Role of Pathologic Single-N and Multiple-N Descriptors in Resected Non-Small Cell Lung Cancer

BACKGROUND

The eighth edition of lung cancer N staging assignment includes the location of lymph node metastasis, but does not include single-N and multiple-N descriptors.

RESEARCH QUESTION

Do the single-N and multiple-N statuses stratify the prognosis of patients with non-small cell lung cancer (NSCLC)?

STUDY DESIGN AND METHODS

Using the National Cancer Database, we analyzed patients with pathologically staged N1 and N2 NSCLC. N descriptors were classified into pathological single N1 (pSingle-N1), pathological multiple N1 (pMulti-N1), pathological single N2 (pSingle-N2), and pathological multiple N2 (pMulti-N2). Survival analysis was performed using the Kaplan-Meier method and multivariable Cox regression models.

RESULTS

In the general analysis cohort, 24,531, 22,256, 8,528, and 21,949 patients with NSCLC demonstrated pSingle-N1, pMulti-N1, pSingle-N2, and pMulti-N2 disease, respectively. Patients with pMulti-N1 and pMulti-N2 disease showed a shorter survival than those with pSingle-N1 and pSingle-N2 disease, respectively (hazard ratio [HR], 1.22 [P < .0001] for N1 and 1.39 [P < .0001] for N2). After adjusting age, sex, and histologic findings, the HR for pSingle-N2 compared with pMulti-N1 disease was 1.05 (P = .0031). Patients with pN1 disease were categorized by metastatic lymph node count (1, 2, 3, ≥ 4), showing significant prognostic differences among groups (P < .0001). In the sensitivity analysis cohort (limited to R0 resection, lobectomy, or more; survival ≥ 30 days; ≥ 10 examined lymph nodes; and without neoadjuvant therapy; n = 34,904) and the external validation cohort (n = 708), analyses supported these results.

INTERPRETATION

Patients with NSCLC with one metastatic lymph node, whether in N1 or N2 stations, showed better survival than those with more than one lymph node involved. Patients with NSCLC with a single-skip N2 lymph node metastasis showed survival similar to patients with multiple N1 lymph nodes, and the number of lymph nodes involved in N1 resections up to four or more was sequentially prognostic.

Imaging in Lung Cancer Staging

Lung cancer remains one of the leading causes of mortality worldwide, as well as in the United States. Clinical staging, primarily with imaging, is integral to stratify patients into groups that determine treatment options and predict survival. The eighth edition of the tumor, node, metastasis (TNM-8) staging system proposed in 2016 by the International Association for the Study of Lung Cancer remains the current standard for lung cancer staging. The system is used for all subtypes of lung cancer, including non-small cell lung cancer, small cell lung cancer, and bronchopulmonary carcinoid tumors.

Association of log odds of positive lymph nodes with survival in patients with small cell lung cancer: Results from the SEER database

OBJECTIVES

The prognosis of patients with Small Cell Lung Cancer (SCLC) can be predicted by their Lymph Node (LN) status. The authors aimed to assess the correlations between SCLC survival and number of LN Ratio (LNR), positive LN (pLNs), and Logarithmic Odds of positive LN (LODDS).

METHODS

This cohort study retrospectively included 1,762 patients with SCLC from the SEER database 2004‒2015. The X-tile software was used to determine the cutoff values for pLNs, LNR, and LODDS. The correlations between pLNs, LNR, and LODDS with Overall Survival (OS) and Cancer-Specific Survival (CSS) were explored using Cox regression analysis. The study used the C-index to assess the predictive value of LNR, pLNs, and LODDS on survival.

RESULTS

Among these 1,762 patients, 121 (6.87%) were alive, 1,641 (93.13%) died, and 1,532 (86.95%) died of SCLC. In univariable COX analysis, LNR, pLNs, and LODDS all showed a correlation with CSS and OS (p < 0.05). In multivariable COX analysis, only patients with LODDS (> 0.3 vs. ≤ 0.3) were related to both worse OS (HR = 1.28, 95% CI 1.10‒1.50) and CSS (HR = 1.29, 95% CI 1.10‒1.51), but no correction was observed between LNR and pLNs and survival (p > 0.05). The C-indices for predicting OS for LODDS were 0.552 (95% CI 0.541‒0.563), for LNR 0.504 (95% CI 0.501‒0.507), and for pLNs 0.527 (95% CI 0.514‒0.540). Moreover, the association between LODDS and prognosis in SCLC patients was significant only in patients with LN stage N1 and N2, but not in stage N3.

CONCLUSION

LODDS may be better than other LN assessment tools at predicting survival in SCLC patients.

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.

Survival difference between patients with single versus multiple metastatic lymph nodes and the role of histology in pathological stage II-N1 non-small cell lung cancer

BACKGROUND

Previous studies investigating whether metastatic lymph node count is a relevant prognostic factor in pathological N1 non-small cell lung cancer (NSCLC), showed conflicting results. Hypothesizing that outcome may also be related to histological features, we determined the prognostic impact of single versus multiple metastatic lymph nodes in different histological subtypes for patients with stage II-N1 NSCLC.

METHODS

We performed a retrospective cohort study using data from the Netherlands Cancer Registry, including patients treated with a surgical resection for stage II-N1 NSCLC (TNM 7th edition) in 2010-2016. Overall survival (OS) was assessed for patients with single (pN1a) and multiple (pN1b) metastatic nodes. Using multivariable analysis, we compared OS between pN1a and pN1b in different histological subtypes.

RESULTS

After complete resection of histologically proven stage II-N1 NSCLC, 1309 patients were analyzed, comprising 871 patients with pN1a and 438 with pN1b. The median number of pathologically examined nodes (N1 + N2) was 9 (interquartile range 6-13). Five-year OS was 53% for pN1a versus 51% for pN1b. In multivariable analysis, OS was significantly different between pN1a and pN1b (HR 1.19, 95% CI 1.01-1.40). When stratifying for histology, the prognostic impact of pN1a/b was only observed in adenocarcinoma patients (HR 1.44, 95% CI 1.15-1.81).

CONCLUSION

Among patients with stage II-N1 adenocarcinoma, the presence of multiple metastatic nodes had a significant impact on survival, which was not observed for other histological subtypes. If further refinement as to lymph node count will be considered for incorporation into a new staging system, evaluation of the role of histology is recommended.

The number of metastatic lymph nodes is more predictive of prognosis than location-based N stage for nonsmall cell lung cancer: a retrospective cohort study

BACKGROUND

The eighth edition of nodal classification is defined only by the anatomical location of metastatic lymph nodes and has limited prognostic discrimination power. The authors aimed to evaluate the prognostic significance and discriminatory capability of the number of metastatic lymph nodes (nN) in resected nonsmall cell lung cancer.

MATERIALS AND METHODS

Patients with stage IA to IIIB resected nonsmall cell lung cancer between 1 January 2009 and 31 December 2013 were analyzed as a Chinese cohort. The optimal thresholds for the nN classification were determined by the X-tile. The receiver operating characteristic curve, net reclassification improvement and standardized net benefit calculated by decision curve analysis was estimated to quantify the nN classification's performance in prognostic stratification. External validation in the surveillance, epidemiology, and end results database was performed to test the robustness of the nN classification.

