Effect of histological subtype on the efficacy of perioperative chemotherapy in pulmonary sarcomatoid carcinoma: a retrospective study based on SEER population.

Background: The efficacy of perioperative chemotherapy (PC) in pulmonary sarcomatoid carcinoma (PSC) is controversial. We conducted this study to investigate the effect of different histological subtypes on the efficacy of PC in PSC patients. Methods: Clinicopathological data of 811 PSC patients of different histological subtypes were collected from the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier method and log-rank test were used to evaluate the effects of PC on the overall survival (OS) and cancer-specific survival (CSS) in different subtypes of PSC patients. Propensity score matching (PSM) was used to reduce potential confounding effects. Subgroup analyses were conducted to further investigate the efficacy of PC in patients with different characteristics. Results: A total of 210 (25.89%) enrolled PSC patients received PC. PC was not associated with OS or CSS benefit in pleomorphic carcinoma, giant cell carcinoma, or spindle cell carcinoma patients, neither before nor after matching. But survival benefit of PC was observed in carcinosarcoma patients both before (5-year OS: 48.79% vs. 38.75%, P=0.01) and after (5-year OS: 51.29% vs. 17.54%, P=0.003) matching. Subgroup analyses showed that in patients whose tumor larger than 4 cm, PC was still associated with improved survival in carcinosarcoma, but not in the other histological subtypes of PSC. Conclusions: The efficacy of PC varies between different subtypes of PSC. Survival benefit of PC was only observed in carcinosarcoma patients, but not in pleomorphic carcinoma, giant cell carcinoma, or spindle cell carcinoma patients. Histological subtype should be considered when treating PSC patients with PC.

The Gap in the Thickness: Estimating Effectiveness of Pulmonary Nodule Detection in Thick- and Thin-Section CT Images with 3D Deep Neural Networks.

BACKGROUND AND OBJECTIVES: There is a noticeable gap in diagnostic evidence strength between the thick and thin scans of Low-Dose CT (LDCT) for pulmonary nodule detection. When the thin scans are needed is unknown, especially when aided with an artificial intelligence nodule detection system. METHODS: A case study is conducted with a set of 1,000 pulmonary nodule screening LDCT scans with both thick (5.0mm), and thin (1.0mm) section scans available. Pulmonary nodule detection is performed by human and artificial intelligence models for nodule detection developed using 3D convolutional neural networks (CNNs). The intra-sample consistency is evaluated with thick and thin scans, for both clinical doctor and NN (neural network) models. Free receiver operating characteristic (FROC) is used to measure the accuracy of humans and NNs. RESULTS: Trained NNs outperform humans with small nodules < 6.0mm, which is a good complement to human ability. For nodules > 6.0mm, human and NNs perform similarly while human takes a fractional advantage. By allowing a few more FPs, a significant sensitivity improvement can be achieved with NNs. CONCLUSIONS: There is a performance gap between the thick and thin scans for pulmonary nodule detection regarding both false negatives and false positives. NNs can help reduce false negatives when the nodules are small and trade off the false negatives for sensitivity. A combination of human and trained NNs is a promising way to achieve a fast and accurate diagnosis.

A Comprehensive Comparison of Different Nodal Subclassification Methods in Surgically Resected Non-Small-Cell Lung Cancer Patients.

INTRODUCTION: The revision of the N descriptor in non-small-cell lung cancer has been widely discussed in the past few years. Many different subclassification methods based on number or location of lymph nodes have been proposed for better distinguishing different N patients. This study aimed to systematically collect them and provide a comprehensive comparison among different subclassification methods in a large cohort. METHOD: Pathological N1 or N2 non-small-cell lung cancer patients undergoing surgical resection between 2005 and 2016 in the Western China Lung Cancer Database were retrospectively reviewed. A literature review was conducted to collect previous subclassification methods. Kaplan-Meier and multivariable Cox analyses were used to examine the prognostic performance of subclassification methods. Decision curve analysis, Akaike's information criterion, and area under the receiver operating curve concordance were also performed to evaluate the standardized net benefit of the subclassification methods. RESULTS: A total of 1625 patients were identified in our cohort. Eight subclassification methods were collected from previous articles and further grouped into subclassification based on number categories (node number or station number), location categories (lymph node zone or chain) or combination of number and location categories. Subclassification based on combination of lymph node location and number tended to have better discrimination ability in multivariable Cox analysis. No significant superiority among the different subclassification methods was observed in the three statistical models. CONCLUSION: Subclassification based on the combination of location and number could be used to provide a more accurate prognostic stratification in surgically resected NSCLC and is worth further validation.

