Abstract
BackgroundLymph node ratio (LNR) has been suggested to be an effective prognostic tool for stratifying non-small cell lung cancer (NSCLC) cases. In this study, we sought to determine cancer-specific survival (CCS) of NSCLC cases from the SEER registry and used the X-tile method to optimize CCS-based LNR cut-off points for prognostic stratification of node-positive NSCLC.MethodsCSS and other clinicopathologic variables were retrieved from the SEER registry. Kaplan-Meier methods were used to calculate CSS. The optimal cut-off points for LNR classification were determined by the X-tile approach. Multivariate Cox regression analysis was performed to identify independent risks of CSS.ResultsTotally 11,341 lung cancer patients were included. Their median CSS was 22 months (range 0,143). The median LNR was 0.22 (Q1,Q3: 0.11, 0.50). X-tile analysis showed that the optimal LNR cut-off points were 0.28 and 0.81, dividing the cohort into low (LNR1 ≤ 0.28; n = 6580, 58%), middle (0.28 < LNR2 < 0.81; n = 3025, 26.7%), and high (LNR3 > 0.81; n = 1736, 15.3%) subsets. Kaplan-Meier analysis showed that patients with a low LNR had a significantly higher CCS versus patients with middle or high LNR (P < 0.001). Multivariate competing risks regression analysis revealed that LNR was an independent and significant adverse predictor of CSS (LNR2 vs. LNR1: SHR: 1.56, 95%CI: 1.47,1.67, P < 0.001; LNR3 vs. LNR1: SHR: 2.54, 95%CI: 2.30,2.80, P < 0.001).ConclusionsLNR is an independent prognostic factor of node-positive NSCLC and its optimal cut-off values established using the robust x-tile method effectively define subpopulations of node-positive NSCLC cases, which is important in guiding selection of treatment strategies clinically.
Highlights
Lymph node ratio (LNR) has been suggested to be an effective prognostic tool for stratifying nonsmall cell lung cancer (NSCLC) cases
614,355 patients were diagnosed with lung cancer during the study period; 11,341 of them met the eligibility criteria and were included in the current study
Kaplan-Meier analysis showed that patients with a low LNR had a significantly higher cancer-specific survival (CCS) versus patients with middle or high LNR (Fig. 4e)
Summary
Lymph node ratio (LNR) has been suggested to be an effective prognostic tool for stratifying nonsmall cell lung cancer (NSCLC) cases. We sought to determine cancer-specific survival (CCS) of NSCLC cases from the SEER registry and used the X-tile method to optimize CCS-based LNR cut-off points for prognostic stratification of node-positive NSCLC. For patients with primary non-metastatic NSCLC, accurate staging of lymph node status is important for both prognosis and treatment decisions on the appropriateness and timing of surgery, radiotherapy and systemic therapy [2]. The classical tumor, lymph node, and metastasis (TNM) staging system remains the most convenient, reliable and acknowledged predictor of outcome of NSCL C patients. Positive node category (pN), which is based on the number of involved lymph nodes, is affected by adequacy of lymph nodes retrieved or examined. Though the number of lymph nodes examined has been correlated with the survival of NSCLC patients [4], and despite improvement in lymph node assessment over the decade, the number of lymph nodes examined still varies widely by institutions [5] or across regions in the USA [4]
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