RESULTS

Both cohorts showed a stepwise prognosis deterioration with increasing nN. One to three, four to six, and more than six were selected as optimal thresholds of nN classification in the Chinese cohort, which included 4432 patients, then validated in the SEER cohort ( n =28 022 patients). Multivariate Cox analysis showed the nN classification was an independent predictive factor for overall survival in both cohorts (Chinese cohort and SEER cohort: N 0 vs. N 1-3 , P <0.001; N 0 vs. N 3-6 , P <0.001; N 0 vs. N >6 , P <0.001). And prognostic discriminatory capability was improved in the nN classification compared with location-based N classification [5-year NRI score, 0.106 (95% CI: 0.049-0.132) and 5-year time-independent AUC, 0.593 (95% CI: 0.560-0.625) vs. 0.554 (95% CI: 0.520-0.588), P <0.001].

CONCLUSIONS

The nN classification tended to be a superior prognostic indicator than the location-based N classification. The number of metastatic lymph nodes should be considered in the future revision of the TNM system.

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.

Radiologic Extranodal Extension of Metastatic Lymph Nodes in Patients With Non-Small Cell Lung Cancer: Prognostic Utility and Diagnostic Performance

BACKGROUND. Pathologic extranodal extension (ENE) in metastatic lymph nodes (LNs) has been associated with unfavorable prognosis in patients with non-small cell lung cancer (NSCLC). OBJECTIVE. The purpose of this article was to evaluate the prognostic utility of radiologic ENE and its diagnostic performance in predicting pathologic ENE in patients with NSCLC. METHODS. This retrospective study included 382 patients (mean age, 67 ± 10 [SD] years; 297 men, 85 women) diagnosed with NSCLC and clinical N1 or N2 disease between January 2010 and December 2016. Two thoracic radiologists reviewed staging chest CT examinations to record subjective overall impression for radiologic ENE (no ENE, possible/probable ENE, or unambiguous ENE), reviewing 30 examinations in consensus and the remaining examinations independently. Kaplan-Meier survival analysis and multivariable Cox proportional hazards model were used to evaluate the utility of radiologic ENE in predicting overall survival (OS). Prognostic utility of radiologic ENE was also assessed in patients with clinical N2a disease. In patients who underwent surgery, sensitivity and specificity were determined of radiologic unambiguous ENE in predicting pathologic ENE. RESULTS. The 5-year OS rates for no ENE, possible/probable ENE, and unambiguous ENE were 44.4%, 39.1%, and 20.9% for reader 1 and 45.7%, 36.6%, and 25.6% for reader 2, respectively. Unambiguous ENE was an independent prognostic factor for worse OS (reader 1: adjusted HR, 1.72, p = .008; reader 2: adjusted HR, 1.56, p = .03), whereas possible/probable ENE was not (reader 1: adjusted HR, 1.18, p = .33; reader 2: adjusted HR, 1.21, p = .25). In patients with clinical N2a disease, 5-year OS rate in patients with versus without unambiguous ENE for reader 1 was 22.2% versus 40.6% (p = .59) and for reader 2 was 27.6% versus 41.0% (p = .49). In 203 patients who underwent surgery (66 with pathologic ENE), sensitivity and specificity of radiologic unambiguous ENE for predicting pathologic ENE were 11% and 93% for reader 1 and 23% and 87% for reader 2. CONCLUSION. Radiologic unambiguous ENE was an independent predictor of worse OS in patients with NSCLC. The finding had low sensitivity but high specificity for pathologic ENE. CLINICAL IMPACT. Radiologic ENE may have a role in NSCLC staging workup and treatment selection.

Occult lymph node metastasis is not a favorable factor for resected NSCLC patients

BACKGROUND

This study was to compare the clinical presentations and survivals between the non-small cell lung cancer (NSCLC) patients with occult lymph node metastasis (OLNM) and those with evident lymph node metastasis (ELNM). We also intended to analyze the predictive factors for OLNM.

METHODS

Kaplan-Meier method with log-rank test was used to compare survivals between groups. Propensity score matching (PSM) was used to reduce bias. The least absolute shrinkage and selection operator (LASSO)-penalized Cox multivariable analysis was used to identify the prognostic factors. Random forest was used to determine the predictive factors for OLNM.

RESULTS

A total of 2,067 eligible cases (N0: 1,497 cases; occult N1: 165 cases; evident N1: 54 cases; occult N2: 243 cases; evident N2: 108 cases) were included. The rate of OLNM was 21.4%. Patients with OLNM were tend to be female, non-smoker, adenocarcinoma and had smaller-sized tumors when compared with the patients with ELNM. Survival curves showed that the survivals of the patients with OLNM were similar to those of the patients with ELNM both before and after PSM. Multivariable Cox analysis suggested that positive lymph nodes (PLN) was the only prognostic factor for the patients with OLNM. Random forest showed that clinical tumor size was an important predictive factor for OLNM.

CONCLUSIONS

OLNM was not rare. OLNM was not a favorable sign for resected NSCLC patients with lymph node metastasis. PLN determined the survivals of the patients with OLNM. Clinical tumor size was a strong predictive factor for OLNM.

True Prevalence of Unforeseen N2 Disease in NSCLC: A Systematic Review + Meta-Analysis

Patients with unforeseen N2 (uN2) disease are traditionally considered to have an unfavorable prognosis. As preoperative and intraoperative mediastinal staging improved over time, the prevalence of uN2 changed. In this review, the current evidence on uN2 disease and its prevalence will be evaluated. A systematic literature search was performed to identify all studies or completed, published trials that included uN2 disease until 6 April 2023, without language restrictions. The Newcastle-Ottawa Scale (NOS) was used to score the included papers. A total of 512 articles were initially identified, of which a total of 22 studies met the predefined inclusion criteria. Despite adequate mediastinal staging, the pooled prevalence of true unforeseen pN2 (9387 patients) was 7.97% (95% CI 6.67-9.27%), with a pooled OS after five years (892 patients) of 44% (95% CI 31-58%). Substantial heterogeneity regarding the characteristics of uN2 disease limited our meta-analysis considerably. However, it seems patients with uN2 disease represent a subcategory with a similar prognosis to stage IIb if complete surgical resection can be achieved, and the contribution of adjuvant therapy is to be further explored.

