Background: Diffuse large B-cell lymphoma(DLBCL)is an aggressive lymphoma.The optimal follow-up strategy for patients(pts)in remission is not clear.The goal of this study is to determine the utility of surveillance scans in a large,prospective,multi-institutional cohort of DLBCL pts.Methods: Patients were enrolled in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource(MER),a prospective cohort of newly diagnosed lymphoma pts.All pts were followed for events including relapse,re-treatment,and death with events verified by medical records.Patients eligible for this study had biopsy proven DLBCL and were treated with anthracycline based immunochemotherapy(IC).Initial and post-treatment management was per treating physician.Medical records were re-reviewed in pts with events for clinical details at relapse and relationship to planned follow-up visits and surveillance scans.Results: 644 pts with DLBCL treated with IC were enrolled in MER from 2002-2009.Median age was 63 years(range 18-92),54%were men,and median f/u was 59 months(range 8-116).537 pts entered post-treatment observation; 109(20%)of the 537 pts relapsed and 41 died from other causes.42%of relapses were in the first 12 months following diagnosis,27%between 12-24 months,and 31%>24 months.In the 109 who relapsed,62%of pts(62/100,9 unknown)presented to their physician earlier than a planned follow-up visit due to symptoms.At the time of relapse,68%were symptomatic,42%of pts had abnormal physical exam,and 55%had elevated LDH; 87%of pts had ≥1 of these features.Of the 38 pts with relapse detected at a planned visit,26 had clinical features of relapse and 12 pts had relapse detected solely by planned surveillance scan; 4 pts had relapse of low-grade or other subtype and 8 had DLBCL relapse(4 of whom had equivocal/positive PET at the end of IC).Thus,surveillance scanning detected DLBCL relapse prior to clinical manifestations in only 8/537 pts(1.5%)observed post DLBCL therapy.Conclusions: The vast majority of DLBCL relapses occur outside of planned follow-up visits and are accompanied by symptoms,physical exam,or laboratory abnormalities.Routine surveillance scans post-therapy add little to detection of DLBCL relapse.