Prognostic Value of<sup>18</sup>F-FDG PET/CT in Diffuse Large B-Cell Lymphoma Treated with a Risk-Adapted Immunochemotherapy Regimen
Laure Michaud, Kurt S. Bantilan, Audrey Mauguen, Craig H. Moskowitz, Andrew D. Zelenetz, Heiko Schöder
Abstract
Early identification of patients with diffuse large B-cell lymphoma (DLBCL) who are likely to experience disease recurrence or refractory disease after rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) would be useful for improving risk-adapted treatment strategies. We aimed to assess the prognostic value of <sup>18</sup>F-FDG PET/CT parameters at baseline, interim, and end of treatment (EOT). <b>Methods:</b> We analyzed the prognostic impact of <sup>18</sup>F-FDG PET/CT in 166 patients with DLBCL treated with a risk-adapted immunochemotherapy regimen. Scans were obtained at baseline, after 4 cycles of R-CHOP or 3 cycles of RR-CHOP (double dose of R) and 1 cycle of CHOP alone (interim) and 6 wk after completing therapy (EOT). Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan–Meier and the impact of clinical/PET factors assessed with Cox models. We also assessed the predictive ability of the recently proposed International Metabolic Prognostic Index (IMPI). <b>Results:</b> The median follow-up was 7.9 y. International Prognostic Index (IPI), baseline metabolic tumor volume (MTV), and change in maximum SUV (ΔSUV<sub>max</sub>) at interim scans were statistically significant predictors for OS. Baseline MTV, interim ΔSUV<sub>max</sub>, and EOT Deauville score were statistically significant predictors of PFS. Combining interim PET parameters demonstrated that patients with Deauville 4–5 and positive ΔSUV<sub>max</sub> ≤ 70% at restaging (∼10% of the cohort) had extremely poor prognosis. The IMPI had limited discrimination and slightly overestimated the event rate in our cohort. <b>Conclusion:</b> Baseline MTV and interim ΔSUV<sub>max</sub> predicted both PFS and OS with this sequential immunochemotherapy program. Combining interim Deauville score with interim ΔSUV<sub>max</sub> may identify an extremely high-risk DLBCL population.