Surgical Treatment Outcomes of Patients with Non-Small Cell Lung Cancer and Lymph Node Metastases

This study aimed to investigate the appropriate subgroups for surgery and adjuvant chemotherapy in patients with non-small-cell lung cancer (NSCLC) and nodal metastases. We retrospectively reviewed 210 patients with NSCLC and nodal metastases who underwent surgery and examined the risk factors for poor overall survival (OS) and recurrence-free probability (RFP) using multivariate Cox proportional hazards analysis. Pathological N1 and N2 were observed in 114 (52.4%) and 96 (47.6%) patients, respectively. A single positive node was identified in 102 patients (48.6%), and multiple nodes were identified in 108 (51.4%). Multivariate analysis revealed that vital capacity < 80% (hazard ratio [HR]: 2.678, 95% confidence interval [CI]: 1.483-4.837), radiological usual interstitial pneumonia pattern (HR: 2.321, 95% CI: 1.506-3.576), tumor size > 4.0 cm (HR: 1.534, 95% CI: 1.035-2.133), and multiple-node metastases (HR: 2.283, 95% CI: 1.517-3.955) were significant independent risk factors for poor OS. Tumor size > 4.0 cm (HR: 1.780, 95% CI: 1.237-2.562), lymphatic permeation (HR: 1.525, 95% CI: 1.053-2.207), and multiple lymph node metastases (HR: 2.858, 95% CI: 1.933-4.226) were significant independent risk factors for recurrence. In patients with squamous cell carcinoma (n = 93), there were no significant differences in OS or RFP between those who received platinum-based adjuvant chemotherapy (n = 25) and those who did not (n = 68), at p = 0.690 and p = 0.292, respectively. Multiple-node metastases were independent predictors of poor OS and recurrence. Patients with NSCLC and single-node metastases should be considered for surgery despite N2 disease. Additional treatment with platinum-based adjuvant chemotherapy may be expected, especially in patients with squamous cell carcinoma.

Lymph Node Log-Odds Ratio Accurately Defines Prognosis in Resectable Non-Small Cell Lung Cancer

Objectives: The ratio of positive and resected lymph nodes (LN ratio) has been shown to be prognostic in non-small cell lung cancer (NSCLC). Contrary to the LN ratio, calculating the LN log-odds ratio (LN-LOR) additionally considers the total number of resected lymph nodes. We aim to evaluate LN-LOR between positive and resected lymph nodes as a prognostic factor in operable NSCLC. Methods: Patients with NSCLC who underwent curative intent lobectomy treated at two high-volume centers were retrospectively studied. LN-LOR was dichotomized according to impact on OS and further combined with N descriptors and correlated with clinical variables and survival. Results: 944 patients were included. Cut-off analysis revealed that an LN-LOR of −0.34 significantly discriminated patients according to OS (p < 0.001, chi-squared test 41.26). When combined with N1 and N2 descriptors, LN-LOR low risk (median OS not reached and 83 months) and LN-LOR high-risk patients (median OS 50 and 59 months) had similar survival irrespective of the anatomical location of the positive lymph nodes. Multivariable Cox regression analysis revealed that age (HR 1.02, 95% CI 1.001–1.032), sex (male, HR 1.65, 95% CI 1.25–2.19), histological subtype (HR 2.11, 95% CI 1.35–3.29), pathological stage (HR 1.23, 95% CI 1.01–1.45) and LN-LOR risk groups (low risk, HR 0.48, 95% CI 0.32–0.72) were independent prognostic factors for OS. Conclusions: This retrospective two-center analysis shows that LN-LOR is significantly associated with OS in resectable NSCLC and might better reflect the biological behavior of the disease, regardless of anatomical lymph node locations. This finding may additionally support the value of extensive LN dissection.

The effect of lymph node ratio on survival in non-small-cell lung cancer

BACKGROUND

The aim of this study was to evaluate the effect of prognostic factors and lymph node ratio (LNR) on survival in patients with resected non-small-cell lung cancer (NSCLC).

METHODS

Data from 421 patients with NSCLC who underwent complete resection between 2009 and 2015 were evaluated retrospectively. LNR was defined as the ratio of positive lymph nodes to the total number of lymph nodes removed. Associations between overall survival (OS) and LNR, node (N) status, and histopathologic status were evaluated.

RESULTS

The 5-year survival rate was 42.5% among all patients and 26.6% for patients aged 65 years or older. In the multivariate analysis, age ≥65 years, advanced-stage disease, non-squamous cell carcinomas, pN status, and having multiple-station pN2 and multiple-station pN1 disease were found to be poor prognostic factors (p < 0.05). There was no statistical difference in survival between patients with LNR (hazard ratio: 1.04, p = 0.45).

CONCLUSION

The results of our study indicate that pN stage, histopathologic type, pT stage, and geriatric age were the most important poor prognostic factors associated with survival after NSCLC resection. Although LNR is a factor associated with survival in gastrointestinal cancers, it did not impact survival in our study.

Imaging of Lung Cancer Staging

Lung cancer is a leading cause of cancer-related mortality worldwide. Imaging is integral in accurate clinical staging to stratify patients into groups to predict survival and determine treatment. The eighth edition of the tumor, node, and metastasis (TNM-8) staging system proposed by the International Association for the Study of Lung Cancer in 2016, accepted by both the Union for International Cancer Control and the American Joint Committee on Cancer, is the current standard method of staging lung cancer. This single TNM staging is used for all histologic subtypes of lung cancer, including nonsmall cell lung cancer, small cell lung cancer, and bronchopulmonary carcinoid tumor, and it addresses both clinical and pathologic staging. Familiarity with the strengths and limitations of imaging modalities used in staging, the nuances of TNM-8, its correct nomenclature, and potential pitfalls are important to optimize patient care. In this article, we discuss the role of computed tomography (CT) and positron emission tomography/CT in lung cancer staging, as well as current imaging recommendations pertaining to TNM-8.

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.

Lymph node ratio predicts overall survival in patients with stage II non-small cell lung cancer: a population-based SEER analysis

BACKGROUND

In non-small-cell lung cancer (NSCLC), there are many factors that affect prognosis, and the lymph node ratio (LNR) may play a significant role. Our study aimed to confirm the value of the LNR in the prognosis of patients with stage II NSCLC.

METHODS

Patient data were obtained from the Surveillance, Epidemiology and End Results (SEER) database. The classification for the LNR was best determined using the X-tile method. The correlation between the LNR and overall survival (OS) was validated after the Kaplan-Meier analysis was performed. To determine the correlation between the LNR and survival, stratification and the Cox regression analysis were used.

RESULTS

In our study, 14,183 stage II NSCLC patients were included. Among them, 8303 patients had N1 disease. According to the X-tile analysis, the optimal critical points for the LNR in N1 patients with NSCLC was 0.21 and 0.38. We categorized the cohorts as low (LNR-L ≤ 0.21; n = 5158, 62.1%), medium (0.21 < LNR-M ≤ 0.38; n = 1736, 20.9%), and high (LNR-H > 0.38; n = 1409, 17.0%). According to the Kaplan-Meier analysis, the patients with a high LNR were considerably worse than those with a medium or low LNR (P < 0.001), which was also proven by stratified and multivariate analyses. The value of the LNR was reflected in all the subgroup analyses, especially in patients ages < 60 years. The multivariate competing risks regression analysis revealed that younger age, female sex, T1 disease, adenocarcinoma and N0 disease was associated with a better prognosis after controlling for potential confounders (P < 0.001).

CONCLUSIONS

For patients with stage II NSCLC, the LNR is valuable for assessing prognosis. A higher LNR indicates a worse prognosis.

The impacts of isolated N1 lymph nodes metastasis on prognosis in non-small cell lung cancer: A single-center experience

Background: This study aims to investigate long-term results related to N1 group metastases with respect to anatomical localization and many external parameters and to examine the effect of these parameters on prognosis in patients with in nonsmall cell lung cancer.

