Clinical trial designs of recently completed and ongoing phase 3 randomized studies of response-adapted therapy for adult early-stage HL. (A) EORTC/LYSA/FIL H10F study. *None of the following present: large mediastinal mass, age ≥50 years, high ESR, or 4 or more areas. (B) EORTC/LYSA/FIL H10U study. *Any of the following present: large mediastinal mass, age ≥50 years, high ESR, and/or 4 or more areas. (C) UK-led RAPID study; all PET-3⁺ patients received a 4th cycle of ABVD followed by 30 Gy of IFRT. (D) GHSG HD16 favorable trial. *None of the following present: large mediastinal mass, extranodal disease, high ESR, or 3 or more areas. (E) GHSG HD17 unfavorable trial. *Any of the following present: large mediastinal mass, extranodal disease, high ESR, and/or 3 or more areas. High ESR for all of above defined as: >50 mm without B symptoms or ESR <30 mm with B symptoms. esc indicates escalated; ESR, erythrocyte sedimentation rate; LYSA, Lymphoma Group and the Lymphoma Study Association; FIL, Fondazione Italiana Linfomi; and pts, patients.