J Clin Oncol 2015 Aug 6;33(23):2523-9. Epub 2015 Jul 6.
Christoph Mamot and Mario Bargetzi, Cantonal Hospital Aarau, Aarau; Dirk Klingbiel, Christine Biaggi, and Corinne Rusterholz, Swiss Group for Clinical Cancer Research Coordinating Center; Thomas Pabst, Inselspital Bern, Bern; Felicitas Hitz and Christoph Driessen, Cantonal Hospital St. Gallen, St. Gallen; Christoph Renner, Hirslanden Zürich; Thomas Hany, Magnetic Resonance Imaging Roentgen Zürich; Andrei Samarin, University Hospital Zürich, Zürich; Ulrich Mey, Cantonal Hospital Graubuenden, Chur; Miklos Pless, Cantonal Hospital Winterthur, Winterthur; Fatime Krasniqi and Stephan Dirnhofer, University Hospital of Basel, Basel; Emanuele Zucca, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland; and Federica Gigli and Giovanni Martinelli, European Institute of Oncology Milan, Milan, Italy.
Purpose: Our main objective was to prospectively determine the prognostic value of [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) after two cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone given every 14 days (R-CHOP-14) under standardized treatment and PET evaluation criteria.
Patients And Methods: Patients with any stage of diffuse large B-cell lymphoma were treated with six cycles of R-CHOP-14 followed by two cycles of rituximab. PET/CT examinations were performed at baseline, after two cycles (and after four cycles if the patient was PET-positive after two cycles), and at the end of treatment. PET/CT examinations were evaluated locally and by central review. The primary end point was event-free survival at 2 years (2-year EFS).
Results: Median age of the 138 evaluable patients was 58.5 years with a WHO performance status of 0, 1, or 2 in 56%, 36%, or 8% of the patients, respectively. By local assessment, 83 PET/CT scans (60%) were reported as positive and 55 (40%) as negative after two cycles of R-CHOP-14. Two-year EFS was significantly shorter for PET-positive compared with PET-negative patients (48% v 74%; P = .004). Overall survival at 2 years was not significantly different, with 88% for PET-positive versus 91% for PET-negative patients (P = .46). By using central review and the Deauville criteria, 2-year EFS was 41% versus 76% (P < .001) for patients who had interim PET/CT scans after two cycles of R-CHOP-14 and 24% versus 72% (P < .001) for patients who had PET/CT scans at the end of treatment.
Conclusion: Our results confirmed that an interim PET/CT scan has limited prognostic value in patients with diffuse large B-cell lymphoma homogeneously treated with six cycles of R-CHOP-14 in a large prospective trial. At this point, interim PET/CT scanning is not ready for clinical use to guide treatment decisions in individual patients.