Response assessment after an inductive CHOP or CHOP-like regimen with or without rituximab in 103 patients with diffuse large B-cell lymphoma: Integrating ¹⁸fluorodeoxyglucose positron emission tomography to the International Workshop Criteria

Background: Revised response criteria for aggressive lymphomas have been proposed (Cheson, J Clin Oncol , 2007) stressing the role of ¹⁸fluorodeoxyglucose-positron emission tomography (PET) in posttreatment evaluation. The value of PET after four cycles compared with the International Workshop Criteria (IWC) remains to be established. Patients and methods: In all, 103 patients with untreated diffuse large B-cell lymphoma were prospectively enrolled to evaluate the prognostic impact of PET after two and four cycles. Results: Median age was 53 years (19-79), 68% male. The International Prognostic Index was low = 22%, low-intermediate = 19%, intermediate-high = 33% and high risk = 26%. Treatment consisted of cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) (30%) or dose-intensified CHOP (70%), with rituximab (49%) or without (51%). Ninety-nine patients were evaluated by PET and IWC at four cycles: 77 (78%) had a negative PET, while 22 (22%) remained positive. The 5-year event-free survival (EFS) was 36% for patients with a positive PET versus 80% with a negative examination, whatever the response [complete response (CR) versus partial response (PR)] according to IWC (P < 0.0001). Positive PET patients had a 5-year EFS of 58% if in CR/CR unconfirmed by IWC and 0% if not (P < 0.0001). The same observations could be made in patients treated with and without rituximab. Conclusion: The integration of PET in treatment evaluation offers a powerful tool to predict outcome.