Does surgical margin affect recurrence and survival after sublobar pulmonary resection for lung cancer?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was: How does surgical margin distance affect recurrence and survival after sublobar pulmonary resection for lung cancer? Altogether, 172 papers were found using the search strategy, of which 12 studies with 1946 stage I non-small-cell lung cancer (NSCLC) patients using sublobar resection (wedge resection or segmentectomy) represented to be the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Overall, 11 cohort studies and 1 prospective study were included. Four cohort studies demonstrated positive prognostic significance of surgical margin with specific cut-off points in each paper (ranged from 9 to 15 mm). Two retrospective studies and 1 prospective study found that a margin-to-tumour ratio of ≥1 was associated with better cytology and prognosis results. Other 5 studies showed that larger margin distance provided a favourable prognosis for NSCLC patients with poor-prognostic factors, including solid-dominant type, high invasive component size and Spread through Air Spaces-positive subtype. After reviewing all the included articles, we conclude that the standard of margin distance of >10 mm or margin-to-tumour ratio ≥ 1 should be recommended for stage I NSCLC patients undergoing sublobar resection, especially in wedge resection. Patients with poor-prognostic factors like solid-predominant tumour or non-lepidic adenocarcinoma may benefit from larger margin distance and the proper margin distance for them still needs to be determined. For Spread through Air Spaces-positive patients, sublobar resection may not be the alternative to lobectomy.

Electrocautery vs. Stapler in Comparing Safety for Segmentectomy of Lung Cancer: A Meta-Analysis.

Background: Electrocautery and staplers are regarded as the two most common surgical instruments for dissecting the intersegmental plane in segmentectomy. We performed a meta-analysis to compare electrocautery and staplers in terms of their safety and effects. Methods: A systematic search strategy was performed using PubMed, and the retrieval time was up to April 1, 2020. Odds ratio (OR) and mean differences (MDs) with 95% CI were applied to determine the effectiveness of dichotomous or continuous variables, respectively. Results: Six studies including 385 patients were included. The electrocautery had a higher incidence rate of postoperative complication [OR= 1.92, 95% CI (1.12, 3.28), P = 0.02)] and air leak [OR: 3.91, 95% CI (1.64, 9.35), P = 0.002)]. No significant difference was found in the comparison of surgery time, blood loss, and duration of tube days or hospitality days. Conclusions: Our study indicated that patients under segmentectomy were associated with better safety by using stapler than electrocautery in the reduction of postoperative complications.

Skip metastasis in mediastinal lymph node is a favorable prognostic factor in N2 lung cancer patients: a meta-analysis.

BACKGROUND: Skip metastasis is a common lymph node metastatic pattern in non-small cell lung cancer (NSCLC). The relationship between skip metastasis and specific clinicopathologic factors and the prognostic value of skip metastasis are controversial. METHODS: A systematic search and analysis of skip metastasis in NSCLC was conducted in the databases of PubMed, EMBASE, and Web of Science up to Dec 2019. Summarized hazard ratio (HR), mean difference (MD), and odds ratio (OR) with associated 95% confidence intervals (CI) were evaluated to investigating the relationship between skip metastasis and overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS) and clinicopathological features in NSCLC. RESULTS: 29 studies with a total of 1,806 skip and 4,670 non-skip N2 patients were included. The upper lobe tumor showed a higher rate of skip metastasis compared with lower lobe one (RR =1.16, 95% CI: 1.00-1.34, P=0.044, I2=39.8%). The presence of skip metastasis correlated with superior overall survival (HR =0.74, 95% CI: 0.66-0.83, P<0.001, I2=48.2%) and DFS or RFS (HR =0.71, 95% CI: 0.61-0.84, P<0.001, I2=18.2%). Further subgroup analyses indicated similar results in articles that reported intrapulmonary lymph node dissection (HR =0.67, 95% CI: 0.57-0.77, P<0.001, I2=0). CONCLUSIONS: The results indicate that the presence of skip metastasis is associated with a marked increase in survival of NSCLC patients compared to patients with non-skip N2 metastasis. These results suggest that skip metastasis might be a distinct subgroup for purposes of N staging of NSCLC patients, and intrapulmonary lymph node assessment is needed.

