Limited role for surveillance PET-CT scanning in patients with diffuse large B-cell lymphoma in complete metabolic remission following primary therapy

Background: The usefulness of positron emission tomography with computed tomography (PET-CT) in the surveillance of patients with diffuse large B-cell lymphoma (DLBCL) in complete metabolic remission after primary therapy is not well studied. Methods: We performed a retrospective review of our database between 2002 and 2009 for patients with de novo DLBCL who underwent surveillance PET-CT after achieving complete metabolic response (CMR) following primary therapy. Results: Four-hundred and fifty scans were performed in 116 patients, with a median follow-up of 53 (range 8-133) months from completion of therapy. Thirteen patients (11%) relapsed: seven were suspected clinically and six were subclinical (all within first 18 months). The positive predictive value in patients with international prognostic index (IPI) <3 was 56% compared with 80% in patients with IPI >= 3. Including indeterminate scans, PET-CT retained high sensitivity 95% and specificity 97% for relapse. Conclusion: Positron emission tomography with computed tomography is not useful in patients for the majority of patients with diffuse large B-cell lymphoma in CMR after primary therapy, with the possible exception of patients with baseline IPI >= 3 in the 18 months following completion of primary therapy. This issue could be addressed by a prospective clinical trial.