Association of PET/CT Metabolic Parameters with Histologic Grade of Lung Adenocarcinoma: Implications for Surgical...

Background The grading system for invasive lung adenocarcinoma proposed by the International Association for the Study of Lung Cancer (IASLC) has been widely validated. However, the association of PET/CT with IASLC grade and its value in clinical decision-making is unknown. Purpose To investigate the association of PET/CT metabolic parameters with IASLC grade and determine the complementary clinical value of PET/CT in optimizing preoperative surgical decision-making in clinical stage IA (cIA) lung adenocarcinoma. Materials and Methods This retrospective study included consecutive patients who underwent preoperative PET/CT and complete resection for cIA lung adenocarcinoma between September 2020 and March 2022. Logistic regression was used to identify predictors of grade 3 lung adenocarcinoma. Multivariable Cox models assessed prognostic effects and interactions between maximum standardized uptake value (SUV_max) and surgical strategy. Propensity score matching was used to balance clinicopathologic characteristics across surgical strategies. Results The study included 2789 patients (median age, 62 years [IQR, 55-68 years]; 1574 women). Logistic regression analysis demonstrated a positive interaction between radiologic type and SUV_max (P = .008) in predicting grade 3 adenocarcinoma. Specific cutoff values for pure solid (cutoff of 4.25) and subsolid (cutoff of 2.30) nodules were identified. Positive interactions between SUV_max and surgery were observed exclusively in pure solid nodules (SUV_max-resection extent for overall survival [OS], P = .048; SUV_max-nodal dissection for OS, P = .045). Stratified analyses showed that segmentectomy and limited lymph node dissection were associated with worse outcomes only in hypermetabolic lesions (SUV_max > 4.25; resection extent hazard ratio [HR] for OS, 2.06 [P = .03]; nodal dissection HR for OS, 2.06 [P = .005]). SUV_max maintained robust predictive efficacy for grade 3 lung adenocarcinoma in the external cohort (area under the receiver operating curve, 0.72 for pure solid nodules and 0.74 for subsolid nodules). Conclusion In patients who underwent PET/CT and complete resection for clinical stage IA lung adenocarcinoma, maximum standardized uptake value was an independent predictor of grade 3 lung adenocarcinoma and helped identify high-risk patients treated with segmentectomy or limited nodal dissection. © RSNA, 2026 Supplemental material is available for this article.