Methods: Between January 2006 and May 2019, a total of 52 patients (44 males, 8 females; mean age: 59.9±9.5 years; range, 42 to 80 years) who underwent lobectomy due to primary lung malignancy were retrospectively analyzed. The N1 lymph nodes were divided into three anatomical groups as hilar, peribronchial, and intraparenchymal. Demographic features, tumor features, follow-up characteristics, and survival and diseasefree survival parameters were analyzed for each group. The results were also examined in terms of number of metastasis, number of metastatic levels, rate of metastasis, and histopathological type.

Results: The five-year survival rate was 66.4% in the peribronchial group and 50% in the hilar group. The five-year disease-free survival rate was 45.7% in the peribronchial group and 37.5% in the hilar group. There was no statistically significant difference between the groups in terms of survival and disease-free survival for anatomical localization, number of metastasis, number of metastatic levels, rate of metastasis, and histopathological type (p>0.05 for all).

Conclusion: The structure that would be formed by examining N1 in terms of parameters such as subtitle levels, number of metastasis, number of metastatic stations, rate of metastasis or combinations of these would have a more impact on the decisions in the follow-up and treatment process in this patient population.

Long-Term Survival According to N Stage Diagnosed by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration in Non-Small Cell Lung Cancer

BACKGROUND

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is the main procedure for mediastinal staging. However, long-term survival analyses according to cN stage diagnosed by EBUS-TBNA (abbreviated to eN stage) have not been reported. The value of EBUS-TBNA has not been assessed through an analysis of survival in false-negative EBUS-TBNA cases.

RESEARCH QUESTIONS

What is the prognostic impact of eN stage in non-small cell lung cancer (NSCLC)? What is the survival rate in false-negative EBUS-TBNA cases?

STUDY DESIGN AND METHODS

We retrospectively (January 2006-December 2011) reviewed the medical records of NSCLC patients who underwent EBUS-TBNA (± transesophageal approach) for initial staging (n=1,089). Mediastinoscopy was not performed for EBUS-TBNA negative cases. We performed 5-year survival analyses according to eN stage and treatment modality. Survival in false-negative EBUS cases was compared with that in pN0-1 patients, including 941 non-EBUS cases, during the same period.

RESULTS

Among 1,089 EBUS patients (eN0-1=681, eN2=314, eN3=94), we observed significant differences in survival between the eN stages [eN0-1 vs eN2; p <0.0001, eN2 vs eN3; p=0.0118, estimated 5-year overall survival (5YOS) rate: eN0-1=57.4%, eN2=23.2%, eN3=12.8%]. Surgery cases had better survival than non-surgery cases among eN0-1 and eN2 patients (eN0-1/surgery vs. eN0-1/no surgery; p<0.0001, eN2/surgery vs. eN2/no surgery; p<0.0001). Among eN0-1 patients, there were 55 false-negative cases (eN0-1/pN2-3, pN2=54, pN3=1). The 5YOS rates of pN0, pN1, and eN0-1/pN2-3 patients were 76.4%, 56.0% and 56.4%, respectively. eN0-1/pN2-3 patients had worse survival than pN0 patients (p=0.0061), whereas there was no significant difference compared with pN1 patients (p=0.9191).

INTERPRETATIONS

Long-term survival significantly differed according to eN stage in NSCLC, highlighting the importance of EBUS-TBNA in NSCLC staging. False-negative EBUS-TBNA cases had favorable survival which was similar to that of pN1 patients, which may provide a rationale for performing surgery after negative EBUS-TBNA results.

Prognostic nomogram for predicting long-term survival in bronchopulmonary carcinoid tumor patients receiving resection

Background

We analyzed bronchopulmonary carcinoid tumor (BPC) patients receiving resection from the Surveillance, Epidemiology, and End Results (SEER) database to identify the predictive factors of their survival. Then, we developed and validated nomograms to predict overall survival (OS) and cancer-specific survival (CSS) in BPC patients.

Methods

BPC patients registered in the SEER database were included. They were divided into a training set and an internal validation set (7:3). BPC patients from our center were included as an external validation set. Independent prognostic factors identified by a Cox regression model in the training set were used to construct nomograms to predict survival. Discrimination and calibration plots were used to evaluate the predictive accuracy of the nomograms. The nomograms were evaluated in both the internal and the external validation datasets.

Results

Age, pathological type, and N stage were identified as independent prognostic factors of OS and CSS by Cox analyses (all P<0.05). Tumor size ≥2.5 cm (P=0.045) was an independent factor for unfavorable CSS. Based on these variables, nomograms were constructed. All concordance indexes of the training set, internal validation set, and external validation set indicated that the nomograms had the preferable discriminatory ability. The calibration plots for predictions of the 1-, 3-, and 5-year OS and CSS were in excellent agreement.

Conclusions

Age, pathological type, N stage, and tumor size were independent predictive factors of prognosis in BPC patients receiving resection. These nomograms could serve as effective and accurate tools for the prognostic evaluation of patients with BPCs.

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.

External validation of the N descriptor in the proposed tumour-node-metastasis subclassification for lung cancer: the crucial role of histological type, number of resected nodes and adjuvant therapy

OBJECTIVES

Overlapping survival curves for N1b (multiple N1 stations), N2a2 (single N2 station + N1 involvement) and N2a1 (skip N2 metastasis) limit the current tumour-node-metastasis (TNM) node (N) subclassification for node involvement. We validated externally the proposed subclassification.

METHODS

Clinical records from a multicentric database comprising 1036 patients with pulmonary adenocarcinoma (ADC) or squamous cell carcinoma with N1/N2 involvement who underwent, from January 2002 to December 2014, complete lung resections were retrospectively reviewed. Patients were categorized according to the 8th TNM N subclassification proposal. Histological type, number of resected nodes (#RN) and adjuvant therapy (ADJ) were considered limiting factors.

RESULTS

No difference in the 5-year overall survival (-OS) was noted between N1b and N2a1 (49.6% vs 44.8%, P = 0.72); instead, the 5-year-OS was significantly improved in patients with squamous cell carcinoma (63% in N1b vs 30.7% in N2a1, P = 0.04). In patients with ADC, the 5-year-OS was better in those with N2a1 than with N1b (50.6% vs 37.5%, P = 0.09). When we compared N1b with N2a2, the 5-year-OS was statistically significant (49.6% vs 32.8%, P = 0.02); considering only patients with squamous cell carcinoma (63% vs 25.8%, P = 0.003), #RN >10 (63.2% vs 35.3%, P = 0.05) and without ADJ (56.4% vs 24.5%, P = 0.02), the 5-year-OS was significantly different. Differences were not significant for ADC, #RN <10 and ADJ. Finally, the 5-year-OS was statistically significant when we compared N2a1 with N2a2 of the total cohort (44.8% vs 32.8%, P = 0.04), in ADC (5-year-OS 50.6% vs 36.5%, P = 0.04) and #RN >10 (5-year-OS 49.8% vs 32.1%, P = 0.03) without ADJ.

CONCLUSIONS

Histological type, ADJ and #RN are relevant prognostic factors in N + non-small-cell lung cancer. Considering these results, we may better interpret the prognosis prediction limits of the proposed 8th TNM subclassification for the N descriptor.

