Define relative incomplete resection by highest mediastinal lymph node metastasis for non-small cell lung cancers: rationale based on prognosis analysis

Uncertain Resection in Lung Cancer: A Comprehensive Review of the International Association for the Study of Lung Cancer Classification

Objective: We explored the impact of uncertain resection in lung cancer on overall survival and disease-free survival. Methods: We performed an exhaustive literature review of all studies comparing prognosis after resection according to the IASLC classification, from the PubMed, Cochrane, MEDLINE, and Google Scholar databases. Results: Overall, 68 original studies were included, of which 67 were retrospective and 1 was prospective, with 81 785 patients included over 46 years. R(un) reclassification was mostly caused by a lack of hilar or mediastinal node dissection, or because of metastasis in the highest node. R(un) is a strong factor for higher recurrence and mortality, while its effects seem limited in early stages. Carcinoma in situ at bronchial margin resection (CIS BRM) does not show an effect on survival, while positive pleural cytology (Cy+) and positive highest mediastinal lymph node (HMLN+) appear to be highly predictive of recurrence and death. Discussion: The R(un) classification of the IASLC appears highly relevant, especially in locally advanced stages IIb-IIIA, and helps to discriminate patients with poor prognosis despite being classified as R0 in the UICC classification. Conclusions: The use of this more precise classification would allow for better stratification of recurrence risk and more effective use of adjuvant therapies. Cy+ patients should receive adjuvant chemotherapy, while CIS BRM patients could likely benefit from endoscopic surveillance to detect local recurrences. HMLN+ patients should be considered at high risk of recurrence, and adjuvant radio-chemotherapy should be considered.

Impact of mediastinal tumor burden and lymphatic spread in locally advanced non-small-cell lung cancer: A secondary analysis of the multicenter randomized PET-Plan trial

PURPOSE

The aim of this secondary analysis of the prospective randomized phase 2 PET-Plan trial (ARO-2009-09; NCT00697333) was to evaluate the impact of mediastinal tumor burden and lymphatic spread in patients with locally advanced non-small-cell lung cancer (NSCLC).

METHODS

All patients treated per protocol (n = 172) were included. Patients received isotoxically dose-escalated chemoradiotherapy up to a total dose of 60-74 Gy in 30-37 fractions, aiming as high as possible while adhering to normal tissue constraints. Radiation treatment (RT) planning was based on an 18F-FDG PET/CT targeting all lymph node (LN) stations containing CT positive LNs (i.e. short axis diameter > 10 mm), even if PET-negative (arm A) or targeting only LN stations containing PET-positive nodes (arm B). LN stations were classified into echelon 1 (ipsilateral hilum), 2 (ipsilateral station 4 and 7), and 3 (rest of the mediastinum, contralateral hilum). The endpoints were overall survival (OS), progression-free survival (PFS), and freedom from local progression (FFLP).

RESULTS

The median follow-up time (95 % confidence interval [CI]) was 41.1 (33.8 - 50.4) months. Patients with a high absolute number of PET-positive LN stations had worse OS (hazard ratio [HR] = 1.09; 95 % CI 0.99 - 1.18; p = 0.05) and PFS (HR = 1.12; 95 % CI 1.04 - 1.20; p = 0.003), irrespective of treatment arm allocation. The prescribed RT dose to the LNs did not correlate with any of the endpoints when considering all patients. However, in patients in arm B (i.e., PET-based selective nodal irradiation), prescribed RT dose to each LN station correlated significantly with FFLP (HR=0.45; 95 % CI 0.24-0.85; p = 0.01). Furthermore, patients with involvement of echelon 3 LN stations had worse PFS (HR = 2.22; 95 % CI 1.16-4.28; p = 0.02), also irrespective of allocation.

CONCLUSION

Mediastinal tumor burden and lymphatic involvement patterns influence outcome in patients treated with definitive chemoradiotherapy for locally advanced NSCLC. Higher dose to LNs did not improve OS, but did improve FFLP in patients treated with PET-based dose-escalated RT.

Prognostic Significance of the Highest Mediastinal Lymph Node Involvement in Patients with Stage III-N2 Non-small Cell Lung Cancer

BACKGROUND

Highest mediastinal lymph node (HMLN) involvement is a category of uncertain resection, yet the prognostic significance of HMLN involvement remains controversial.

