Comparison of prognostic values of primary tumor and nodal ¹⁸F-fluorodeoxyglucose uptake in non-small cell lung cancer with N1 disease

Introduction: We hypothesized that, in non-small cell lung cancer (NSCLC) with N1 metastasis, N1 nodal ¹⁸F-fluorodeoxyglucose (FDG) status offers independent and incremental prognostic value. Methods: We enrolled 106 NSCLC patients with pathology-confirmed N1 metastasis. N1 node FDG positivity, primary tumor maximum standard uptake value (SUV_max), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured. Kaplan-Meier method and Cox regression analyses were performed for cancer-specific survival (CSS) and disease-free survival (DFS). Results: Subjects were 67 males and 39 females (61.9 ± 9.4 years). Eighty-one (76.4%) and 25 (23.6%) had pathologic stage IIB and IIIA NSCLC, respectively. All underwent complete tumor resection. FDG-positive N1 nodes were larger and had higher primary tumor SUV_max. During a follow-up of 42 months, there were 56 recurrences and 31 cancer deaths. Significant univariate predictors were stage, no adjuvant therapy, and FDG-positive nodes for DFS, and stage, no adjuvant therapy, node size, tumor MTV, TLG, and SUV_max, and FDG-positive nodes for CSS. Independent predictors on multivariate analyses were FDG-positive nodes (HR = 3.071, p = 0.003), greater tumor TLG (HR = 3.224, p = 0.002), and no adjuvant therapy (HR = 3.631, p < 0.001) for poor CSS, and FDG-positive nodes (HR = 1.771, p = 0.040) and no adjuvant therapy (HR = 2.666, p = 0.002) for poor DFS. Harrell’s concordance and net reclassification improvement tests showed that CSS prediction was significantly improved by the addition of N1 FDG status to a model containing tumor TLG. Conclusion: N1 node FDG status can be useful for predicting the outcome of NSCLC patients with N1 metastasis beyond that provided by other prognostic variables. Key Points: • In NSCLC with N1 disease, N1 node FDG status is useful as a prognostic predictor. • FDG-positive N1 nodes provide additional prognostic value beyond TLG of primary tumor. • Combining TLG of primary tumor and N1 node uptake can stratify the survival of patients.