Application of N Descriptors Proposed by the International Association for the Study of Lung Cancer in Clinical Staging

Background Patients with N1 or N2 non-small cell lung cancer exhibit prognostic heterogeneity. To refine the current N staging system, new N stages were proposed by the International Association for the Study of Lung Cancer. However, those proposed new N stages have not been validated. Purpose To evaluate the prognostic performance of the proposed N descriptors for clinical staging. Materials and Methods Participants with non-small cell lung cancer without distant metastasis from January 2010 to December 2014 were retrospectively included. Each patient's clinical N (cN) stage was assigned to one of seven categories (cN0, cN1a, cN1b, cN2a1, cN2a2, cN2b, cN3). The 5-year overall survival rates were estimated with the Kaplan-Meier method. The adjusted hazard ratios (HRs) and their 95% CIs were estimated by using a multivariable Cox proportional hazard model. Ad hoc analyses according to lymph node (LN) size were performed. Results A total of 1271 patients (median age, 66 years; interquartile range, 59-73 years; 812 men) were included. The 5-year overall survival rates were 77.3%, 53.7%, 36.0%, 29.2%, 34.4%, 18.0%, and 12.4% for stages cN0, cN1a, cN1b, cN2a1, cN2a2, cN2b, and cN3, respectively. Patients with cN2b disease had a worse prognosis than patients with cN2a disease (HR, 1.53; 95% CI: 1.06, 2.22; P = .02). There was no prognostic difference between cN1b and cN1a (HR, 1.13; 95% CI: 0.61, 2.09; P = .71); however, there was a difference between cN1 subgroups when stratified by LN size (≥2 cm; HR, 2.26; 95% CI: 1.16, 4.44; P = .02). Within cN2a disease, there were no differences between cN2a1 and cN2a2 (HR, 0.98; 95% CI: 0.61, 1.56; P = .93) or between subgroups according to LN size (HR, 0.74; 95% CI: 0.40, 1.37; P = .34). Conclusion A survival difference was observed between single- and multistation involvement among cN2 disease. The number of involved lymph node stations in patients with cN1 disease and the presence of skip metastasis in patients with cN2 disease were not associated with survival differences. © RSNA, 2021 Online supplemental material is available for this article.

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.

Surgical Outcomes of Non-Small Cell Lung Cancer in Single-Zone N2 in the Aortopulmonary Zone

OBJECTIVES

 We evaluate the surgical outcome of clinically single-zone N2 lung cancer limited to aortopulmonary zone (AP zone; lymph node #5 or #6).

PATIENTS AND METHODS

 We performed a retrospective analysis of patients with non-small cell lung cancer, in whom mediastinal lymph node metastasis was confined to AP zone.

RESULTS

 A total of 84 patients who underwent upfront surgery were included in final analysis. Among these patients, pathological nodal outcomes were pN0-1 in 27 patients (32.1%), pN2a in 31 (36.9%), and pN2b in 26 (31.0%). In multivariate analysis, adenocarcinoma (p = 0.005) and staging workup without endobronchial ultrasound-transbronchial needle aspiration (p = 0.002) were independent risk factors for unexpected pN2b. The 5-year overall survival (OS) and disease-free survival (DFS) were 55.9 and 54.4%, respectively. There was no survival difference among patients with pN0-1, pN2a, and pN2b (p = 0.717). In survival analysis, there were no significant risk factors for OS. However, female sex and the ratio of positive lymph nodes to removed lymph nodes were significant risk factors for DFS in multivariate analysis (p = 0.032 and p = 0.009).

CONCLUSION

 In this study, cN2a in the AP zone with current diagnostic tool exhibited a relatively high false-positive rate (cN2/pN0-1; 32.1%). However, despite the possibility of pN2b, there were no significant differences in survival outcome according to the pathologic nodal stage.

Survival Analysis in Single N2 Station Lung Adenocarcinoma: The Prognostic Role of Involved Lymph Nodes and Adjuvant Therapy

BACKGROUND

Prognostic factors in patients with single mediastinal station (sN2) involvement continues to be a debated issue.

METHODS

Data on 213 adenocarcinoma patients with sN2 involvement and who had undergone complete anatomical lung resection and lymphadenectomy, were retrospectively reviewed. Clinical and pathological characteristics together with adjuvant therapy (AD) and node (N) status classifications (number of resected nodes (#RN), number of metastatic nodes (#MN), and node ratio (#MN/#RN = NR) were analyzed.

RESULTS

Univariable analysis confirmed that age (0.009), #MN (0.009), NR (0.003), #N1 involved stations (p = 0.003), and skip metastases (p = 0.005) were related to overall survival (OS). Multivariable analysis confirmed, as independent prognostic factors, age <66 years and NR with a three-year OS (3YOS) of 78.7% in NR < 10% vs. 46.6% in NR > 10%. In skip metastases, NR (HR 2.734, 95% CI 1.417-5.277, p = 0.003) and pT stage (HR2.136, 95% CI 1.001-4.557, p = 0.050) were confirmed as independent prognostic factors. AD did not influence the OS of patients with singular positive lymph nodes (p = 0.41), while in patients with multiple lymph nodes and AD, a significantly better 3YOS was demonstrated, i.e., 49.1% vs. 30% (p = 0.004). In patients with N2 + N1 involvement, age (p = 0.002) and AD (p = 0.022) were favorable prognostic factors.

CONCLUSIONS

Adenocarcinoma patients with single N2 station involvement had a favorable outcome in the case of skip metastases and low NR. Adjuvant therapy improves survival with multiple nodal involvement, while its role in single node involvement should be clarified.

Is Adjuvant Radiochemotherapy Always Mandatory in Patients with Resected N2 Non-Small Cell Lung Cancer?

BACKGROUND

 In patients with non-small cell lung cancer (NSCLC), the pathologic union for international cancer control (UICC) stage IIIA is a heterogeneous entity, with different forms of N2-lymph node involvement representing different prognoses. Although a multimodality treatment approach, including surgery, systemic therapy, and/or radiotherapy, is almost always recommended, in this retrospective observational study, we sought to determine whether long-term survival might be possible in selected patients who are treated with complete surgical resection alone.

METHODS

 Between 2013 and 2018, we retrospectively identified 24 patients with NSCLC (16 men and 8 women), who were found to have pathologic N2-lymph node involvement, and were treated with complete surgical lung resection and systematic mediastinal and hilar lymph node dissection but no neoadjuvant or adjuvant treatment.

RESULTS

 The most frequent reason (n = 14) for forgoing adjuvant treatment was patient refusal. The mean overall survival (OS) was 34.5 months (interquartile range [IQR]: 15.5-53.5 months). The mean disease-free survival (DFS) was 18 months (IQR: 4.75-46.75 months). We identified five patients who survived at least 5 years without recurrence (21%). In each of these cases, the nodal metastases were restricted to a single level and no extracapsular lymph node involvement were detected. Additionally, worse DFS was associated with pT3/4 (vs. a lower T-stage), as well as microscopic lymphovascular invasion.

CONCLUSION

 Although the small sample size precludes any definitive conclusions, it was possible to demonstrate that long-term survival without neoadjuvant and adjuvant treatment is possible in some patients if complete tumor and nodal resection is performed.

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.

