Objective To investigate the value of baseline 18F-fluorodeoxyglucose (FDG) PET/CT metabolic parameters in primary and metastatic lesions for predicting the treatment efficacy and prognosis in patients with advanced non-small cell lung cancer (NSCLC) treated with first-line immunotherapy combined with chemotherapy.
Methods A retrospective analysis was conducted on clinical and imaging data from 86 patients with advanced NSCLC who underwent 18F-FDG PET/CT at the Affiliated Hospital of Qingdao University from December 2018 to September 2023. The patients included 73 males and 13 females, with an average age of (65.1±7.4) years. Treatment efficacy was evaluated after four cycles of immunotherapy, and patients were classified into a clinical benefit (CB) group and a non-clinical benefit (NCB) group. Metabolic parameters were measured using a cut-off values of 42% of the maximum standardized uptake value (SUVmax), including SUVmax of primary lesion, metabolic tumor volume of primary lesion (MTVp), total lesion glycolysis of primary lesion (TLGp), metabolic tumor volume of whole body (MTVwb), total lesion glycolysis of whole body (TLGwb), the ratio of SUVmax for metastatic to primary lesions (R-SUVmax), the ratio of metabolic tumor volume for metastatic to primary lesions (R-MTV), the ratio of total lesion glycolysis for metastatic to primary lesions (R-TLG). Normally distributed measurement data were compared using two independent sample t-test (equal variances assumed), whereas non-normally distributed measurement data were analyzed using Mann-Whitney U test. Count data were compared using chi-square test. Binary Logistic regression was performed for multivariate analysis, and a composite model was constructed on the basis of statistically significant parameters. Receiver operating characteristic (ROC) curves were plotted to determine the optimal cut-off values of each parameter and predictive performance. Progression-free survival (PFS) curves was plotted using the Kaplan-Meier method, and the Log-rank test was employed to compare differences in PFS among patients under different parameter cut-off values. Variables with statistical significance in univariate analysis (differences between groups) were included in a multivariate Cox proportional hazard regression model to identify independent predictors of PFS.
Results The CB group included 57 patients (66.28%, 57/86), and the NCB group included 29 patients (33.72%, 29/86). The median follow-up duration was 26.5 months. By the end of follow-up, disease progression occurred in 64 patients (74.42%, 64/86), with a median PFS of 8 months, ranging from 1 to 55 months. Univariate analysis revealed significant differences between CB group and NCB group in clinical stage, MTVp, TLGp, R-SUVmax, R-MTV, and R-TLG (χ2=5.570, Z=from −2.909 to −1.998; all P<0.05), these as risk factors for predicting the efficacy of immunotherapy in patients with advanced NSCLS. Multivariate analysis showed that clinical stage (OR=0.277, 95%CI: 0.085–0.909; P=0.034), R-MTV (OR=0.231, 95%CI: 0.068–0.780; P=0.018), and R-TLG (OR=1.812, 95%CI: 1.067–3.074; P=0.028) were independent predictors of immunotherapy efficacy in patients with advanced NSCLC. ROC curve analysis demonstrated an area under the curve of 0.696 (95%CI: 0.574–0.817) for the composite model, with a sensitivity of 0.554 and specificity of 0.852. Kaplan-Meier survival analysis indicated that advanced clinical stage, higher R-MTV, and higher R-TLG were associated with shorter patient survival and poorer prognosis. Cox proportional hazards regression model analysis identified R-MTV (HR=1.443, 95%CI: 1.109–1.877; P=0.006) and R-TLG (HR=0.862, 95%CI: 0.772–0.963; P=0.008) as independent prognostic factors for PFS in patients with advanced NSCLC.
Conclusions R-MTV, R-TLG, and clinical stage can predict immunotherapy efficacy in patients with advanced NSCLC. R-MTV and R-TLG are independent prognostic factors of PFS in NSCLC patients.
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