METHODS

A total of 486 patients with pathological stage III-N2 disease who underwent radical resection were enrolled from January 2015 to December 2018. Patients were allocated into two groups-HMLN involvement (219 cases) and HMLN-negative (249 cases) groups. Kaplan-Meier analysis and Cox proportional hazard regression models were used to evaluate the impact of HMLN involvement on 5-year recurrence-free survival (RFS) and overall survival (OS).

RESULTS

The proportion of patients with multiple N2 diseases (72.1% vs. 23.7%; p < 0.001) and stage IIIA (87.2% vs. 77.5%; p < 0.009) were greater in the HMLN-involvement group than in the HMLN-negative group, and the survival rates of the HMLN-involvement group were significantly lower than those of the HMLN-negative group (RFS: 27.2% vs. 49.8%, p < 0.001; OS: 42.1% vs. 59.2%, p = 0.001). HMLN status was an independent factor for OS only (RFS: adjusted hazard ratio [aHR] 1.26, 95% confidence interval CI 0.94-1.68; OS: aHR 1.45, 95% CI 1.07-1.99) in the entire stage III cohort. After stratification of patients according to stage, the involvement of HMLN decreased both RFS and OS in the stage IIIA group (RFS: aHR 1.46, 95% CI 1.06-2.02; OS: aHR 1.70, 95% CI 1.19-2.42); however, no such difference was observed within the stage IIIB group.

CONCLUSIONS

HMLN involvement is a prognostic factor of deteriorating survival in highly advanced N2 disease only in patients with stage IIIA.

The International Association for the Study of Lung Cancer Lung Cancer Staging Project: Proposals for Revision of the Classification of Residual Tumor After Resection for the Forthcoming (Ninth) Edition of the TNM Classification of Lung Cancer

INTRODUCTION

The goal of surgical resection is to completely remove a cancer; it is useful to have a system to describe how well this was accomplished. This is captured by the residual tumor (R) classification, which is separate from the TNM classification that describes the anatomic extent of a cancer independent of treatment. The traditional R-classification designates as R0 a complete resection, as R1 a macroscopically complete resection but with microscopic tumor at the surgical margin, and as R2 a resection that leaves gross tumor behind. For lung cancer, an additional category encompasses situations in which the presence of residual tumor is uncertain.

METHODS

This paper represents a comprehensive review of evidence regarding these R categories and the descriptors thereof, focusing on studies published after the year 2000 and with adjustment for potential confounders.

RESULTS

Consistent discrimination between complete, uncertain, and incomplete resection is revealed with respect to overall survival. Evidence regarding specific descriptors is generally somewhat limited and only partially consistent; nevertheless, the data suggest retaining all descriptors but with clarifications to address ambiguities.

CONCLUSION

On the basis of this review, the R-classification for the ninth edition of stage classification of lung cancer is proposed to retain the same overall framework and descriptors, with more precise definitions of descriptors. These refinements should facilitate application and further research.

The additional radiotherapy to adjuvant chemotherapy improves the prognosis of stage III-N2 with highest mediastinal lymph node metastasis in non-small cell lung cancer

INTRODUCTION

The benefits of adjuvant chemoradiation therapy (CRT) for heterogeneous pathological N2 (pN2) diseases remain unclear in non-small cell lung cancer (NSCLC). This study aimed to investigate suitable pN2 patients for adjuvant CRT.

MATERIAL AND METHODS

This study retrospectively reviewed the data of patients with pN2 NSCLC in Shanghai Pulmonary Hospital from January 2012 to December 2016. Included cases were subdivided as highest mediastinal lymph node (HM) (n = 732) metastasis and non-HM metastasis (n = 677) groups according to the International Association for the Study of Lung Cancer (IASLC). Furthermore, the Kaplan-Meier and Cox models were used to evaluate the prognostic benefits of adjuvant CRT in heterogeneous pN2 subgroups.

RESULTS

A total of 1409 patients were enrolled in this study, with a median follow-up time of 63.8 months. Patients with HM involvement had worse prognoses (p < 0.001 for recurrence-free survival (RFS) and overall survival (OS)). Furthermore, the survival improvement of adjuvant CRT was significant for these patients (p < 0.001 for RFS and p = 0.032 for OS), regardless of whether it was single (p < 0.001 for RFS and p = 0.029 for OS) or multiple pN2 (p < 0.001 for RFS and p = 0.026 for OS) diseases. According to multivariable cox analysis, the long-term RFS and OS in the cancerous HM group were independently predicted by pathological N stage (p = 0.002 for RFS and p < 0.001 for OS) and adjuvant CRT (p < 0.001 for RFS and p = 0.011 for OS).

