Is the burden of metastatic lymph node stations a prognostic factor in patients with resected lung cancer?

OBJECTIVES

The burden of metastatic lymph node (LN) stations might reflect a distinct N subcategory with a more aggressive biology and behaviour than the traditional N classification.

METHODS

Between 2008 and 2018, we analyzed 1236 patients with pN1/2 lung cancer. Survival was analyzed based on LN station metastasis, determining the optimal threshold for the number of metastatic LN stations that provided additional prognostic information. N prognostic subgrouping was performed using thresholds for the number of metastatic LN stations with the maximum chi-square log-rank value, and validated at each pT-stage.

RESULTS

Survival showed stepwise statistical deterioration with an increase in the number of metastatic LN stations., Threshold values for the number of metastatic LN stations were determined and N prognostic subgroupswas created as sN-alpha; one LN station metastases (n = 632), sN-beta; two-three LN stations metastases (n = 505), and sN-gamma; ≥4 LN stations metastasis (n = 99). The 5-year survival rate was 57.7% for sN-alpha, 39.2% for sN-beta, and 12.7% for sN-gamma (chi-square log rank = 97.906, p < 0.001). A clear tendency of survival deterioration was observed from sN-alpha to sN-gamma in the same pT stage, except for pT4 stage. Multivariate analysis showed that age (p < 0.001), sex (p = 0.002), tumour histology (p < 0.001), IASLC-proposed N subclassification (p < 0.001), and sN prognostic subgroups (p < 0.001) were independent risk factors for survival.

CONCLUSION

The burden of metastatic LN stations is an independent prognostic factor for survival in patients with lung cancer. It could provide additional prognostic information to the N classification.

Validation Study for the N Descriptor of the Newly Proposed Ninth Edition of the TNM Staging System Proposed by the International Association for the Study of Lung Cancer

INTRODUCTION

The aim of this study was to validate the discriminatory ability and clinical utility of the N descriptor of the newly proposed ninth edition of the TNM staging system for lung cancer in a large independent cohort.

METHODS

We retrospectively analyzed patients who underwent curative surgery for NSCLC between January 2004 and December 2019. The N descriptor of patients included in this study was retrospectively reclassified based on the ninth edition of the TNM classification. Survival analysis was performed using the log-rank test and Cox proportional hazard model to compare adjacent N categories.

RESULTS

A total of 6649 patients were included in this study. The median follow-up period was 54 months. According to the newly proposed ninth edition N classification, 5573 patients (83.8%), 639 patients (9.6%), 268 patients (4.0%), and 169 patients (2.5%) were classified into the clinical N0, N1, N2a, and N2b categories and 4957 patients (74.6%), 744 patients (11.2%), 567 patients (8.5%), and 381 patients (5.7%) were classified into the pathologic N0, N1, N2a, and N2b categories, respectively. The prognostic differences between all adjacent clinical and pathologic N categories were highly significant in terms of both overall survival and recurrence-free survival.

CONCLUSIONS

We validated the clinical utility of the newly proposed ninth edition N classification for both clinical and pathologic stages in NSCLC. The new N classification revealed clear prognostic separation between all categories (N0, N1, N2a, and N2b) in terms of both overall survival and recurrence-free survival.

Validation of the 9th edition of the TNM staging system for non-small cell lung cancer with lobectomy in stage IA-IIIA

OBJECTIVES

The 9th edition of tumour-node-metastasis (TNM) staging for lung cancer was announced by Prof Hisao Asamura at the 2023 World Conference on Lung Cancer in Singapore. The purpose of this study was to externally validate and compare the latest staging of lung cancer.

METHODS

We collected 19 193 patients with stage IA-IIIA non-small cell lung cancer (NSCLC) who underwent lobectomy from the Surveillance, Epidemiology and End Results database. Survival analysis by TNM stages was compared using the Kaplan-Meier method and further analysed using univariable and multivariable Cox regression analyses. Receiver operating characteristic curves were used to assess model accuracy, Akaike information criterion, Bayesian information criterion and consistency index were used to compare the prognostic, predictive ability between the current 8th and 9th edition TNM classification.

RESULTS

The 9th edition of the TNM staging system can better distinguish between IB and IIA patients on the survival curve (P < 0.0001). In both univariable and multivariable regression analysis, the 9th edition of the TNM staging system can differentiate any 2 adjacent staging patients more evenly than the 8th edition. The 9th and the 8th edition TNM staging have similar predictive power and accuracy for the overall survival of patients with NSCLC [TNM 9th vs 8th, area under the curve: 62.4 vs 62.3; Akaike information criterion: 166 182.1 vs 166 131.6; Bayesian information criterion: 166 324.3 vs 166 273.8 and consistency index: 0.650 (0.003) vs 0.651(0.003)].

CONCLUSIONS

Our external validation demonstrates that the 9th edition of TNM staging for NSCLC is reasonable and valid. The 9th edition of TNM staging for NSCLC has near-identical prognostic accuracy to the 8th edition.

