PET/CT surveillance in patients with Hodgkin lymphoma in first remission is associated with low positive predictive value and high costs

Background. The value of performing post-therapy routine surveillance imaging in patients with Hodgkin lymphoma is controversial. This study evaluates the utility of positron emission tomography / computed tomography using 2-[18F]fluoro-2-deoxyglucose (PET/CT) for this purpose and in situations with suspected lymphoma relapse. Design and Methods. We conducted a multicenter retrospective study. Patients with newly diagnosed Hodgkin lymphoma achieving at least a partial remission on first-line therapy were eligible if they received PET/CT surveillance during follow-up. Two types of surveillance PET/CTs were analyzed; routine PET/CT when patients showed no signs of relapse at referral to PET/CT, and clinically indicated PET/CT when recurrence was suspected. Results. A total of 211 routine and 88 clinically indicated PET/CTs were performed in 161 patients. In ten of 22 patients with Hodgkin lymphoma recurrence, a routine PET/CT was the primary tool for the diagnosis of relapse. Extranodal disease, interim PET positive lesions and PET activity at response evaluation were all associated with a PET/CT diagnosed preclinical relapse. The true positive rates of routine PET/CT vs. clinically indicated PET/CT were 5 and 13%, respectively (p=0.02). The overall positive predictive value and negative predictive value of PET/CT was 28% and 100%, respectively. The estimated cost per routine PET/CT diagnosed relapse was 50.778 USD. Conclusions. A negative PET/CT reliably rules out a relapse. The high false positive rate, however, is an important limitation and a confirmatory biopsy is mandatory for the diagnosis of a relapse. With no proven survival benefit for patients with a pre-clinically diagnosed relapse, the high costs and low positive predictive value make PET/CT unfit for routine surveillance of Hodgkin lymphoma patients.