CONCLUSION

Metastatic HM was associated with a worse prognosis in pN2 disease. Our analysis supported that adjuvant CRT significantly improved both RFS and OS for these patients.

Prognostic significance of uncertain resection for metastasis in the highest mediastinal lymph node after surgery for clinical N0 non-small cell lung cancer

Background

The International Association for the Study of Lung Cancer defined types of surgical resection and considered the positivity of the highest mediastinal lymph node resected a parameter of "uncertain resection" (R-u). We investigated the metastases in the highest mediastinal lymph node, defined as the lowest numerically numbered station among those resected. We aimed to evaluate the prognostic value of R-u compared with R0.

Materials and methods

We selected 550 patients with non-small cell lung cancer at clinical Stage I, IIA, IIB (T3N0M0), or IIIA (T4N0M0) undergoing lobectomy and systematic lymphadenectomy between 2015 and 2020. The R-u group included patients with positive highest mediastinal resected lymph node.

Results

In the groups of patients with mediastinal lymph node metastasis, we defined 31 as R-u (45.6%, 31/68). The incidence of metastases in the highest lymph node was related to the pN2 subgroups (p < 0.001) and the type of lymphadenectomy performed (p < 0.001). The survival analysis compared R0 and R-u: 3-year disease-free survival was 69.0% and 20.0%, respectively, and 3-year overall survival was 78.0% and 40.0%, respectively. The recurrence rate was 29.7% in R0 and 71.0% in R-u (p-value < 0.001), and the mortality rate was 18.9% and 51.6%, respectively (p-value < 0.001). R-u variable showed a tendency to be a significant prognostic factor for disease-free survival and overall survival (hazard ratio: 4.6 and 4.5, respectively, p-value < 0.001).

Conclusions

The presence of metastasis in the highest mediastinal lymph node removed seems to be an independent prognostic factor for mortality and recurrence. The finding of these metastases represents the margin of cancer dissemination at the time of surgery, so it could imply metastasis into the N3 node or distant metastasis.

Validation of the IASLC Residual Tumor Classification in Patients With Stage III-N2 Non-Small Cell Lung Cancer Undergoing Neoadjuvant Chemoradiotherapy Followed By Surgery

OBJECTIVE

The aim of this study was to validate the International Association for the Study of Lung Cancer (IASLC) residual tumor classification in patients with stage III-N2 non-small cell lung cancer (NSCLC) undergoing neoadjuvant concurrent chemoradiotherapy (nCCRT) followed by surgery.

BACKGROUND

As adequate nodal assessment is crucial for determining prognosis in patients with clinical N2 NSCLC undergoing nCCRT followed by surgery, the new classification may have better prognostic implications.

METHODS

Using a registry for thoracic cancer surgery at a tertiary hospital in Seoul, Korea, between 2003 and 2019, we analyzed 910 patients with stage III-N2 NSCLC who underwent nCCRT followed by surgery. We classified resections using IASLC criteria: complete (R0), uncertain (R[un]), and incomplete resection (R1/R2). Recurrence and mortality were compared using adjusted subdistribution hazard model and Cox-proportional hazards model, respectively.

RESULTS

Of the 96.3% (n = 876) patients who were R0 by Union for International Cancer Control (UICC) criteria, 34.5% (n = 3O2) remained R0 by IASLC criteria and 37.6% (n = 329) and 28% (n = 245) migrated to R(un) and R1, respectively. Most of the migration from UICC-R0 to lASLC-R(un) and IASLC-R1/R2 occurred due to inadequate nodal assessment (85.5%) and extracapsular nodal extension (77.6%), respectively. Compared to R0, the adjusted hazard ratios in R(un) and R1/R2 were 1.20 (95% confidence interval, 0.94-1.52), 1.50 (1.17-1.52) ( P fortrend = .001) for recurrence and 1.18 (0.93-1.51) and 1.51 (1.17-1.96) for death ( P for trend = .002).

CONCLUSIONS

The IASLC R classification has prognostic relevance in patients with stage III-N2 NSCLC undergoing nCCRT followed by surgery. The IASLC classification will improve the thoroughness of intraoperative nodal assessment and the completeness of resection.

Propensity-Matched Analysis of Clinical Relevance of the Highest Mediastinal Lymph Node Metastasis

BACKGROUND

The clinical relevance of the highest mediastinal lymph node (HMLL) metastasis in patients with pathological N2 non-small cell lung cancer (NSCLC) is still controversial. Our study aimed to reassess the effect of HMLL metastasis on survival.

