Outcomes of Patients with Positive Interim Positron Emission Tomography (PET) Continuing ABVD in the Clinical Setting

SIMPLE SUMMARY: This study aimed to highlight limitations in the use of interim PET (iPET) for treatment decisions and prognostication in the frontline management of Hodgkin’s lymphoma. It reinforces the observation from the ECHELON-1 study that outcomes of patients with a positive interim PET who nonetheless continue treatment with ABVD are not as dismal as previously described. Furthermore, we describe the performance of PET positivity grading by a quantitative measure based on SUV ratios compared to the subjective Deauville scoring. ABSTRACT: Recent prospective clinical trial data suggest that patients with Hodgkin’s lymphoma who continue treatment with ABVD, despite failing to attain a complete metabolic response on interim PET (PET2+), may fare better than previously published. We describe the outcomes of PET2+ patients who continued ABVD and compare the performance of a quantitative measure based on the lesion-to-liver SUV ratio (LLS qPET2+) to that of the subjective Deauville criteria (dvPET2+). We analyzed all patients with newly diagnosed advanced-stage Hodgkin lymphoma treated with frontline ABVD at the Memorial Sloan Kettering Cancer Center between 2008 and 2017. Eligibility was set to correspond with the RATHL inclusion criteria. Images were reviewed by two nuclear medicine physicians and discordant cases were resolved with a third expert in consensus. qPET2+ was defined as LLS ≥ 1.3. We identified 227 patients of whom 25% (57) were qPET2+, but only 14% (31) were dvPET2+. Forty-eight patients (84%) continued ABVD with a 3-year PFS of 70% for qPET2+ and 64% for dvPET2+. In conclusion, interim PET interpretation in clinical practice may be associated with a higher rate of scans deemed positive. Irrespective of the criteria for PET2 positivity, a subset of patients may continue ABVD without a dismal outcome.