The final analysis of GHSG HD11 study (not PET driven) showed that 30 Gy IFRT still remains the standard dose after 4 ABVD.

Early PET negativity might allow safe radiation de-escalation in patients achieving a metabolic complete response after 2 ABVD.

The aim of Priority trial is to explore whether radiotherapy could be safely deescalated to 20 Gy without loss of efficacy in patients treated with four cycles of ABVD who achieved complete metabolic response after the first two cycles.

Inclusion Criteria:

• Age ≥18 years;

• Histologically confirmed classical HL stage I, II unfavorable according to GHSG criteria;

• Patient with any nodal mass ≥ than 10 cm can be included

• No previous treatment for Hodgkin lymphoma;

• ECOG performance status 0 to 2;

• Presence of FDG-avid lymphoma lesions on baseline PET scan;

• Subject understands and voluntarily signs the informed consent form approved by the Independent Ethics Committee (IEC), prior to the initiation of any screening or study-specific procedures;

• Adequate organ and marrow function as defined below:

  • absolute neutrophil count > 1.0 x109/L
  • platelet count > 75 x109/L
  • Total bilirubin < 2 mg/dl without a pattern consistent with Gilbert's syndrome
  • Aspartate Transaminase and Alanine Transaminase (AST/ALT) < 3.0 X institutional Upper Limits of Normality (ULN)
  • Creatinine within normal institutional limits or creatinine clearance > 50 mL/min

• Women of childbearing potential must agree to use a highly effective method of contraception (oral contraceptives, contraceptive injections, contraceptive patch, intrauterine device) from the signature of informed consent until six months after the last dose of treatment;

• Men must agree to use a highly effective method of contraception (barrier contraception or abstinence, when this is in line with the usual lifestyle of the subject) from the signature of informed consent until six months after the last dose of treatment;

• Women of childbearing potential must have a negative serum pregnancy test at screening.

Exclusion Criteria:

• Patients who meet any of the following criteria are not eligible to enroll:
• Stage II B- III- IV
• Hodgkin Lymphoma as "composite lymphoma" or nodular lymphocyte prevalence histological subtype
• Active HBV and HCV infection
• HIV seropositivity
• Pre-treatment with chemotherapy or radiation therapy
• Malignant disease within the last 5 years (excluding basal skin tumors and carcinoma in situ of the cervix)
• Women who are pregnant or breast feeding
• Absence of FDG-avid lymphoma lesions on baseline PET scan
• Significant history of neurologic, psychiatric, endocrinological, metabolic, immunologic, or hepatic disease that would preclude participation in the study or compromise ability to give informed consent.