Lung Cancer Staging: Imaging and Potential Pitfalls

Lung cancer is the leading cause of cancer deaths in men and women in the United States. Accurate staging is needed to determine prognosis and devise effective treatment plans. The International Association for the Study of Lung Cancer (IASLC) has made multiple revisions to the tumor, node, metastasis (TNM) staging system used by the Union for International Cancer Control and the American Joint Committee on Cancer to stage lung cancer. The eighth edition of this staging system includes modifications to the T classification with cut points of 1 cm increments in tumor size, grouping of lung cancers associated with partial or complete lung atelectasis or pneumonitis, grouping of tumors with involvement of a main bronchus regardless of distance from the carina, and upstaging of diaphragmatic invasion to T4. The N classification describes the spread to regional lymph nodes and no changes were proposed for TNM-8. In the M classification, metastatic disease is divided into intra- versus extrathoracic metastasis, and single versus multiple metastases. In order to optimize patient outcomes, it is important to understand the nuances of the TNM staging system, the strengths and weaknesses of various imaging modalities used in lung cancer staging, and potential pitfalls in image interpretation.

Lymph node metastasis in cancer progression: molecular mechanisms, clinical significance and therapeutic interventions

Lymph nodes (LNs) are important hubs for metastatic cell arrest and growth, immune modulation, and secondary dissemination to distant sites through a series of mechanisms, and it has been proved that lymph node metastasis (LNM) is an essential prognostic indicator in many different types of cancer. Therefore, it is important for oncologists to understand the mechanisms of tumor cells to metastasize to LNs, as well as how LNM affects the prognosis and therapy of patients with cancer in order to provide patients with accurate disease assessment and effective treatment strategies. In recent years, with the updates in both basic and clinical studies on LNM and the application of advanced medical technologies, much progress has been made in the understanding of the mechanisms of LNM and the strategies for diagnosis and treatment of LNM. In this review, current knowledge of the anatomical and physiological characteristics of LNs, as well as the molecular mechanisms of LNM, are described. The clinical significance of LNM in different anatomical sites is summarized, including the roles of LNM playing in staging, prognostic prediction, and treatment selection for patients with various types of cancers. And the novel exploration and academic disputes of strategies for recognition, diagnosis, and therapeutic interventions of metastatic LNs are also discussed.

Micropapillary and Solid Histologic Patterns in N1 and N2 Lymph Node Metastases Are Independent Factors of Poor Prognosis in Patients With Stages II to III Lung Adenocarcinoma

INTRODUCTION

High-grade histologic patterns are associated with poor prognosis in patients with primary nonmucinous lung adenocarcinoma (ADC). We investigated whether the presence of micropapillary (MIP), solid (SOL), or both patterns in lymph node (LN) metastases has prognostic value.

METHODS

Patients who underwent lobectomy for pathologic stages II to III lung ADC with N1 or N2 LN metastases (N = 360; 2000-2012) were analyzed. We assessed overall survival (OS), lung cancer-specific cumulative incidence of death (LC-CID), and cumulative incidence of recurrence (CIR) between patients with and without MIP/SOL patterns in LN metastases. Multivariable Cox regression analysis was used to quantify the association between MIP/SOL patterns and outcomes.

RESULTS

MIP and SOL in LN metastases were associated with a higher incidence of smoking history (p = 0.004), tumor necrosis (p = 0.013), and spread of tumor through air spaces (p < 0.0001), a higher prevalence of MIP or SOL in the primary tumor (p < 0.0001), shorter OS (5-y OS, 40% [95% confidence interval or CI: 29%-56%] versus 63% [48%-83%] for no MIP/SOL in LNs, p = 0.03), higher LC-CID (5-y, 43% [29%-56%] versus 14% [4%-29%], p = 0.013), and higher CIR (5-y, 65% [50%-77%] versus 43% [25%-60%], p = 0.057). MIP and SOL in LN metastases were independently associated with poor outcomes: OS (hazard ratio [HR] = 1.81 [95% CI: 1.00-3.29], p = 0.05), LC-CID (HR = 3.10 [1.30-7.37], p = 0.01), and CIR (HR = 2.06 [1.09-3.90], p = 0.026).

CONCLUSIONS

MIP/SOL histologic patterns in N1 or N2 LN metastases are associated with worse outcomes in patients with stages II to III lung ADC. MIP/SOL histologic patterns in LN metastases can stratify patients with high-risk stages II to III lung ADC.

Role of skip N2 lymph node metastasis for patients with the stage III-N2 lung adenocarcinoma: a propensity score matching analysis

PURPOSE

Recent studies have indicated some differences in the prognosis of patients with stage III-N2 lung adenocarcinoma, and the prognosis of patients with skip N2 lymph node metastasis (SKN2) is good. This study grouped patients with stage III-N2 lung adenocarcinoma by propensity score matching (PSM) to evaluate the impact of SKN2 on the prognosis of these patients.

METHODS

The clinical data for patients who underwent radical lobectomy and had a postoperative pathological diagnosis of stage III-N2 lung adenocarcinoma at our centre from 2016 to 2018 were collected, and PSM was performed at a ratio of 1:1.

