A Preoperative Nomogram for Predicting Occult Lymph Node Metastasis in Left Upper Lobe Adenocarcinoma

Background: Non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma, remains a leading cause of cancer-related mortality worldwide. Despite advancements in preoperative imaging techniques, occult lymph node metastases (OLNM) continue to pose a significant diagnostic challenge—especially in tumors located in the left upper lobe (LUL), owing to their complex anatomical structure and unique patterns of lymphatic spread. This study aims to develop a preoperative predictive model for OLNM in patients with clinical stage IA (cIA) LUL adenocarcinoma, with the goal of improving risk stratification and informing individualized treatment strategies. Methods : A retrospective cohort study was conducted involving 452 patients diagnosed with cIA LUL adenocarcinoma who underwent surgical resection between 2018 and 2022. Clinical, radiological, and pathological data were collected, including tumor location, tumor size, mean computed tomography (CT) attenuation value, and serum carcinoembryonic antigen (CEA) levels. Univariate and multivariate logistic regression analyses were used to identify independent predictors of OLNM. A predictive nomogram was subsequently developed and validated using receiver operating characteristic (ROC) curve analysis, calibration plots, and decision curve analysis (DCA). Results: OLNM was detected in 12.4% of patients. Multivariate analysis identified central tumor location (odds ratio [OR] = 10.38, p < 0.001), CT tumor size ≥ 2.05 cm (OR = 3.65, p < 0.001), mean CT attenuation value ≥ -19.80 Hounsfield units (HU) (OR = 1.01, p < 0.001), and elevated CEA levels ≥ 2.45 ng/ml (OR = 1.19, p = 0.001) as independent preoperative predictors of OLNM. The nomogram demonstrated excellent discriminative performance (area under the curve [AUC] = 0.935) and clinical utility, facilitating individualized risk assessment. Conclusion: This study proposes a lobe-specific predictive model for OLNM in patients with LUL adenocarcinoma, incorporating anatomical, radiological, and serological parameters. The resulting nomogram enhances preoperative risk stratification and supports the development of tailored surgical and adjuvant treatment strategies. These findings underscore the importance of lobe-specific considerations in NSCLC management and may contribute to improved clinical outcomes through more precise therapeutic decision-making.