METHODS

Patients with stage pT1-4N2M0 NSCLC who underwent major lung resection and systemic lymphadenectomy at Peking University People's Hospital from 2004 to 2015 were identified. Patients in the HMLL-positive group were matched to patients in the HMLL-negative group using 1:1 propensity score matching analysis. Overall survival was estimated by Kaplan-Meier method and compared using log-rank test, and multivariable Cox proportional hazard regression was constructed to identify risk factors associated with overall survival. The cumulative incidence of cancer specific mortality was evaluated through a competing risk analysis.

RESULTS

A total of 266 NSCLC patients with stage pT1-4N2M0 NSCLC were enrolled. Of those, 128 cases were HMLL positive and 138 cases were HMLL negative. A higher proportion of patients in the HMLL-positive group were female (P = .034) and had a higher rate of adenocarcinoma (P = .003). Compared with the HMLL-negative, the HMLL-positive group was not associated with worse survival in unmatched cohorts (adjusted hazard ratio = 1.21; 95% confidence interval, 0.87-1.68). After propensity score matching, 109 pairs were selected. No survival difference remained in matched cohorts (adjusted hazard ratio = 1.00; 95% confidence interval, 0.70-1.42).

CONCLUSIONS

Highest mediastinal lymph node metastasis does not exhibit worse survival in patients with stage pT1-4N2M0 NSCLC. The clinical relevance of HMLL metastasis needs further examination.

[Correlation between Lymph Node Ratio and Clinicopathological Features and Prognosis of IIIa-N2 Non-small Cell Lung Cancer]

BACKGROUND

IIIa-N2 non-small cell lung cancer was significant different in survival, although N stage of lung cancer based on anatomic location of metastasis lymph node. Lymph node ratio considered of prognostic factor might be the evaluation index for IIIa-N2 non-small cell lung cancer prognosis. Therefore, the aim of the study was to evaluate the correlation between lymph node ratio and clinicopathological features and prognosis of IIIa-N2 non-small cell lung cancer prognosis.

METHODS

A total of 288 cases of pathological IIIa-N2 non-small cell lung cancer were enrolled who received radical resection at the Department of Thoracic Surgery II, Peking University Cancer Hospital from January 2006 to December 2016. The univariate analysis between clinicopathological variables and lymph node ratio used Pearson's chi-squared test. Cox regression was conducted to identify the independent prognosis factors for IIIa-N2 non-small cell lung cancer.

RESULTS

There were 139 cases in the lower lymph node ratio group, another 149 cases in the higher lymph node ratio group. Adenocarcinoma (χ²=5.924, P=0.015), highest mediastinal lymph node metastasis (χ²=46.136, P<0.001), multiple-number N2 metastasis (χ²=59.347, P<0.001), multiple-station N2 metastasis (χ²=77.387, P<0.001) and skip N2 lymph node metastasis (χ²=61.524, P<0.001) significantly impacted lymph node ratio. The total number of lymph node dissection was not correlated with the lymph node ratio (χ²=0.537, P=0.464). Cox regression analysis confirmed that adenocarcinoma (P=0.008), multiple-number N2 metastasis (P=0.025) and lymph node ratio (P=0.001) were the independent prognosis factors of disease free survival. The 5-year disease free survival was 18.1% in the higher lymph node ratio group, and 44.1% in the lower. Lymph node ratio was the independent prognosis factor of overall survival (P<0.001). The 5-year overall survival was 36.7% in the higher lymph node ratio group, and 64.1% in the lower.

CONCLUSIONS

Lymph node ratio was correlative with the pathology, highest mediastinal lymph node metastasis, multiple-number N2 metastasis, multiple-station N2 metastasis and skip N2 lymph node metastasis. Lymph node ratio was the independent prognosis factor for IIIa-N2 non-small cell lung cancer.

Accidental invisible intrathoracic disseminated pT4-M1a: a distinct lung cancer with favorable prognosis

OBJECTIVE

In the 7(th) edition of the TNM classification of malignant tumors, the prognosis for pT4-M1a stage IV lung cancer is better than for stage pIIIB. Subgroups of lung cancer patients who underwent incomplete resection (R1/R2) have a favorable prognosis. This study compares the prognosis between cases of invisible local residual disease and intrathoracic disseminated pT4-M1aIV.

METHODS

Patient characteristics and histological and molecular profiles were retrospectively collected for lung cancer patients who underwent resection intended to be curative but were accidentally incomplete. All patients were divided into either a local residual group or an intrathoracic disseminated pT4M1a group. Progression-free survival (PFS) and overall survival (OS) were evaluated by Kaplan-Meier and Cox regression models.

