Interim 18F-FDG PET/CT improves the prognostic value of S-IPI, R-IPI and NCCN-IPI in patients with diffuse large B-cell lymphoma

The current study aimed to explore whether the efficiency of the standard International Prognostic Index (S-IPI), revised-IPI (R-IPI) and enhanced-IPI (NCCN-IPI) in evaluating the prognosis of patients with diffuse large B-cell lymphoma (DLBCL) may be improved by interim 18F-FDG PET/CT. A total of 185 patients with newly diagnosed DLBCL were enrolled in the current study. All patients underwent interim PET/CT following the 4th cycle of chemotherapy. Patients were divided into different risk groups using S-IPI, R-IPI and NCCN-IPI and further subdivided into risk groups using interim PET/CT. Interpretations were evaluated for 2-year progression-free survival (PFS) and overall survival (OS). With a median follow-up time of 44 months, the 2-year PFS and OS were 60% [95% confidence interval (CI) 53-67%] and 81% (95% CI 74-86%), respectively. Analysis of S-IPI and NCCN-IPI identified no significant difference in PFS and OS between high intermediate and high risk groups. However, there were significant differences in the PFS and OS between the low and low intermediate risk groups (P<0.01). Interim PET/CT was used to redistribute patients in the higher risk group into PET negative and positive groups (P<0.01) and arallel results were observed in the lower risk group. In R-IPI, interim PET/CT identified a significant difference between PFS and OS in the good and poor risk groups but not in the very good risk group. Therefore, the results of the current study indicate that S-IPI, R-IPI and NCCN-IPI are three clinically useful prognostic indexes for patients with DLBCL. Interim PET/CT may improve the prognostic value of S-IPI, R-IPI and NCCN-IPI in predicting 2-year PFS and OS, particularly in patients with a high IPI score.