RESULTS

A total of 456 patients were enrolled in this study. After PSM, 112 patients were included in the SKN2 group, and 112 patients were included in the non-SKN2 group. When comparing the SKN2 group with the non-SKN2 group, the 3-year OS rate was (71.4% vs. 12.5%, p < 0.001), and the 3-year DFS rate was (35.7% vs. 5.4%, p < 0.001). It is further divided into four groups:single-station SKN2 (N2a1),Multi-station SKN2 (N2a2),single-station non-SKN2 (N2b1) and Multi-station non-SKN2 (N2b2).The 3-year OS and DFS rates of skip lymph node metastasis were better than those of non-skip lymph node metastasis(OS:N2a1 vs. N2b1 68.4% vs. 23.5%,p < 0.001;N2a2 vs. N2b2 73.0% vs. 7.7%,p < 0.001)(DFS:N2a1 vs. N2b1 68.4% vs. 5.9%,p < 0.001;N2a2 vs. N2b2 62.2% vs. 5.1%,p < 0.001), regardless of the number of N2 station(OS:N2a1 vs. N2a2 68.4% vs. 73.0%,p = 0.584;N2b1 vs. N2b2 23.5% vs. 7.7%,p = 0.051). On multivariate analysis, sex (p = 0.008) ,Vascular tumour thrombus(p = 0.047),size(p = 0.002)and SKN2 (p < 0.001) were independent predictors of OS.

CONCLUSION

For patients with stage III-N2 lung adenocarcinoma, the prognosis of SKN2 patients is better than non-SKN2 patients', and SKN2 may be used as an important factor in the N2 subgroup classification in future TNM staging.

The International Association for the Study of Lung Cancer Lung Cancer Staging Project: Overview of Challenges and Opportunities in Revising the Nodal Classification of Lung Cancer

The status of lymph node involvement is a major component of the TNM staging system. The N categories for lung cancer have remained unchanged since the fourth edition of the TNM staging system, partly because of differences in nodal mapping nomenclature, partly because of insufficient details to verify possible alternative approaches for staging. In preparation for the rigorous analysis of the International Association for the Study of Lung Cancer database necessary for the ninth edition TNM staging system, members of the N-Descriptors Subcommittee of the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee reviewed the evidence for alternative approaches to categorizing the extent of lymph node involvement with lung cancer, which is currently based solely on the anatomical location of lymph node metastasis. We reviewed the literature focusing on NSCLC to stimulate dialogue and mutual understanding among subcommittee members engaged in developing the ninth edition TNM staging system for lung cancer, which has been proposed for adoption by the American Joint Committee on Cancer and Union for International Cancer Control in 2024. The discussion of the range of possible revision options for the N categories, including the pros and cons of counting lymph nodes, lymph node stations, or lymph node zones, also provides transparency to the process, explaining why certain options may be discarded, others deferred for future consideration. Finally, we provide a preliminary discussion of the future directions that the N-Descriptors Subcommittee might consider for the 10th edition and beyond.

[Review for N2 Sub-staging in Non-small Cell Lung Cancer]

Patients with N2 non-small cell lung cancer (NSCLC) were heterogeneous groups and required further stratification. The International Society for the Study of Lung Cancer (IASLC) divided N2 into three sub-stages: N2 at a single station without N1 involvement (N2a1), N2 at a single station with N1 involvement (N2a2), and N2 at multiple stations (N2b). These new descriptors significantly distinguished the overall survival (OS), disease-free survival (DFS), and recurrence pattern of patients with different N2 sub-stages. The OS and DFS of N2a1 were not sufficiently distinguished from N1 at multiple stations (N1b). The OS and DFS of N2a2 were intermediate between those of N2a1 and N2b. Current evidence did not support the further subdivision of the N2b. The main recurrence pattern of N2a1, N2a2 and N2b were distant metastasis, and the risks of distant metastasis increased successively. N2a1 patients were at low risk of locoregional recurrence, which could not be reduced by postoperative radiotherapy (PORT). N2a2 and N2b patients had a similar higher risk of locoregional recurrence, which could be reduced to a similar level of N2a1 patients by PORT.
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Association of metastatic nodal size with survival in non-surgical non-small cell lung cancer patients: Recommendations for clinical N staging

Background

This study aims to analyze the prognostic significance of the metastatic lymph node (mLN) size in non-small cell lung cancer (NSCLC) patients receiving chemoradiotherapy (CRT) to provide some information for the optimization of clinical nodal (cN) staging.

Methods

A retrospective study with 325 NSCLC patients was conducted between January 2011 and December 2018 at two participating institutes. We evaluated the potential relationship between the mLN size and the survival to propose a potential revised nodal (rN) staging.

