Clinical implications of uncertain resection in scenarios of metastasis of the highest or most distant mediastinal lymph node station following surgical treatment of non-small-cell lung cancer

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.

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.

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.

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

Patients with N2 non-small cell lung cancer (NSCLC) were heterogeneous groups and required further stratification. The International Society for the Study of Lung Cancer (IASLC) divided N2 into three sub-stages: N2 at a single station without N1 involvement (N2a1), N2 at a single station with N1 involvement (N2a2), and N2 at multiple stations (N2b). These new descriptors significantly distinguished the overall survival (OS), disease-free survival (DFS), and recurrence pattern of patients with different N2 sub-stages. The OS and DFS of N2a1 were not sufficiently distinguished from N1 at multiple stations (N1b). The OS and DFS of N2a2 were intermediate between those of N2a1 and N2b. Current evidence did not support the further subdivision of the N2b. The main recurrence pattern of N2a1, N2a2 and N2b were distant metastasis, and the risks of distant metastasis increased successively. N2a1 patients were at low risk of locoregional recurrence, which could not be reduced by postoperative radiotherapy (PORT). N2a2 and N2b patients had a similar higher risk of locoregional recurrence, which could be reduced to a similar level of N2a1 patients by PORT.
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Uncertain resection of highest mediastinal lymph node positive among pN2 non-small cell lung cancer patients: survival analysis of postoperative radiotherapy and driver gene mutations

BACKGROUND AND PURPOSE

The role of postoperative radiotherapy (PORT) in uncertain resection of pN2 non-small cell lung cancer (NSCLC) with highest mediastinal lymph node positive has not been determined. We aim to evaluate the effect of PORT and driver gene mutation status (DGMS) on survival in such patients.

METHODS

140 selected patients were grouped according to whether they received PORT and their DGMS. Locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), disease-free survival (DFS), and overall survival (OS) of each group were evaluated by Kaplan-Meier analyses. COX regression was used to evaluate the effects of various factors on DFS and OS.

RESULTS

Of 140 patients, thirty-four patients (24.3%) received PORT, and forty (28.6%) had positive driver gene mutation status (DGp). PORT significantly prolonged LRFS (p = 0.002), DFS (p = 0.019) and OS (p = 0.02), but not DMFS (p = 0.062). By subgroup analysis, in patients with negative driver gene mutation status (DGn), those receiving PORT had notably longer LRFS (p = 0.022) and DFS (p = 0.033), but not DMFS (p = 0.060) or OS (p = 0.215), compared to those not receiving PORT. Cox analysis showed that the number of positive lymph nodes (PLNs) and administration of PORT were independent prognostic factors of DFS, and pathology, PLNs, and DGMS may be prognostic factors of OS (all p < 0.05).

CONCLUSION

Postoperative radiotherapy may improve locoregional recurrence-free and disease-free survival in patients with pN2 NSCLC with positive highest mediastinal lymph nodes, while driver gene mutation status impacted OS significantly. Only patients with positive driver gene mutations experienced significant overall survival benefits from postoperative radiotherapy.

Prognostic evaluation of the proposed residual tumor classification in a Chinese non-small cell lung cancer population

BACKGROUND

This study aimed to validate the R classification including uncertain resection (R-un) proposed by the International Association for the Study of Lung Cancer (IASLC) in a Chinese non-small cell lung cancer (NSCLC) population.

METHODS

The study retrospectively investigated a 2009-2013 single-institutional NSCLC resection cohort in China. After reclassification, recurrence-free survival (RFS) and overall survival (OS) were calculated using survival analyses and compared with those using the 2005 version IASLC R classification.

RESULTS

Under the proposed stratification, 3819 (72.1%) individuals were classified as R0, 1371 (25.9%) as R-un, 71 (1.3%) as R1, and 32 (0.6%) as R2. The 5-year OS probabilities for the R0, R-un, and R1/R2 groups were 71%, 46%, and 34%, respectively. The prognostic stratification remained significant in the fully adjusted Cox models (p < 0.001). Compared with the original classification, Harrell's concordance index of reclassification improved significantly, from 0.508 to 0.679 for RFS and from 0.510 to 0.692 for OS (RFS: p = 0.007; OS: p = 0.001). The survival analysis showed that R-un patients with highest mediastinal lymph node station metastasis had significantly worse survival than R0 patients with mediastinal nodal metastasis (RFS: 44 vs. 36 months, hazard ratio [HR]: 1.29, p < 0.001; OS: 59 vs. 50 months, HR: 1.34, p < 0.001). Cox proportional hazards regression analysis showed that highest mediastinal lymph node station metastasis was an independent risk factor for RFS (HR: 1.22) and OS (HR: 1.25).

CONCLUSIONS

The proposed R classification showed valid prognostic stratification, including highest mediastinal nodal station metastasis.

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.