RESULTS

In total, 1,483 consecutive lung cancer patients receiving thoracotomies at Guangdong Lung Cancer Institute were retrospectively analyzed. Fifty-eight patients receiving incomplete resections (R1/R2) were enrolled, including 38 patients with local residual cancer (2.6% of all patients) and 20 patients with disseminated pM1a (1.3%). Patient characteristics, and histological and molecular profiles of the two groups were different. Compared to the local residual group, the disseminated pT4-M1a group contained more females (P=0.002), more patients younger than 60 years of age (P=0.028), more non-smokers (P=0.037), more adenocarcinomas (20/20 vs. 20/38, P<0.001), more adenocarcinomas with lepidic pattern (11/20 vs. 4/38, P<0.001), higher carcinoembryonic antigen (CEA) levels (P=0.06), higher epidermal growth factor receptor (EGFR) mutation rates (16/20 vs. 7/38, P<0.001), a higher R2/R1 resection ratio (P=0.013), a higher advanced stage IV/IIIB ratio (P<0.001), but fewer lymph node metastases (P=0.013). Median PFS for the local residual and disseminated pT4-M1a groups was 9.0 and 18.0 months, respectively [95% confidence interval (CI), 5.285-16.715; P =0.099]. Median OS was 15.0 and 45.0 months, respectively (95% CI, 18.972-39.028; P=0.001). Cox regression analysis revealed that group (local residual vs. disseminated pT4-M1a) was the only independent prognostic factor (P=0.044) for OS.

CONCLUSIONS

Accidental invisible intrathoracic disseminated pT4-M1a may be a distinct lung cancer subtype with a favorable prognosis. The prolonged PFS and OS might reflect the natural history of this distinct subtype, together with a favorable response to EGFR tyrosine kinase inhibitors (EGFR-TKI). For asymptomatic and slow-growing accidental pT4-M1a disease, the role of a wait-and-see strategy and the appropriate timing of systemic treatment require further investigation.

Treatment outcomes of patients with different subtypes of large cell carcinoma of the lung

BACKGROUND

Although large cell neuroendocrine carcinoma (LCNEC) and lymphoepithelioma-like carcinoma (LELC) are the variants of large cell carcinoma (LCC) of lung, there are few studies comparing them. The aim of this study was to compare the clinical characteristic and treatment outcomes of LCNEC, LELC, and classic LCC.

METHODS

Patients with LCNEC, LELC, or classic LCC were identified in a prospectively collected database, and their data were analyzed.

RESULTS

A total of 46 patients with classic LCC, 30 with LCNEC, and 18 with LELC, who received surgical resection with curative intent, were identified and included in the analysis. Patients with LELC were younger, and the frequency of nonsmokers was greater than in patients with classic LCC or LCNEC. In patients with LCNEC or LELC, most lesions were located on the left side. There were 5 surgical deaths, and the median follow-up time of the surviving patients was 44.1 months. The 5-year disease free survival among the three subgroups was similar (p = 0.601), but patients with LELC had a significantly better overall survival than the other two subgroups (LELC vs classic LCC, p = 0.009; LELC vs LCNEC, p = 0.002). Multivariate analysis showed tumor location site, tumor stage, and LELC were independent prognostic factors of overall survival.

CONCLUSIONS

The clinical manifestations and treatment outcomes of LCNEC, LELC, and classic LCC are different. LCNEC has a poor survival, and survival is not different than that of classic LCC. LELC is associated with younger age and a higher frequency of nonsmokers, and the treatment outcomes are better than those of other subtypes.

The Prognosis According to Patterns of Mediastinal Lymph Node Metastasis in Pathologic Stage IIIA/N2 Non-Small Cell Lung Cancer

Background

The aim of this study is to evaluate prognostic factors for survival in pathologic stage IIIA/N2 non-small-cell lung cancer (NSCLC), to identify the prognostic significance of the metastatic patterns of mediastinal lymph nodes (MLNs) relating to survival and to recurrence and metastasis.

Methods

A total of 129 patients who underwent radical resection for pathologic stage IIIA-N2 NSCLC from July 1998 to April 2011 were retrospectively reviewed. The end points of this study were rates of loco-regional recurrence and distant metastasis, and survival.