Sentinel lymph node biopsy in head and neck cutaneous melanomas: A PRISMA-compliant systematic review and meta-analysis.

BACKGROUND: Head and neck melanomas (HNMs) behave differently from cutaneous melanomas in other sites, and the efficacy of sentinel lymph node biopsy (SLNB) for patients with HNMs remains controversial. METHODS: Studies on prognosis following SLNB were included. The prognostic role of SLNB and other potential predictors were analyzed using pooled relative risk (RR) or hazard ratio (HR). RESULTS: Pooled statistics showed that SLNB improved overall survival of HNMs patients (HR = 0.845; 95% CI: 0.725-0.986; P = .032). The positive status of SN was proved as a risk factor of poor prognosis in HNMs (HR = 3.416; 95% CI: 1.939-6.021; P < .001). SLNB did not have significant correlation with lower recurrences (RR = .794; 95% CI: 0.607-1.038; P = .091). CONCLUSIONS: SLNB is associated with better overall survival and the SN status is a promising risk factor of poor prognosis for HNMs patients.

Automatic airway tree segmentation based on multi-scale context information.

PURPOSE: Airway tree segmentation plays a pivotal role in chest computed tomography (CT) analysis tasks such as lesion localization, surgical planning, and intra-operative guidance. The remaining challenge is to identify small bronchi correctly, which facilitates further segmentation of the pulmonary anatomies. METHODS: A three-dimensional (3D) multi-scale feature aggregation network (MFA-Net) is proposed against the scale difference of substructures in airway tree segmentation. In this model, the multi-scale feature aggregation (MFA) block is used to capture the multi-scale context information, which improves the sensitivity of the small bronchi segmentation and addresses the local discontinuities. Meanwhile, the concept of airway tree partition is introduced to evaluate the segmentation performance at a more granular level. RESULTS: Experiments were conducted on a dataset of 250 CT scans, which were annotated by experienced clinical radiologists. Through the airway partition, we evaluated the segmentation results of the small bronchi compared with the state-of-the-art methods. Experiments show that MFA-Net achieves the best performance in the Dice similarity coefficient (DSC) in the intra-lobar airway and improves the true positive rate (TPR) by 7.59% on average. Besides, in the entire airway, the proposed method achieves the best results in DSC and TPR scores of 86.18% and 79.31%, respectively, with the consequence of higher false positives. CONCLUSION: The MFA-Net is competitive with the state-of-the-art methods. The experiment results indicate that the MFA block improves the performance of the network by utilizing multi-scale context information. More accurate segmentation results will be more helpful in further clinical analysis.

Lobe-Specific Node Dissection Can Be a Suitable Alternative to Systematic Lymph Node Dissection in Highly Selective Early-Stage Non-Small-Cell Lung Cancer Patients: A Meta-Analysis.

PURPOSE: Whether the lobe-specific lymph node dissection is an alternative to systematic lymph node dissection for early-stage non-small-cell lung cancer remains controversial. An elaborate meta-analysis was conducted to evaluate the effects of lobe-specific lymph node dissection in early-stage patients. METHODS: A systematic literature search was conducted up to February 19, 2020 in PubMed, Ovid, Web of Science, and China National Knowledge Infrastructure databases. The outcomes including overall survival (OS), complications, and recurrence rate were extracted and analyzed. RESULTS: Nine studies including one randomized controlled trial (RCT) and eight retrospective cohort studies with 8499 non-small-cell lung cancer patients were included. The results indicated that lobe-specific lymph node had a lower rate of postoperative complication (relative risk [RR]: 0.83, 95% confidence interval [CI]: 0.72-0.95, P = 0.006). No significant difference was observed between lobe-specific lymph node and systematic lymph node dissection in OS (hazard rate = 1.12, 95% CI: 0.81-1.54, P = 0.501) with high heterogeneity (I2 = 71.9%). CONCLUSION: Lobe-specific lymph node can reach a comparable long-term prognosis in some highly selected patients. However, these results should be viewed cautiously with the existence of high heterogeneity. Due to the high heterogeneity, a strict patient selection process by experienced thoracic surgeons was recommended before validating lobe-specific lymph node.

Prognostic significance of the N1 classification pattern: a meta-analysis of different subclassification methods.

