Interim positron emission tomography-computed tomography (PET/CT) may allow stratification of patients with diffuse large B-cell lymphoma (DLBCL) to good- and poor-prognosis groups according to 2-year OS, even within lower- and higher-risk International Prognostic Index (IPI) groups, according to results from a retrospective study published in the International Journal of Hematology.
Response to frontline therapy for DLBCL can be highly variable. Though IPI is widely used for evaluating prognosis in DLBCL, it can fail to identify patients who will experience poor outcomes, and treatment outcomes within the same IPI group can be heterogeneous. Interim PET/CT can detect patients who are not responding to therapy prior to the end of therapy examination.
This study retrospectively assessed 104 patients with treatment-naive DLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP)-like regimens who underwent interim PET/CT during treatment.
Median follow-up was 37.5 months (range, 4-98). In univariate analysis for OS, IPI of 3 or higher (P =.003), increased lactate dehydrogenase (P =.045), advanced age (P =.051), bulky disease (P =.017), ECOG performance status of 2 or higher (P =.002), and positive interim PET/CT (P <.001) all correlated with inferior prognosis. In multivariate analysis, however, only positive interim PET/CT (hazard ratio [HR], 5.836; 95% CI, 2.435-13.988; P <.001) and high IPI score (HR, 3.940; 95% CI, 1.430-10.858; P =.008) were independently prognostic of worse OS.
The estimated 2-year OS was 82.2% and 5-year OS was 73.8% across all patients. Patients with negative interim PET/CT had a 2-year OS of 93.5%, compared with 81.5% in patients with positive interim PET/CT (P ≤.001).
The 2-year PFS was 75% and 5-year PFS was 63.3% across all patients. As with OS, patients with positive interim PET/CT had worse 2-year PFS (67.4%) compared with patients with negative interim PET/CT (79.9%; P =.011).
Additional resolution of higher- and lower-risk patients within IPI risk categories through interim PET/CT results occurred.
Noted limitations of the study include its retrospective design, the variability in frontline therapeutic regimens, and the inconsistent timing of interim PET/CT. The authors suggested a need for confirming these results in prospective studies with a larger number of patients.
1. Nyilas R, Farkas B, Bicsko RR, et al. Interim PET/CT in diffuse large B-cell lymphoma may facilitate identification of good-prognosis patients among IPI-stratified patients. Int J Hematol. 2019;110(3):331-339.