Results

Kaplan–Meier analyses showed significant differences in the overall survival (OS) based on the cN staging and the size of mLNs (N0, ≤2 cm, and >2 cm). We found that the nodal size correlated statistically with the response to CRT. The HRs of OS for patients with bulky mLNs increase significantly compared with patients in the non-bulky mLNs group in the cN2-3 group. Interestingly, the HRs of patients with bulky cN2 disease and non-bulky cN3 disease were similar to each other. We classified the patients into five subsets: N0, rN1(cN1), rN2(non-bulky cN2), rN3a(bulky cN2, and non-bulky cN3), and rN3b(bulky cN3). In our study, the rN stage showed better prognostic discrimination than the 8th IASLC cN staging and was an independent prognostic factor for survival.

Conclusions

In addition to the anatomic location, the size of mLNs correlated statistically with the response to CRT and should be incorporated into the cN staging system to predict survival more accurately.

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.

Long-term clinical outcomes and prognostic factors of upfront surgery as a first-line therapy in biopsy-proven clinical N2 non-small cell lung cancer

Background

Multimodality therapy offers the best opportunity to improve pathological N2 non-small cell lung cancer (NSCLC) prognosis. This paper aimed to evaluate the long-term clinical outcomes and the prognostic factors of upfront surgery as first-line therapy in biopsy-proven clinical N2.

Methods

Retrospective review of biopsy-proven cN2 NSCLC patients operated between 2007 and 2017. Upfront surgery was considered if the primary tumour was deemed completely resectable, with mediastinal nodal involvement confined to a single station and no preoperative evidence of extranodal tumour invasion.

Results

Two hundred eighty-five patients who underwent radical resections were included. One hundred fifty-nine patients (55.8%) received induction chemotherapy. At follow-up completion, 127 (44.6%) patients had died. For the induction chemotherapy group, the median overall survival (OS) was 49 months [95% confidence interval (CI): 38–70 months], and the 5-year OS was 44.4%. The median and 5-year OS for the up front surgery group was 66 months (95% CI: 40–119 months) and 66.3%, respectively. There were no statistically significant differences between treatment approaches (p = 0.48). One hundred thirty-four patients (47.0%) developed recurrence. The recurrence-free survival (RFS) at 5 years was 17% (95% CI: 11–25%) for induction chemotherapy and 22% (95% CI: 9–32%) for upfront surgery; there were no statistically significant differences between groups (p = 0.93). No significant differences were observed based on the clinical N status (OS, p = 0.36; RFS, p = 0.65).

Conclusions

Upfront surgery as first-line therapy for biopsy-proven cN2 NSCLC showed favourable clinical outcomes, similar to those obtained after induction chemotherapy followed by surgery. Therefore, it should be considered one of the multimodality treatment options in resectable N2 NSCLC.

Assessment of textbook outcome after lobectomy for early‐stage non‐small cell lung cancer in a Korean institution: A retrospective study

Background

Textbook outcome (TO) has been introduced as a novel composite measure for lung cancer surgery. We investigated TO after lobectomy for early‐stage non‐small cell lung cancer (NSCLC) in a Korean tertiary hospital and its prognostic implications for overall survival and recurrence.

Methods

Between January 2012 and December 2017, 418 consecutive patients who underwent lobectomy for clinical stages I and II NSCLC were identified and retrospectively reviewed. TO was defined as complete resection (negative resection margins and sufficient lymph node dissection), no 30‐day or in‐hospital mortality, no reintervention within 30 days, no readmission to the intensive care unit, no prolonged hospital stay (<14 days), no hospital readmission within 30 days, and no major complications. Propensity score matching analysis was performed to investigate the association between TO, medical costs, and long‐term outcomes.

Results

Of 418 patients, 277 (66.3%) achieved TO. The most common events leading to TO failure were prolonged air leakage (n = 54, 12.9%) and prolonged hospital stay (n = 53, 12.7%). Male sex (odds ratio [OR] = 2.148, p = 0.036) and low diffusing capacity for carbon monoxide (OR = 0.986, p = 0.047) were significant risk factors for failed TO in multivariate analysis. In matched cohorts, achieving TO was associated with lower medical costs and better overall survival but not cancer recurrence.

Conclusions

TO is associated with low medical cost and favorable overall survival; thus, surgical teams and hospitals should make efforts to improve the quality of care and achieve TO.

Anatomical location and number of metastatic lymph nodes for prognosis of non-small cell lung cancer

Background

The nodal classification of lung cancer is determined by the anatomical location of metastatic lymph nodes (mLNs). However, prognosis can be heterogeneous at the same nodal stage, and the current classification system requires improvement. Therefore, we investigated the correlation between the number of mLNs and prognosis in patients with non-small cell lung cancer.

Methods

Using a multicenter database in Japan, we retrospectively reviewed the records of patients who underwent complete resection for lung cancer between 2010 and 2016. Kaplan-Meier curves were used to determine recurrence-free and overall survival. Multivariate analyses were performed using the Cox proportional hazards model.