OBJECTIVES: The number of positive lymph node stations has been viewed as a subclassification in the N1 category in the new revision of tumour node metastasis (TNM) staging. However, the survival curve of these patients overlapped with that of some patients in the N2 categories. Our study focused on the prognostic significance of different subclassifications for N1 patients. METHODS: We systematically searched PubMed, Ovid, Web of Science and the Cochrane Library on the topic of N1 lymph node dissection. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were used to assess the prognostic significance of N1 metastases. I2 statistics was used to evaluate heterogeneity among the studies: If significant heterogeneity existed (P ≤ 0.10; I2 >50%), a random effect model was adopted. RESULTS: After a careful investigation, a total of 17 articles were included in the analysis. The results showed that patients with non-small-cell lung cancer with multistation N1 disease have worse survival compared with those with single-station N1 disease (HR 1.53, 95% CI 1.32-1.77; P < 0.001; I2 = 5.1%). No significant difference was observed between groups when we assessed the number of positive lymph nodes (single or multiple) (HR 1.25, 95% CI 0.96-1.64; P = 0.097; I2 = 72.5%). Patients with positive hilar zone lymph nodes had poorer survival than those limited to the intrapulmonary zone (HR 1.80, 95% CI 1.57-2.07; P < 0.001; I2 = 0%). A subgroup analysis conducted according to the different validated lymph node maps showed a stable result. CONCLUSIONS: Our result confirmed the prognostic significance of the N1 subclassification based on station number. Meanwhile, location-based classifications, especially zone-based, were also identified as prognostically significant, which may need further confirmation and validation in the staged population.

The Favorable Prognostic Factors for Superior Sulcus Tumor: A Systematic Review and Meta-Analysis.

Background: Superior sulcus tumor is a rare non-small cell lung cancer with poor prognosis. Exploring the potential prognostic factors of patients with superior sulcus tumor and adopting individualized treatment for patients with different prognostic factors are of great significance for the prolongation of patients' lives. To figure out the prognostic factors of upper sulcus tumors, a meta-analysis was conducted. Method: We searched all the articles published until January 2020 in PubMed, Embase, and Web of Science databases, and the search strategy included the following terms, combining superior sulcus tumor and prognosis. Hazard ratio (HR) with associated confidential interval (CI) was evaluated for the purpose of investigating prognostic factors for superior sulcus tumor. STATA 16.0 was used for analysis of extracted data and assessment of publication bias. Result: Fifteen eligible studies, which had 1,009 patients with superior sulcus tumor, were included in this meta-analysis. The studies were published between 1994 and 2018, and the patient recruitment periods ranged from 1974 to 2016. The median follow-up time ranged from 18 to 95 months. The meta-analysis indicated that lower T stage (HR, 1.63; 95% CI, 1.35-1.97), lower N stage (HR, 3.08; 95% CI: 2.37-3.99), negative surgical margin (HR, 0.25; 95% CI, 0.17-0.38), and pathologic complete response (HR, 0.55; 95% CI, 0.39-0.77) were favorable prognostic factors. Conclusion: We found that T stage, N stage, surgical margin, and pathologic complete response are prognostic factors for superior sulcus tumor. To reach a better long-term survival, patients with these negative prognostic factors may need a more aggressive treatment, while more studies should be conducted to further validate these results and explore a more effective treatment.

The clinicopathological features and prognosis of primary pulmonary lymphoepithelioma-like carcinoma: A systematic review and meta-analysis.

BACKGROUND: Primary pulmonary lymphoepithelioma-like carcinoma (PPLELC) was a sparse subtype of unclassified lung cancer. The clinicopathologic features, prognostic factors and multimodality treatment regimens of LELC remain inconclusive. We conducted this systematic review and meta-analysis to address this deficit in current knowledge. METHODS: We searched PubMed, Embase, and Web of Science to filtrate studies investigating on clinical features and prognostic factors of LELC up to Sep 9th, 2020. Fixed and random effect models were generated to present the incorporated hazard ratios (HR) and odds ratios (OR) with 95% confidence intervals (CI). The quality and heterogeneity of the included studies were also evaluated carefully. RESULTS: This systematic review and meta-analysis included 13 retrospective studies with a total of 1294 patients. The incidence of programmed cell death-ligand 1 (PD-L1) expression in PPLELC varied from 63.3% to 75.8%. Positive PD-L1 expression was more likely to be found in patients under 60 years old (OR = 2.16, 95%CI: 1.19-3.89, P = 0.01) and was associated with worse disease-free survival (DFS) compared with negative PD-L1 expression (HR = 2.99, 95%CI: 1.23-7.28, P = 0.02). The pooled results showed that stage was the prognostic factor for both overall survival (OS) and DFS. Moreover, a significantly better outcome of PPLELC was observed in men (HR = 0.56, 95%CI: 0.33-0.95, P = 0.03) and patients who received radiation (HR = 0.46, 95%CI: 0.22-0.96, P = 0.04). CONCLUSION: PD-L1 expression was high in PPLELC patients. It was significantly associated with age under 60 and the unfavorable DFS. Stage and gender could be the prognostic factor for OS. Radiation could be the effective therapy for PPLELC.

