AUTHOR=Li Hongyan , Wang Min , Zhang Yajing , Hu Fan , Wang Kun , Wang Chenyang , Gao Zairong 

TITLE=Prediction of prognosis and pathologic grade in follicular lymphoma using 18F-FDG PET/CT

JOURNAL=Frontiers in Oncology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2022.943151

DOI=10.3389/fonc.2022.943151

ISSN=2234-943X

ABSTRACT=<sec><title>Purpose</title><p>We investigated the utility of a new baseline PET parameter expressing lesion dissemination and metabolic parameters for predicting progression-free survival (PFS) and pathologic grade in follicular lymphoma (FL).</p></sec><sec><title>Methods</title><p>The baseline <sup>18</sup>F-FDG PET/CT images of 126 patients with grade 1–3A FL were retrospectively analyzed. A novel PET/CT parameter characterizing lesion dissemination, the distance between two lesions that were furthest apart (<italic>D</italic><sub>max</sub>), was calculated. The total metabolic tumor volume and total lesion glycolysis (TLG) were computed by using 41% of the maximum standardized uptake value (SUV<sub>max</sub>) thresholding method.</p></sec><sec><title>Results</title><p>The 5-year PFS rate was 51.9% for all patients. In the multivariate analysis, high <italic>D</italic><sub>max</sub> [<italic>P</italic> = 0.046; hazard ratio (HR) = 2.877], high TLG (<italic>P</italic> = 0.004; HR = 3.612), and elevated serum lactate dehydrogenase (<italic>P</italic> = 0.041; HR = 2.287) were independent predictors of PFS. A scoring system for prognostic stratification was established based on these three adverse factors, and the patients were classified into three risk categories: low risk (zero to one factor, <italic>n</italic> = 75), intermediate risk (two adverse factors, <italic>n</italic> = 29), and high risk (three adverse factors, <italic>n</italic> = 22). Patients in the high-risk group had a shorter 3-year PFS (21.7%) than those in the low- and intermediate-risk groups (90.6 and 44.6%, respectively) (<italic>P</italic> &lt; 0.001). The C-index of our scoring system for PFS (0.785) was superior to the predictive capability of the Follicular Lymphoma International Prognostic Index (FLIPI), FLIPI2, and PRIMA-Prognostic Index (C-index: 0.628–0.701). The receiver operating characteristic curves and decision curve analysis demonstrated that the scoring system had better differentiation and clinical utility than these existing indices. In addition, the median SUV<sub>max</sub> was significantly higher in grade 3A (36 cases) than in grades 1 and 2 FL (90 cases) (median: 13.63 vs. 11.45, <italic>P</italic> = 0.013), but a substantial overlap existed (range: 2.25–39.62  vs. 3.17–39.80).</p></sec><sec><title>Conclusion</title><p>TLG and <italic>D</italic><sub>max</sub> represent two complementary aspects of the disease, capturing the tumor burden and lesion dissemination. TLG and <italic>D</italic><sub>max</sub> are promising metrics for identifying patients at a high risk of progression or relapse. Additionally, SUV<sub>max</sub> seems to have some value for distinguishing grade 3A from low-grade FL but cannot substitute for biopsy.</p></sec>