Although interim 18F-fluoro-2-dexoy-D-glucose-positron emission tomography (FDG-PET)/computerized tomography (CT) scan has emerged as a powerful prognostic tool in predicting treatment outcome in Hodgkin's lymphoma (HL) and diffuse large B cell lymphoma (DLBCL), the positive predictive value (PPV) of interim PET/CT scanning has not been determined in patients with peripheral T cell lymphoma (PTCL). The sequential interim PET/CT was prospectively investigated to determine whether it provided additional prognostic information and could be a positive predictable value for the treatment of PTCL.
Fifty-five newly diagnosed patients with PTCL were enrolled from Sep. 2005 to July 2009 at a single institution. The PET/CT analysis was performed at the time of diagnosis and mid-treatment of CHOP/CHOP-like or other chemotherapy (EPOCH and IMEP). The clinical stage and response of the patients were assessed according to revised response criteria for aggressive lymphomas (Cheson, J Clin Oncol, 2007). The positivity of interim PET/CT was determined based on the semi-quantitative assessment of the maximal standardized uptake value (Cut-off SUVmax value of 3.0).
Median age was 55 years (range: 23–77). 31 patients (56.4%) presented in advanced stages and 13 (23.6%) had bone marrow involvements. The histological subtypes were 40.0% PTCL-unspecified (n=22), 5.1% angioimmunoblastic T cell (n=5), 38.2% nodal or extranodal NK/T cell (n=21), and others. At diagnosis, 24 patients (43.6%) were classified as high-risk by the international prognostic index (IPI) and 22 (40%) were classified as high-risk (more than 2 factors) by the prognostic index for PTCL (PIT). 47 patients could be assessed the interim response and 24 patients (43.6%) remained positive metabolic uptakes in interim PET/CT. The patients with positive interim PET/CT showed a significantly higher relapse rate (75.0%) than those with negative interim PET/CT (43.5%) (P =0.028). After following median 12.7 months, positivity of interim PET/CT was the prognostic factor for both OS and PFS, with a hazard ratio of 4.11 (1.30 – 13.01) and 3.26 (1.19 – 8.96), respectively. Six patients (10.9%) who determined to have positive interim PET/CT were revealed false-positive uptakes after locoregional biopsy (PPV of 0.75).
Interim PET/CT has a significant predictive value for disease progression and survival of PTCL. The patients with positive interim PET/CT response should be considered an intensive therapeutic plan for overcoming their poor clinical outcome.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.