Chylothorax after Lung Cancer Surgery: A Key Factor Influencing Prognosis and Quality of Life.

Chylothorax is caused by the accumulation of chylous fluid in the pleural cavity due to the injury of the thoracic duct or its tributaries. Chylothorax following lung cancer surgery, especially pulmonary resection and mediastinal lymph node dissection, is a raw potential postoperative complication as previously reported. Chylothorax might lead to a high mortality rate if not addressed in a timely fashion. This article reviews the anatomy of the thoracic duct, risk factors of postoperative chylothorax, diagnoses and management with chylothorax, and intraoperative prevention of chylothorax. With the development of researches on postoperative chylothorax, more effective treatment and prevention measures need to be proposed to better solve this clinical problem.

Clinical significance of tumour mutation burden in immunotherapy across multiple cancer types: an individual meta-analysis.

BACKGROUND: Biomarkers for stratifying patients that could benefit from immune checkpoint inhibitors are necessary. Tumour mutation burden has recently become a promising biomarker in cancer, but the associations between tumour mutation burden and outcomes of immune checkpoint inhibitors treatment were not well-documented in present studies. METHODS: We searched PubMed, Web of Science and EMBASE databases up to 1 October 2019. Studies evaluated the association between tumour mutation burden and clinical outcomes were included. Hazard ratios and odds ratios were applied to estimate the association of tumour mutation burden score with overall survival, progression-free survival and response rate, respectively. The best cut-off value was chosen by best discriminated overall survival using Contal and O'Quigley method. RESULTS: Twenty-two studies involving 6171 patients in diverse cancers were included. The individual participant data meta-analysis demonstrated that high tumour mutation burden was associated with better overall survival (HR = 0.57, 95% CI = 0.50-0.64) and progression-free survival (HR = 0.50, 95% CI = 0.40-0.63) and higher response rate. The best cut-off values in each cancer type were 17.7/MB in non-small cell lung cancer, 7.9/MB in bladder cancer, 6.1/MB in melanoma, 12.3/MB in colorectal cancer, 6.9/MB in esophagogastric cancer, 10.5/MB in head and neck cancer. The pooled meta-analysis showed the prognosis value was robust and the sensitivity, specificity and area under the receiver operating characteristic curves in predicting response rates were 0.63, 0.71 and 0.73, respectively. CONCLUSIONS: The present meta-analysis indicates tumour mutation burden is a promising predictor of immune checkpoint inhibitors therapy but the cut-off value differs in different cancers.

Does percutaneous transthoracic needle biopsy increase the risk of pleural recurrence in patients with stage I lung cancer?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was: does percutaneous transthoracic needle biopsy (PTNB) increase the risk of pleural recurrence in patients with stage I lung cancer? Altogether, 298 papers were found using the reported search, of which 7 cohort studies and 1 meta-analysis represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Four cohort studies suggested an association between PTNB and pleural recurrence in patients with stage I lung cancer, while the other 3 cohort studies found that PTNB had no impact. One meta-analysis (the largest study) including 5 of the cohort studies above concluded that PTNB increased the risk of pleural recurrence among patients with stage I lung cancer with subpleural lesions. Based on the available evidence, it was suggested that there may be an association between PTNB and pleural recurrence in patients with stage I lung cancer, especially for patients with subpleural lesion.

MediMLP: Using Grad-CAM to Extract Crucial Variables for Lung Cancer Postoperative Complication Prediction.

