PET-adapted omission of radiotherapy in early stage Hodgkin lymphoma-a systematic review and meta-analysis

Background: Hodgkin lymphoma (HL) is one of the most common malignancies in young adults and one of the most curable cancers worldwide. With interim PET-scan, HL treatment is in the process of being modified: a negative or positive interim PET separates good and poor responders to initial therapy; therefore, deescalated or escalated additional treatment is currently being evaluated in clinical trials.

Methods: The Cochrane Library, MEDLINE and conference proceedings were searched until 05.2015 for randomized controlled trials (RCTs) comparing FDG-PET-adapted therapy to standard treatment in untreated early stage HL patients with a negative PET-scan. Two review authors independently screened search results and extracted relevant study data. Hazard ratios (HR) were used for time-to-event data and risk rations (RR) for dichotomous data, with 95% confidence intervals (CI). If trials were considered sufficiently clinically homogenous, fixed-effect model was used to pool data.

Results: Three RCTs involving a total of 1480 participants were included in the meta-analysis. Only one trial provided data for OS, without evidence for a difference between both arms (HR 0.51; 95% CI 0.15-1.68). All three trials assessed progression free survival, which was inferior in the PET-adapted arms (without radiotherapy) compared to the standard treatment arms (HR 2.40; 95% CI 1.63-3.53). Adverse events were reported in one study only, without evidence for a difference between both arms. There were no data on long-term adverse events, quality of life and treatment-related mortality available

Conclusion: To date, no robust data on survival and adverse events are available. However, this systematic review found that PFS was significantly decreased in the PET-adapted treatment arm (without radiotherapy) in early stage HL patients.