Incorporating the Number of PLN into the AJCC Stage Could Better Predict the Survival for Patients with NSCLC: A Large Population-Based Study

Purpose

This study aimed to investigate the application of the number of positive lymph nodes (PLNs) in tumor, node, metastasis (TNM) staging system of non-small cell lung cancer (NSCLC) patients. Patients and Methods. We screened a total of 15820 patients with resected NSCLC between 2004 and 2015 from SEER database. The X-tile model was used to determine the cutoff values of the number of PLNs. Overall survival (OS) curves were plotted using the Kaplan–Meier method, and the differences among the individual groups were defined using the log-rank test. Cox regression model was used to perform univariate and multivariate analyses and to assess the association between the number of PLNs and OS.

Results

In this study, using the X-tile model, we screened three different cutoff values, including nN0, nN1–3, and nN4-. Survival curves demonstrated that our defined nN stage had a significant predictive value for OS (P < 0.001). In the univariate and multivariate Cox analyses, the result showed that nN stage was a significant prognostic factor of OS for NSCLC patients (P < 0.001). Subsequently, we classified the patients into five subgroups based on the combination of pN and nN stages, including pN0 + nN0, pN1 + nN1-3, pN2 + nN1-3, pN1 + nN4-, and pN2 + nN4-. Moreover, survival curves revealed significant differences among these five groups (P < 0.001).

Conclusion

A combination of pathological LNs (pN) and the number of LN (nN) involvement in NSCLC patients had a better prognostic value than the current TNM staging system based on only pN stage.

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.

Combining node location and node ratio as a prognostic factor for surgical resected non-small cell lung cancer: a population-based study

Background

In the TNM system only the anatomic location is used to define nodal status. In this study we aim to evaluate the effectiveness of combining the location and ratio of metastatic lymph node (pN-NR) for the prognosis of non-small cell lung cancer (NSCLC).

Methods

Patients with pN1/pN2 NSCLC were retrieved from the SEER database. The optimal cut point of NR was determined with the maximal selecting test. All patients were divided into 4 categories with combination of pN (pN1 or pN2) and NR (low or high). The pN-NR was investigated as a predictor of overall survival (OS) and cause-specific survival (CSS) using Cox regression models. Survival curves were plotted using the Kaplan-Meier method and the difference was compared with log-rank test.

Results

A total of 12,170 patients were enrolled. The optimal cut point of NR was 0.3. Patients were divided into 4 groups: pN1-NR <0.3, pN1-NR ≥0.3, pN2-NR <0.3 and pN2-NR ≥0.3. The pN-NR was an independent prognostic factor for survival. Compared with pN1-NR <0.3, the hazard ratio of OS was 1.405 (95% CI: 1.295-1.524), 1.183 (95% CI: 1.113-1257) and 1.717 (95% CI: 1.607-1.835) times higher for pN1-NR ≥0.3, pN2-NR <0.3 and pN2-NR ≥0.3 group, respectively. The survival curves of OS separated well between the 4 pN-NR groups, with 5-year OS 47.1% for pN1-NR <0.3, 43.0% for pN2-NR <0.3, 35.0% for pN1-NR ≥0.3 and 28.5% for pN2-NR ≥0.3, and the P value between neighboring curves was statistically significantly. The same trend was observed for CSS. Subgroup analysis revealed similar results except the pneumonectomy group.

Conclusions

pN-NR could be a good predictor for the prognosis of NSCLC.

Prognostic value of log odds of positive lymph nodes in node-positive lung squamous cell carcinoma patients after surgery: a SEER population-based study

Background

Log odds of positive lymph nodes (LODDS) is a novel and promising ratio-based lymph node (LN) staging system in many malignancies. This study aimed to evaluate the prognostic value of LODDS, and comprehensively compare the prognostic predictive performance of LODDS with the American Joint Committee on Cancer (AJCC) N classification, number of positive lymph node (NPLN), and lymph node ratio (LNR) among node-positive lung squamous cell carcinoma (SCC) patients after surgery.

Methods

We identified 2,561 patients with N1/N2 stage SCC diagnosed between 2004 and 2014 from the Surveillance, Epidemiology, and End Results (SEER) database. X-tile analysis was used to calculate the optimal cut-off value for each staging system. Univariable and Multivariable Cox regression analyses were used to assess the association of cancer-specific survival (CSS), and overall survival (OS) with N, NPLN, LNR, and LODDS, separately, and integrally. Moreover, linear trend χ² score, likelihood ratio (LR) test, Akaike information criterion (AIC), and Harrell concordance index (C-index) were adopted as criteria for assessing the predictive ability of each model.

Results

The optimal cut-off values for NPLN, LNR, and LODDS were 3, 0.28, and −0.37, respectively. N, NPLN, LNR, and LODDS were identified as independent prognostic predictors for CSS and OS in patients with SCC when each of them was incorporated into multivariable Cox model separately. Additionally, LODDS had the higher linear trend χ² score, higher LR χ² test score, lower AIC, and higher C-index compared to the other three systems. Moreover, a combination of N, NPLN, and LODDS was superior to any staging system alone for predicting prognosis.

Conclusions

LODDS showed better predictive performance than N, NPLN, and LNR among patients with node-positive SCC after surgery. A combination of LODDS and the current AJCC TNM classification has the potential for becoming a better staging method to more precisely predicting prognosis.

Preoperative staging of the mediastinum is an essential and multidisciplinary task

Mediastinal staging is a crucial step in the management of patients with NSCLC. With the recent development of novel techniques, mediastinal staging has evolved from an activity of interest mainly for thoracic surgeons to a joint effort carried out by many specialists. In this regard, the debate of cases in MDT sessions is crucial for optimal management of patients. Current evidence-based clinical guidelines for preoperative NSCLC staging recommend that mediastinal staging should be performed with increasing invasiveness. Image-based techniques are the first approach, although they have limited accuracy and findings must be confirmed by pathology in almost all cases. In this setting, the advent of radiomics is promising. Invasive staging depends on procedural factors rather than diagnostic performance. The choice between endoscopy-based or surgical procedures should depend on the local expertise of each centre. As the extension of mediastinal disease in terms of number of involved lymph nodes and nodal stations affects prognosis and the choice of treatment, systematic samplings are preferred over random targeted samplings. Following this approach, a diagnosis of single mediastinal nodal involvement can be unreliable if all reachable mediastinal nodal stations have not been assessed. The performance of confirmatory mediastinoscopy after a negative endoscopy-based procedure is controversial but currently recommended. Current indications of invasive staging in patients with radiologically normal mediastinum have to be re-evaluated, especially for central tumour location.

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.

The prognostic significance of the 8th edition AJCC TNM staging system for non-small-cell lung cancer is not applicable to lung cancer as a second primary malignancy

BACKGROUND AND OBJECTIVES

It is unclear whether the prognostic significance of the 8th American Joint Committee on Cancer (AJCC) tumor, node, metastasis (TNM) staging system for non-small-cell lung cancer (NSCLC) is applicable to lung cancer as a second primary malignancy (LCSPM). This study used a population-based database to evaluate this relationship.

METHODS

Patients diagnosed with second primary lung cancer after a nonpulmonary malignancy were identified from the Surveillance, Epidemiology and End Results (SEER) registry from 2004 to 2015. Cumulative incidence function (CIF) and multivariable CIF regression analyses were performed to estimate the difference in disease-specific mortality (DSM) among different TNM stages.