Lung cancer postoperative complication prediction (PCP) is significant for decreasing the perioperative mortality rate after lung cancer surgery. In this paper we concentrate on two PCP tasks: (1) the binary classification for predicting whether a patient will have postoperative complications; and (2) the three-class multi-label classification for predicting which postoperative complication a patient will experience. Furthermore, an important clinical requirement of PCP is the extraction of crucial variables from electronic medical records. We propose a novel multi-layer perceptron (MLP) model called medical MLP (MediMLP) together with the gradient-weighted class activation mapping (Grad-CAM) algorithm for lung cancer PCP. The proposed MediMLP, which involves one locally connected layer and fully connected layers with a shortcut connection, simultaneously extracts crucial variables and performs PCP tasks. The experimental results indicated that MediMLP outperformed normal MLP on two PCP tasks and had comparable performance with existing feature selection methods. Using MediMLP and further experimental analysis, we found that the variable of "time of indwelling drainage tube" was very relevant to lung cancer postoperative complications.

Efficacy of Transcutaneous Electronic Nerve Stimulation in Postoperative Analgesia After Pulmonary Surgery: A Systematic Review and Meta-Analysis.

OBJECTIVE: The aim of the study was to identify the analgesic efficacy and safety of transcutaneous electronic nerve stimulation in postoperative pain after pulmonary surgery. DESIGN: Electronic databases (PubMed, Embase, Web of Science, and CENTRAL) were systematically searched from their inception to June 2019. The continuous variables were pooled as the weighted mean difference with correlated 95% confidence interval. Results were recognized as significant when a P value is less than 0.05. Subgroup analyses, sensitivity analyses, and quality assessment were performed. RESULTS: Altogether, 10 studies were included. The pooled results indicated that transcutaneous electronic nerve stimulation group conferred lower pain intensity score on the first postoperative day (weighted mean difference = -0.93, 95% confidence interval = -1.56 to -0.30, P = 0.004), postoperative day 2 (weighted mean difference = -1.00, 95% confidence interval = -1.64 to -0.35, P = 0.002), postoperative day 3 (weighted mean difference = -0.92, 95% confidence interval = -1.76 to -0.09, P = 0.03), postoperative day 4 (weighted mean difference = -0.90, 95% confidence interval = -1.24 to -0.56, P < 0.001), and postoperative day 5 (weighted mean difference = -1.39, 95% confidence interval = -2.20 to -0.57, P < 0.001) compared with the placebo transcutaneous electronic nerve stimulation group. No publication bias was found. No significant discovery was obtained in sensitivity analyses. CONCLUSIONS: Transcutaneous electronic nerve stimulation might be an effective supplementary analgesic regimen in multimodal analgesia to decrease pain intensity after pulmonary surgery.

Prognostic value of lymph node ratio in non-small-cell lung cancer: a meta-analysis.

BACKGROUND: This meta-analysis aimed to investigate the prognostic value of lymph node ratio in non-small-cell lung cancer. METHODS: We searched systematically for eligible studies in PubMed, Web of Science, Medline (via Ovid) and Cochrane library through 6 November 2018. The primary outcome was overall survival. Disease-free survival and cancer-specific survival were considered as secondary outcomes. Hazard ratio with corresponding 95% confidence interval were pooled. Quality assessment of included studies was conducted. Subgroup analyses were performed based on N descriptors, types of tumor resection, types of lymphadenectomy and study areas. Sensitivity analysis and evaluation of publication bias were also performed. RESULTS: Altogether, 20 cohorts enrolling 76 929 patients were included. Mean Newcastle-Ottawa Scale was 7.65 ± 0.59, indicating the studies' quality was high. The overall result showed non-small-cell lung cancer patients with lower lymph node ratio was associated with better overall survival (HR: 1.946; 95% CI: 1.746-2.169; P < 0.001), disease-free survival (HR: 2.058; 95% CI: 1.717-2.467; P < 0.001) and cancer-specific survival (HR: 2.149; 95% CI: 1.864-2.477; P < 0.001). Subgroup analysis prompted types of lymphadenectomy and the station of positive lymph node have an important effect on the prognosis. No significant discovery was found in sensitivity analysis. CONCLUSION: Patients with lower lymph node ratio was associated with better survival, indicating that lymph node ratio may be a promising prognostic predictor in non-small-cell lung cancer. The type of lymphadenectomy, an adequate examined number and the removed stations should be considered for more accurate prognosis assessment.