Preoperative prognostic prediction for invasive pulmonary adenocarcinoma: Impact of 18F-FDG PET/CT semi-quantitative parameters associated with new histological subtype classification.

Aims: To explore the preoperative predictive value of ¹⁸F-FDG PET/CT for poor prognostic histologic subtypes of invasive pulmonary adenocarcinoma (IPA) under new classification.

Materials and methods: This study included 316 patients. Histopathology of IPA was evaluated by recording the percentage of each histologic component. PET/CT parameters were compared among IPAs with different risks of recurrence. Optimum cutoff values of PET/CT parameters were calculated using ROC curve analysis. Overall survival (OS) and disease-free survival (DFS) were calculated using Kaplan-Meier method, and survival differences between groups were tested using log-rank test. Multivariate analysis for survival was performed using the Cox regression model.

Results: Patients were divided into low (LRR), intermediate (IRR), and modified high (mHRR) risk of recurrence group incorporating typical (HRR-T) and nontypical (HRR-NT) subgroups based on histologic patterns. There were significant differences in SUV_max, SUV_mean, SUV_min, SUV_SD, TLG, and tumor size among three groups. HRR-NT had lower SUV_max, SUV_mean, SUV_min, SUV_SD and TLG than HRR-T subgroup, and higher SUV_max, SUV_mean, SUV_min, SUV_SD, MTV, TLG and tumor size than IRR group. ROC curve analysis showed that SUV_max had highest AUC (0.815) in distinguishing LRR and IRR. TLG had highest AUC (0.741) in distinguishing IRR and mHRR. Multivariable analysis showed that tumor size and SUV_max were independent predictors of DFS and OS.

Conclusions: High risk of recurrence of IPA exhibited higher ¹⁸F-FDG uptake and tumor size. Tumor size and SUV_max could be used as preoperative surrogates for the IASLC grading system. ¹⁸F-FDG PET/CT can improve the preoperative prognostic prediction for IPA patients.