RESULTS

Our cohort included 2687 patients from the SEER database. After CIF analysis, although rates of 1-year, 3-year, and 5-year DSM trended higher with increasing TNM stages, the DSM curves overlapped for many subcategories. In a multivariable regression analysis, hazards ratios (HRs) for subcategories of stage Ι demonstrated no significant difference compared with the reference stage ΙA1 ([ΙA2 HR = 1.120; 95% confidence interval [CI], 0.477-2.626]; [ΙA3 HR = 1.762; 95% CI, 0.752-4.126]; [ΙB HR = 2.003; 95% CI, 0.804-4.911]). The following HRs trended higher for increasing TNM stages but with overlapping CIs among adjacent stage groupings.

CONCLUSION

The 8th edition AJCC TNM staging system fails to provide accurate prognostic value for LCSPM.

Skip N2 Metastasis in Pulmonary Adenocarcinoma: Good Prognosis Similar to N1 Disease

INTRODUCTION

The prognostic effect and mechanism of skip N2 lung cancer remain unclear. Our study aimed to elucidate the influence of skip N2 on overall survival (OS) and disease-free survival (DFS) compared with N1 and non-skip N2 in patients with lung adenocarcinoma.

PATIENTS AND METHODS

Patients with lung adenocarcinoma and lymph node involvement between May 2011 and December 2015 were retrospectively analyzed. The outcomes of skip N2 patients were compared with N1 and non-skip N2 patients. Prognosis was further investigated according to the N status in different adenocarcinoma subtypes. Univariate and multivariate analyses were carried out to define independent risk factors for OS and DFS.

RESULTS

A total of 456 patients with lung adenocarcinoma, 169 with N1 disease, 81 with skip N2 disease, and 206 with non-skip N2 disease, were enrolled in this study. All tumors were invasive adenocarcinoma, and the predominant subtypes were acinar in 252, papillary in 42, solid in 119, micropapillary in 20, and invasive mucinous adenocarcinoma in 23 patients. The DFS and OS of N1 and skip N2 diseases were similar and significantly better than those of patients with non-skip N2 disease. The prognosis according to lymph node status was significantly different in acinar-predominant subtypes in terms of both OS and DFS.

CONCLUSIONS

Skip N2 disease has a similar prognosis to N1 disease and is significantly better than that of non-skip N2 disease in relation to OS and DFS. Skip N2 has a prognostic advantage in patients with the acinar-predominant subtype.

Recommended changes for the 8th edition of the TNM classification for lung cancer-the findings of a single-institution evaluation

BACKGROUND

To evaluate the efficacy of the nodal descriptors and subgroups proposed by International Association for the Study of Lung Cancer (IASLC) in the 8th edition of the TNM classification system and to provide references for future editions.

METHODS

A total of 3,177 patients with non-small cell lung cancer at the Beijing Cancer Hospital were classified based on the following three methods: (I) the N descriptors in the 8th edition of the TNM classification system: N0, N1, N2, and N3; (II) the IASLC-proposed N subgroups: N1a, N1b, N2a1, N2a2, and N2b; (III) our more extensive division method: N1a, N1b, N1c, N2a1, N2a2, N2b1, N2b2, N2c, N3a, and N3b. Five-year survival analysis was performed using the Kaplan-Meier method, and differences between subgroups were evaluated using the log-rank test.

RESULTS

(I) A significant survival difference was found between each adjacent N descriptor; (II) the difference between each adjacent subgroup N descriptor was significant, but the difference between N1b and N2a1 was not; (III) in our proposed method, a significant difference was found between all the subgroups apart from N2a2 and N2b1, N2b1 and N2b2, N2c and N3a, and N3a and N3b.

CONCLUSIONS

The N descriptors in the 8th edition of the tumor, node, and metastasis (TNM) classification system are consistent with our data. Although our more extensive division method could distinguish between patients at different stages, its implementation is complicated; thus, we recommend the implementation of the IASLC-proposed subgroups with the addition of the N1b and N2a1 groups.

[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.

A Comparison of the Currently Used Nodal Stage Classification with the Number of Metastatic Lymph Nodes and the Number of Metastatic Lymph Node Stations for Non-Small Cell Lung Cancer; Which of These Is the Best Prognostic Factor?

Objectives We aimed to compare the currently used nodal staging system (pN) with the number of metastatic lymph node (LN) stations (sN) and the number of metastatic LNs (nN) on survival in patients with NSCLC.

Methods Between 2010 and 2017, 1038 patients resected for NSCLC were analyzed. We performed three-different stratifications of LN status assessment: pN-category (pN0, pN1 and pN2); sN-category (sN0, sN1; one station metastasis, sN2; two-three stations metastases, and sN3; ≥ 4 stations metastasis); nN-category (nN0, nN1; one-three LNs metastasis, nN2; four-six Lns metastasis, and nN3; ≥ 7 LNs metastasis).

Results Five-year survival rate was 70.1% for N0 in all classifications. It was 54.3% for pN1, and 26.4% for pN2 (p < 0.0001). Five-year survival rates for N1, N2, and N3 categories were 54.1%, 42.4% and 16.1% according to sN, and 51.4%, 36.1%, and 7.9% according to nN, respectively (p < 0.0001). In multivariate analysis, sN and nN were independent risk factors such as pN (p < 0.0001). Hazard ratios versus N0 for N1, N2, and N3 were more significant for sN and nN than pN (1.597, 2.176, and, 3.883 for sN, 1.645, 2.658, and, 4.118 for nN, and 1.576, 3.222 for pN, respectively). When the subcategories of sN and nN were divided into pN1 and pN2 subgroups, the anatomic location of the LN involvement lost importance as tumor burden and tumor spreading increased.

Conclusion The number of metastatic LN stations and the number of metastatic LNs are better prognostic factors than currently used nodal classification in NSCLC.

Prognostic relevance of regional lymph-node distribution in patients with N1-positive non-small cell lung cancer: A retrospective single-center analysis

OBJECTIVE

Lymph node (LN) metastases predict survival in patients with non-small cell lung cancer (NSCLC) treated with curative surgery. Nevertheless, prognostic differences within the same nodal (N) status have been reported. Consequently, the International Association for the Study of Lung Cancer (IASLC) proposed to stratify patients with limited nodal disease (pN1) from low (pN1a) to high (pN1b) nodal tumor burden. This study aimed to validate the IASLC proposal in a large single-center surgical cohort of patients with pN1 NSCLC.

MATERIAL AND METHODS

Data from 317 patients with pN1 NSCLC treated between January 2012 and December 2016, were retrospectively analyzed. Associations between distribution of LN metastases and survival were analyzed for different classification models-toward nodal extension (pN1a: one station involved; pN1b: multiple stations involved) and toward location (pN1 in the hilar [LN#10/11] or peripheral zone [LN#12-14]).

RESULTS

Tumor-specific survival (TSS) in the entire pN1 cohort was 67.1% at five years. Five-year TSS rates for pN1a and pN1b patients were comparable (67.6% vs. 66.5%, p = 0.623). Significant survival differences from pN1a to pN1b were observed only in patients with adenocarcinoma histology and completed adjuvant chemotherapy (5-year TSS: pN1a, 80.4% vs. pN1b, 49.6%; p = 0.005). TSS for LN metastases in the hilar zone/peripheral zone or in both zones was 68.2% and 59.9%, respectively (p = 0.068). In multivariate analysis, adjuvant chemotherapy, squamous cell histology, and nodal disease limited to one zone nodal disease were identified as independent beneficial prognostic factors (p < 0.05).