Results

We included 1,567 patients in this study. We could show a statistically significant difference in recurrence-free survival between pN2 patients with 1 mLN and pN2 patients with ≥2 mLNs (P=0.016). Patients with a combination of pN1 (≥4 mLNs) plus pN2 (1 mLN) had a poorer prognosis than pN1 patients (1-3 mLNs) (P=0.061) and a better prognosis than pN2 patients (≥2 mLNs) patients (P=0.007). Multivariate analysis showed that the number of mLNs was independently associated with cancer recurrence in patients with pN1 and pN2 disease (P=0.034 and 0.018, respectively).

Conclusions

Nodal classification that combines anatomical location and the number of mLNs may predict prognosis more accurately than the current classification system. Our study provides the concept that supports the subdivision of nodal classification in the upcoming revision of the tumor, node, and metastasis staging system.

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.

Does anatomical location-based metastatic lymph node density affect prognosis in lung cancer patients?

 

OBJECTIVES

The newly proposed N subclassification (new-N) was compared with the combined anatomical location and ratio of the number of metastatic lymph nodes to the total number of resected lymph nodes (anatomic-LNR) in terms of prognosis in resected lung cancer patients.

METHODS

Between 2005 and 2018, 961 patients who underwent lung cancer resection were catergorized into the pN1-single (N1a; n = 281), pN1-multiple (N1b; n = 182), pN2-single with skip metastasis (N2a1; n = 116), pN2-single with N1 metastasis (N2a2; n = 222) and pN2-multiple (N2b; n = 160) groups based on new-N. The optimal cut-off points for survival in pN1 and pN2 patients were determined using the best sensitivity and specificity scores, calculated using receiver operating characteristic analysis.

RESULTS

The difference in survival between N1a and N1b patients was statistically significant (P = 0.001), but there was no significant difference in the survival rates of N1b and N2a1 (P = 0.52). The survival curves for N2a1 and N2a2 patients almost overlapped (P = 0.143). N2a2 patients showed a better survival rate than N2b patients, with no significant difference (P = 0.132). The cut-off points for LNR were 0.10 and 0.25 for pN1 and pN2 patients, respectively, according to receiver operating characteristic analysis for survival. Based on receiver operating characteristic analysis, pN patients were categorized into the N1-lowLNR (n = 232), N1-highLNR (n = 231), N2-lowLNR (n = 266) and N2-highLNR (n = 232) groups. The 5-year survival rate was 62.9%, 49.8%, 41.1% and 27.1% for N1-lowLNR, N1-highLNR, N2-lowLNR and N2-highLNR, respectively (P < 0.001).

CONCLUSIONS

LowLNR is associated with better survival than highLNR in resected lung cancer patients. Anatomic-LNR shows a high discriminatory power for prognosis.

Number of metastatic lymph nodes and zones as prognostic factors in non-small-cell lung cancer

OBJECTIVES

Characterizing pathological nodes (pNs) by location alone is sometimes inadequate as patients with pN1 or pN2 non-small-cell lung cancer (NSCLC) show prognostic heterogeneity. We aimed to assess the relationship of the number of metastatic lymph nodes (LNs) and zones with prognosis in NSCLC patients.

METHODS

We analysed 1393 patients who underwent lobectomy with mediastinal LN dissection for NSCLC at the Osaka International Cancer Institute between January 2006 and December 2015. Patients were classified into 3 groups according to the number of LNs: n1-3, n4-6 and n7-. We investigated the relationship of prognosis with the number of metastatic LNs and metastatic zones.

RESULTS

In the multivariable analyses, the number of metastatic LNs and zones were not independent factors for overall survival or recurrence-free survival in patients with pN1 disease after adjustment for age, sex, tumour histology and tumour diameter. However, n4-6 (ref. n1-3) was an independent prognostic factor for overall survival [hazard ratio (HR) 4.148, P < 0.001] in those with pN2 disease. There were no significant differences in overall survival and recurrence-free survival between pN1 (HR 0.674, P = 0.175) and pN2n1-3 disease (HR 1.056, P = 0.808). Moreover, patients with pN2 disease with a higher number of metastatic zones had a poor prognosis for recurrence-free survival [3 zones (ref. 1): HR 1.774, P = 0.051, and 4 zones (ref. 1): HR 2.173, P < 0.047].

CONCLUSIONS

The number of metastatic LNs and metastatic zones were useful prognostic factors in NSCLC patients. The findings could help in establishing a new pN classification.

The addition of radiotherapy to adjuvant chemotherapy has a combinatorial effect in pN2 non-small cell lung cancer only with extranodal invasion or multiple N2 metastasis

OBJECTIVES

The benefit of adjuvant therapy for heterogenous group of pathological N2 (pN2) non-small cell lung cancer (NSCLC) remains unclear. We evaluated the prognostic effect of adjuvant therapy after stratifying patients with pN2 according to subdivided N2 descriptors.

MATERIALS AND METHODS

We performed a retrospective analysis of clinical outcomes in patients with pN2 NSCLC who underwent upfront surgery. N2 descriptors were subdivided as single N2 metastasis without N1 involvement (pN2a1), single N2 with metastasis with N1 involvement (pN2a2), and multiple N2 metastasis (pN2b).

