Prognostic Significance of PET Score in Early-Stage Hodgkin Lymphoma
In an analysis from the UK RAPID study reported in the Journal of Clinical Oncology, Barrington et al found that a postchemotherapy positron-emission tomography (PET) score of 5 was associated with poorer outcomes among patients with early-stage Hodgkin lymphoma.
Study Details
In the trial, patients with stage IA–IIA disease and no mediastinal bulk underwent PET evaluation after three cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine. One hundred and forty-three PET-positive patients (PET score = 3–5) received an additional cycle and involved-field radiotherapy, and 419 patients in complete metabolic remission were randomly assigned to receive involved-field radiotherapy (n = 208) or no additional treatment (n = 211). The association between PET score and pretreatment risk factors with disease-specific event-free survival was assessed.
Prognostic Significance
High PET score was associated with poorer event-free survival before (P < .001) and after adjustment (P = .01) for baseline risk stratification. Increased risk of progression or Hodgkin lymphoma–related death was observed only among patients with postchemotherapy PET score of 5 (defined as uptake ≥ 3 times maximum liver uptake), with this group having a hazard ratio [HR] of 9.4 (95% confidence interval [CI] = 2.8–31.3) compared with patients with PET score of 3 and HR of 6.7 (95% CI = 1.4–31.7) compared with patients with PET score of 4. PET score of 5 was also associated with poorer progression-free and overall survival.
No significant associations were observed between pretreatment European Organisation for Research and Treatment of Cancer or German Hodgkin Study Group risk groups and event-free survival either before or after adjustment for PET score (all P > .4).
The investigators concluded, “In RAPID, a positive PET scan did not carry uniform prognostic weight; only a PET score of 5 was associated with inferior outcomes. This suggests that in future trials involving patients without B symptoms or mediastinal bulk, a score of 5 rather than a positive PET result should be used to guide treatment escalation in early-stage [Hodgkin lymphoma].”
Sally F. Barrington, MSc, MD, of the School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Leukaemia and Lymphoma Research Fund, Lymphoma Research Trust, Teenage Cancer Trust, UK Department of Health and Social Care, and National Institute for Health Research. For full disclosures of the study authors, visit jco.ascopubs.org.
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