CONCLUSION

pN1 in only one region (hilar or lobar) was associated with better outcome than metastatic affection of both regions after surgery and adjuvant therapy. A stratification towards single (pN1a) and multiple (pN1b) N1-metastases was found of prognostic relevance only in adenocarcinoma. Prospective multicenter analysis of prognostic subgroups in N1 NSCLC is required to evaluate its clinical impact for consideration in future TNM classification.

Prognostic significance of the pattern of pathological N1 lymph node metastases for non-small cell lung cancer

Background

In patients with non-small cell lung cancer (NSCLC) the pathologic lymph node status N1 is a heterogeneous entity, and different forms of lymph node involvement may represent different prognoses. For methodological reasons, the 8th edition of the TNM staging system for NSCLC makes no official changes to the N descriptor. However, there is evidence that different subforms of N1 disease are associated with different prognoses, and it is now recommended that clinicians record the number of affected lymph nodes and nodal stations for further analyses. In this investigation we sought to determine whether patients with different levels and types of N1 lymph node involvement had significantly different 5-year survival rates.

Methods

We retrospectively identified 90 patients with NSCLC (61 men, 29 women), who were treated between 2008 and 2012 and found to have pathologic N1 lymph node involvement and tumor sizes corresponding to T1 or T2. All patients were treated in curative intent with surgical lung resection and systematic mediastinal and hilar lymph node dissection.

Results

The overall 5-year survival rate was 56.3%. In the univariate analysis, lower tumor stage and tumor histology other than large-cell carcinoma were significantly associated with better long-term survival. Patients with solitary lymph node metastases also had longer disease-free survival than those with multiple nodal metastases. In the multivariate analysis, large-cell carcinoma and Union for International Cancer Control (UICC) stage IIB were independently associated with worse survival, while pneumonectomy, compared to lobar or sublobar resection, was independently associated with better survival.

Conclusions

Although we did not observe significant prognostic differences between N1 subcategories within our patient population, other analyses may yield different results. Therefore, these data highlight the need for large, well-designed multicenter studies to confirm the clinical significance of N1 subcategories.

Recommended Change in the N Descriptor Proposed by the International Association for the Study of Lung Cancer: A Validation Study

INTRODUCTION

The International Association for the Study of Lung Cancer recently proposed a new N descriptor by combining the location of metastatic lymph nodes (LNs), nN (single-station versus multiple-station), and absence versus presence of skip metastasis as pN1a, pN1b, pN2a1, pN2a2 and pN2b. This study aimed to evaluate the discriminatory ability and prognostic performance of the proposed N descriptor in a large independent NSCLC cohort.

METHODS

We analyzed 1228 patients who underwent major pulmonary resection for pathological N1 or N2 NSCLC between 2004 and 2014. Survival analysis using the Cox proportional hazard model was performed to assess the prognostic significance of the N descriptor.

RESULTS

From 2004 to 2014, a total of 7437 patients were operated on for NSCLC. Patients pathologically confirmed as having N1 (n = 732) or N2 (n = 496) disease after surgery were included. The median total number of dissected LNs was 24 (range 10-83), and the median number of involved LNs was 2 (range 1-40). The 5-year overall survival rates were 62.6%, 57.0%, 64.7%, 48.4%, and 42.8% for stages N1a, N1b, N2a1, N2a2, and N2b, respectively. Analysis of overall and recurrence-free survival revealed that N2a1 is not sufficiently distinguished from N1a and N1b. In terms of overall survival, N1b is not sufficiently distinguished from N2a2.

CONCLUSION

On the basis of the N descriptor proposed by the International Association for the Study of Lung Cancer, some of the prognostic implications of the five groups overlapped. It would be better to classify similar prognostic groups into three or four groups to divide the group. A large-scale prospective study is needed to validate these N descriptors.

Feasibility of nodal classification for non-small cell lung cancer by merging current N categories with the number of involved lymph node stations

Introduction

The aim of this study was to assess the prognoses of patients with non‐small cell lung cancer (NSCLC) according to the current nodal (N) categories of the tumor, node and metastasis (TNM) classification and the number of involved lymph node stations.

Methods

Five hundred and seventy patients with NSCLC underwent surgery from 1 January 2005 to 31 December 2009 and were analysed retrospectively. Postoperative overall survival was analysed according to two nodal classifications: the current N0, N1, N2 and N3 categories and those based on the number of involved nodal stations: N0, N1a (single N1), N1b (multiple N1), N2a1 (single N2 without N1), N2a2 (single N2 with N1), N2b1 (multiple N2 without N1) and N2b2 (multiple N2 with N1).

Results

Five‐year survival rates were 76.1%, 53.4% and 26.3% for N0, N1 and N2, respectively (P < 0.001). When survival was analysed by the number of involved nodal stations, the groups with significant differences were maintained; otherwise, they were merged, and new codes were assigned as follows for exploratory analyses: NA (N0), NB (N1a), NC (N1b, N2a (i.e., N2a1 and N2a2) and N2b1) and ND (N2b2). Five‐year survival rates were 76.1%, 60.0%, 39.1%, and 11.4% for NA, NB, NC and ND, respectively, and there were significant differences among them. This N classification was an independent prognostic factor in multivariate analyses.

Conclusion

Pending prospective and international validation, it is practical to merge the current N categories with the number of involved lymph node stations when evaluating the postoperative prognosis of NSCLC patients.

A hypothesized TNM staging system based on the number and location of positive lymph nodes may better reflect the prognosis for patients with NSCLC

Background

This study aimed to evaluate the feasibility and prognostic accuracy of incorporating the number of positive lymph nodes (PLN) into the TNM staging system for non-small cell lung cancer (NSCLC) patients.

Methods

We screened a total of 9539 patients with resected stage IA-IIIB non-small cell cancer between 2010 and 2015 from SEER database. The chi-square test was used to compare patient baseline characteristics and the X-tile model was applied to determine cut-off values for the number of PLN (nN). The X-tile model was used to screen three different cut-off values including nN = 0, nN1–3 and nN4-. Univariate and multivariate Cox proportional hazards regression models were used to analyze the influence of different variables on overall survival (OS). Kaplan-Meier and log-rank test were used to compare survival differences.

Results

Based on the nN cutoffs, we conducted the univariate and multivariate Cox proportional hazards regression. The result showed that nN stage was a significant prognostic factor affecting patients' OS (all P <  0.001). We reclassified the seventh edition TNM stages of the enrolled patients with stage IA-IIIB NSCLC according to the 5-year OS rate. Hypothesized TNM substage based on the location and the number of PLN was further calculated. Then we drew survival curves for each substage, including for the current TNM stage and the hypothesized TNM stage. From the comparison of survival curves, we found that the survival curve of each substage of the hypothesized TNM classification was proportional and well distributed compared with the current TNM classification (P <  0.001).

Conclusion

Revised TNM staging integrating locational pN stage and numerical nN stage was a more accurate prognostic determinant in patients with NSCLC.