RESULTS

From 2005-2017, 838 patients with pN2 NSCLC underwent complete resection. There were 173 (21.0 %), 338 (40.3 %), and 324 (38.7 %) in the pN2a1, pN2a2, and pN2b groups. Patients who received chemoradiotherapy (CRTx; n = 389, 46.4 %) or chemotherapy (CTx; n = 204, 24.3 %) had similar prognoses, which were better than prognoses in patients who received with radiotherapy (RTx; n = 116, 13.8 %) or those who did not receive adjuvant therapy (n = 129, 15.4 %). According to the stratified multivariable Cox analysis, patients with pN2b stage in the CTx group had a significantly poor prognosis than those in the CRTx group (hazard ratio, 1.38; 95 % confidence interval, 1.03-1.98; p = 0.046). The difference in survival outcomes between the CRTx and CTx groups was significant in patients with extranodal invasion (ENI) (p = 0.011), but not in those without ENI (p = 0.527) CONCLUSIONS: Adjuvant CTx improves the overall and recurrence-free survival in patients with pN2 NSCLC undergoing upfront surgery with complete resection. RTx with adjuvant chemotherapy has a combinatorial effect on pN2 NSCLC only with ENI or multiple N2 metastasis.

A Validation Study of the Recommended Change in Residual Tumor Descriptors Proposed by the International Association for the Study of Lung Cancer for Patients With pN2 NSCLC

INTRODUCTION

This study aimed to validate the residual tumor (R) descriptors proposed by the International Association for the Study of Lung Cancer (IASLC) for patients with pathologic N2 (pN2) NSCLC.

METHODS

We retrospectively reviewed the data of patients with pN2 NSCLC who underwent anatomical resection during the period 2004 to 2018. The R status classified using the Union for International Cancer Control (UICC) criteria was compared with that reassigned using the IASLC criteria. Survival analysis was performed using Cox proportional hazards models to assess the prognostic significance of IASLC R descriptors.

RESULTS

Among 1039 patients, 91.1%, 8.1%, and 0.8% of the patients respectively received complete resection (R0), R1, and R2 defined using the UICC criteria, whereas 41.6%, 20.4%, and 38% respectively received R0, uncertain resection (R[un]), and R1/2 resection defined using the IASLC criteria. Furthermore, 206 patients (21.8%) were reclassified from having UICC R0 to having IASLC R(un) mainly owing to the highest mediastinal lymph node involvement (89.8%). Owing to extracapsular extension, 309 patients (32.6%) with UICC R0 were reclassified as having IASLC R1/2. Patients with IASLC R(un) had significantly worse and better prognosis than those with IASLC R0 and IASLC R1/2, respectively. In multivariable analysis, the prognostic difference between IASLC R0 and R(un) was similar after adjustment for subdivided N2 descriptors including pN2a1, pN2a2, and pN2b.

CONCLUSIONS

Along with subdivided N descriptors, detailed R descriptors proposed on the basis of the IASLC criteria can ensure optimal staging, enabling the most appropriate decision-making on adjuvant therapy for patients with pN2 NSCLC.

The influence of the number of lymph nodes removed on the accuracy of a newly proposed N descriptor classification in patients with surgically-treated lung cancer

INTRODUCTION

The International Association for the Study of Lung Cancer has proposed a new classification of N descriptor based on the number of metastatic lymph nodes (LNs) stations, including skip metastasis. The aim of the study was to determine the effect of removed LNs on the adequacy of this new classification.

MATERIALS AND METHODS

The material was collected retrospectively based on the database of the Polish Lung Cancer Group, including information on 8016 patients with non-small cell lung cancer operated in 23 thoracic surgery centers in Poland. The material covered the period from January 2005 to September 2015. We divided patients into two groups: ≤6LNs and >6LNs removed.

RESULTS

In the whole group, an average of 13.4 nodes and 4.54 nodal stations were removed. 5-year survivals in the >6LNs group vs ≤ 6LNs group were: 62.3% and 55.1% (N0), 44.5% and 35.9% (N1a), 34.1% and 31,7% (N1b), 37.3% and 26.3% (N2a1), 32.4% and 26.7% (N2a2), 29.4% and 29.2% (N2b1), and 22.0% and 23.0% (N2b2), respectively. Comparing these groups, we detected significant differences at N0 (p < 0.001) and N2a1 (p = 0.022). In the ≤6LNs group, the survival curves for N2a1, N2a2, N2b1, and N2b2 overlapped (p > 0.05). In the >6LNs group, the survival curves were significantly different between grades, with survival for N2a1 better than N1b (p = 0.232).

CONCLUSION

The proposed classification N descriptor is potentially better at differentiating patients into different stages. The accuracy of the classification depends on the number of lymph nodes removed. Therefore, the extent of lymphadenectomy has a significant impact on the staging of surgically-treated lung cancer.

Validation of the 8th Edition Nodal Staging and Proposal of New Nodal Categories for Future Editions of the TNM Classification of Non-Small Cell Lung Cancer

BACKGROUND

The International Association for the Study of Lung Cancer (IASLC) N classifications, which depend on the location and involvement of the lymph nodes, provide accurate prognoses. This study validated the efficiency of classifications using a single-institution dataset and proposed a modified system based on 5-level N1 node dissection.