Results

The overall 5-year survival rate was 47.4%. A univariate analysis showed that age, pathologic T stage, and adjuvant chemotherapy were significant prognostic factors, while in multivariate analysis, pathologic T stage and adjuvant chemotherapy were significant prognostic factors. The metastasis rate was higher in patients with multistation N2 involvement and with more than 3 positive MLNs. Further, non-regional MLN metastasis was associated with a higher loco-regional recurrence rate.

Conclusion

Pathologic T stage and adjuvant chemotherapy were independent prognostic factors for long-term survival in pathologic stage IIIA/N2 NSCLC. The recurrence and the metastasis rate were affected by the metastatic patterns of MLNs. These results may be helpful for planning postoperative therapeutic strategies and predicting outcomes.

Evaluation of dynamic change of serum miR-21 and miR-24 in pre- and post-operative lung carcinoma patients

Although circulating microRNAs (miRNAs) were frequently detected in sera of cancer patients, there is still a lack of analysis of the dynamic changes of miRNAs expression in sera of pre- and post-operative lung carcinoma patients. Thus, we conducted quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to examine the expression of four miRNAs (miR-21, miR-205, miR-30d, and miR-24) in the sera of a set of 82 pre-operative lung carcinoma patients and paired 10 days post-operative patients, as well as in 50 normal volunteers. We showed that, compared to that in normal volunteers, the expression of miR-21, miR-205, miR-30d, and miR-24 was increased in lung cancer sera samples, as well as in sera of early stage lung cancer patients according to their clinical-pathological characteristics. The area under roc curves (AUCs) for levels of miR-21, miR-205, miR-30d, and miR-24 in sera were significantly higher than those for Carcinoma embryonic antigen (CEA) (P < 0.05), whereas the AUC for combination of serum levels of miRNA with serum CEA showed no significant difference from that for serum levels of miRNAs only (P > 0.05). The expression levels of miR-21 and miR-24 were significantly decreased in post-operative sera compared with levels in paired pre-operative sera (P = 0.0004 and <0.0001, respectively). In addition, high expressions of miR-21 and miR-30d in pre-operative sera were independently correlated with shorter overall survival in lung cancer patients (log-rank test: P = 0.0498, 0.0019). In summary, our results suggest that miR-21, miR-205, miR-30d, and miR-24 may serve as potential novel non-invasive biomarkers for diagnosis of lung cancer. In addition, miR-21 and miR-24 serum levels were lower in post-operative samples than those in pre-operative samples, suggesting they can potentially be used as biomarkers for disease recurrence after surgery operation.

Re-appraisal of N2 disease by lymphatic drainage pattern for non-small-cell lung cancers: by terms of nodal stations, zones, chains, and a composite

PURPOSE

N2 non-small-cell lung cancer (NSCLC) is a heterogeneous disease with an extremely wide range of 5-year survival rates. A composite method of sub-classification for N2 is likely to provide a more accurate method to more finely differentiate prognosis of N2 disease.

METHODS

A total of 720 pN2 (T1-4N2M0) NSCLC cases were enrolled in our retrospective analysis of the proposed composite method. Survival rates were respectively calculated according to the N2 stratification methods: singly by "nodal stations", "nodal zones", or "nodal chains", or by combination of all three. Statistical analysis was carried out by Kaplan-Meier and Cox regression models.

RESULTS

A total of 10,199 lymph nodes (8059 mediastinal; 2140 hilar and intra-lobar) were removed. By nodal station, there were 173 cases of single-station involvement and 547 multi-stations. By nodal zone, there were 413 single-zone involvement and 307 with multiple zones. By nodal chain, there were 311 cases with single-chain and 409 multi-chain involvements. The overall 5-year survival was 20% and median survival time was 27.52 months. The 5-year survival was significantly better for cases of single-zone involvement, as compared to multi-zones (29% vs. 6%, p<0.0001). The 5-year survival rates of single- and multi-chains involvement were 36% and 8%, respectively (p<0.0001). When taking all of the above grouping methods into consideration, the N2 disease state could be further sub-classified into two subgroups with respective survival rates of 36% and 7% (p<0.0001). Subgroup I was composed of individuals with single-chain involvement and having either one or two station metastasis; individuals with any other metastasis combinations formed Subgroup II. Multivariate analysis revealed that the composite sub-classification method, number of positive lymph nodes, ratio of nodal metastasis, and pT information were the most important risk factors of 5-year survival.

CONCLUSIONS

By combining the three N2 stratification methods based on "stations", "zones", and "chains" into one composite method, prognosis prediction was more accurate for N2 NSCLC disease. Single nodal chain involvement, which may be either one or two nodal stations metastasis, is associated with best outcome for pN2 patients.