be carefully weighed against the excellent local efficacy of RT and the risk of undertreatment. To safely de-escalate RT, future trials should integrate advanced metrics like metabolic tumor volume or minimal residual disease assessment to precisely identify those who truly derive a therapeutic benefit.