METHODS

From January 2005 to December 2014, 1851 patients with completely resected non-small cell lung cancer were reviewed. According to the IASLC recommendations, N1 is further subdivided into N1a (single) and N1b (multiple), N2 is divided into N2a1 (single station without N1), N2a2 (single station with N1), and N2b (multiple station). Additionally, we evaluated dividing N0 into N0a (with level 13/14 examination) and N0b (without level 13/14 examination), and N1 into N1a* (only level 13/14 positive) and N1b* (level 10-12 positive). Overall survival was also compared.

RESULTS

Multivariate analysis showed that the N classifications recommended by the IASLC and those proposed and evaluated by this study could both significantly predict the prognoses of patients (p < 0.001, respectively). There was no significant difference in survival between N1b and N1a (hazard ratio [HR] 1.049, p = 0.83) and N2a1 and N1b (HR 1.314, p = 0.261); however, there were significant differences between N0a and N0b (HR 1.778, p < 0.001) and N1a* and N1b* (HR 2.014, p = 0.019). The survival curve of N1a* overlapped N0b (HR 0.997, p = 0.991), and N2a1 overlapped N1b* (HR 0.842, p = 0.444).

CONCLUSION

More detailed nodal information is required to facilitate future revisions of N staging.

Which N Descriptor Is More Predictive of Prognosis in Resected Non-small Cell Lung Cancer: The Number of Involved Nodal Stations or the Location-Based Pathological N Stage?

BACKGROUND

The eighth edition of nodal classification for non-small cell lung cancer (NSCLC) is defined only by the anatomical location of metastatic lymph nodes.

RESEARCH QUESTION

We sought to evaluate the prognostic significance and discriminatory capability of the number of involved nodal stations (nS) in a large Chinese cohort.

STUDY DESIGN AND METHODS

A total of 4,011 patients with NSCLC undergoing surgical resection between 2009 and 2013 were identified. The optimal cutoff values for nS classification were determined with X-tile software. Kaplan-Meier and multivariate Cox analysis were used to examine the prognostic performance of nS classification in comparison with location-based N classification. A decision curve analysis was performed to evaluate the standardized net benefit of nS classification in predicting prognosis.

RESULTS

All the patients were classified into four prognostically different subgroups according to the number of involved nodal stations: (1) nS0 (none positive), (2) nS1 (one involved station), (3) nS2 (two involved stations), and (4) nS ≥ 3 (three or more involved stations). The prognoses among all the neighboring categories of nS classification were statistically significantly different in terms of disease-free survival and overall survival. The multivariate Cox analysis demonstrated that nS was an independent prognostic factor of disease-free survival and overall survival. Patients with N1 or N2 stage disease could be divided into three prognostically different subgroups according to nS classification. However, the prognosis was similar between the N1 and N2 subgroups when patients were staged in the same nS category. The decision curve analysis showed that nS classification tended to have a higher predictive capability than location-based N classification.

INTERPRETATION

The nS classification could be used to provide a more accurate prognosis for patients with resected NSCLC. The nS is worth taking into consideration when defining nodal category in the forthcoming ninth edition of the staging system.

Postoperative long-term survival of non-small cell lung cancer patients with skip-N2 metastases

OBJECTIVE

Radical lymphadenectomy is crucial in operations for non-small cell lung cancer (NSCLC). Usually pN1 and pN2 lymph nodes are affected consecutively (N1N2). Nevertheless, pN2 metastases may also occur in the absence of pN1 as skip-N2 metastases (N0N2). Here we compare the long-term survival of N1N2- and N0N2 patients.

MATERIALS AND METHODS

464 patients underwent surgery for NSCLC at our institution between 2012 and 2017. We retrospectively reviewed data of pN2 stage patients (n = 68). Patients with N1N2 (n = 39) were compared to N0N2 (n = 29) patients. 1-, 3-and 5-year survival rates were measured. Survival was assessed by Kaplan-Meier curves and the cox proportional hazards model was used to identify prognostic factors for overall survival. All patients received adjuvant chemoradiation therapy according to European guidelines.

RESULTS

The baseline characteristics did not differ between groups. We observed no differences in the histology, localization, or gender in our cohort. N0N2 patients showed significantly better 1- (N1N2: 82.4% vs. N0N2 100%; p = 0.001), 3- (14.7% vs. 63.6%; p=<0.001) and 5-year (9.4% vs. 43.8%; p = 0.001) survival rates. Tumor size (Hazard ratio (HR) 1.46, Confidence interval (CI 95%) 1.03-2.04; p = 0.03) and the occurrence of N1N2 (HR 4.26, CI 2.04-8.91; p < 0.0001) were independent prognostic factors for worse long-term survival. The Kaplan-Meier curves showed a reduced overall survival for N1N2 patients (log-rank N1N2, N0N2 p < 0.0001).

CONCLUSION

N1N2 patients have a significantly worse prognosis compared to N0N2 patients. This will aid to classify the heterogeneous pN2-NSCLC patient population more precisely. Further, multimodal therapy should be considered for N1N2 patients.

New N1/N2 classification and lobe specific lymphatic drainage: Impact on survival in patients with non-small cell lung cancer treated with surgery

OBJECTIVE

to validate the proposed N descriptor revision on a large cohort of patients and assess the impact of tumour location on the distribution pattern of lymph node metastases for patients with NSCLC.

METHODS

This is a retrospective review of a consecutive series of patients who had anatomical lung resections. Systematic lymph node dissection was done for all patients.

RESULTS

Between January 2009 and December 2019 2566 patients had surgical resection for NSCLC. 448 patients (17.5%) had histologically confirmed lymph node metastases: 257 (57.4 %) had pN1 and 191 pN2. Median age of the study population was 69.1 years. Overall survival (OS) for study population was 37.3 months with 5-year survival rate of 35.7 %. The survival analysis of the N subgroups showed the pN2 patients had a median OS of 27.9 months vs. 41.7 months for pN1 patients (p = 0.013). Analysis as per the new proposal of the N subgroups N1a vs N1b vs N2a1 vs N2a2 vs N2b showed that median survival OS was 41.7 vs. 39.2 mo vs. 33.3 mo vs. 28.9 mo vs. 24.6 mo (p = 0.099). There was statistically significant difference in survival between N2 patients with skip metastasis and N2 patients without skip metastases: OS 32.2 (95 % CI: 16.8-47.6) months vs. 24.2 months (p = 0.024). On multivariate analysis only pathological N (p = 0.011) and the new proposed N classification (p = 0.006) were independent prognostic factors for survival.

CONCLUSIONS

N1 and N2 disease are heterogeneous groups and require further stratification. The number of N2 lymph node stations involved and the presence or not of N1 disease translated to significant differences in survival and therefore have to be included in N staging.

Alternative methods of lymph node staging in lung cancer: a narrative review

The nodal status indicator in non-small cell lung cancer is one of the most crucial prognostic factors available. However, there are still many arguments among scientists regarding whether the currently used nodal status descriptor should be changed in the forthcoming editions of the Tumor Node Metastasis classification or whether it is precise enough and should be maintained as is. We reviewed studies concerning nodal factor classifications to evaluate their accuracy in non-small cell lung cancer patients and to address the previously mentioned challenge. We reviewed the PubMed database regarding the following classifications: ongoing 8^th edition of the Tumor Node Metastasis classification, number of positive lymph nodes, number of negative lymph nodes, number of dissected lymph nodes, lymph node ratio, nodal chains, log odds of positive lymph nodes, zone-based classification and one that is based on the number of lymph node stations involved. Moreover, we analysed data regarding various combinations of these classifications. Our analysis showed that the present nodal staging may not accurately categorize every lung cancer patient. The number of positive lymph nodes and lymph node ratio or the log odds of positive lymph nodes (as the mathematical modification of lymph node ratio) are more legitimate, as they possess very robust data and should be considered initially as additional factors that can be incorporated in ongoing nodal staging systems. Forthcoming non-small cell lung cancer staging systems could benefit from the addition of quantitative-based parameters. Additionally, the minimal extent of lymphadenectomy should be established as staging benefits from it. International, prospective validation studies need to be performed to optimize the cut-off values and prognostic groups and to confirm the superiority of the newly suggested descriptors in non-small cell lung cancer nodal staging.

Prognostic impact of the number of involved lymph node stations in patients with completely resected non-small cell lung cancer: a proposal for future revisions of the N classification

OBJECTIVE

The current nodal staging for lung cancer is defined only by the anatomical site of metastasis. However, the International Association for the Study of Lung Cancer (IASLC) proposed further subdivisions of the N descriptor that considers the locations and numbers of involved lymph node stations. This study aimed to test the new IASLC categories and compare their prognostic abilities to those of our proposed model that considers only the number of involved lymph node stations instead of the sites of metastasis.

METHODS

Between September 2002 and December 2016, 1581 patients who underwent complete resection for pathologically diagnosed Tis-4N0-2M0 non-small cell lung cancer were retrospectively analyzed. We evaluated the survival rates according to the patients' N classification as recently proposed by the IASLC and by the number of involved lymph node stations, and determined the optimal N classification.

RESULTS

The 5-year survival rates for patients with IASLC stages N1a, N1b, N2a1, N2a2, and N2b were 71.5%, 49.9%, 73.7%, 62.1%, and 46.9%, respectively. These results showed relatively good categorizations; however, some prognostic overlaps existed and not all differences were significant. After redefining the number of involved stations as Nα for 1, Nβ for 2-3, and Nγ for ≥ 4 without considering the metastasis sites, the 5-year survival rates for patients in these categories were 72.1%, 58.3%, and 29.6%, respectively; the differences between them were significant.

CONCLUSION

The number of involved lymph node stations is a more accurate prognostic indicator in patients with completely resected non-small cell lung cancer.