Towards optimal pathologic staging of resectable non-small cell lung cancer

Survival After Mediastinal Node Dissection, Systematic Sampling, or Neither for Early Stage NSCLC

INTRODUCTION

The American College of Surgeons Oncology Group Z0030 found no survival difference between patients with early stage NSCLC who had mediastinal nodal dissection or systematic sampling. However, a meta-analysis of 1980 patients in five randomized controlled trials from 1989 to 2007 associated better survival with nodal dissection. We tested the survival impact of the extent of nodal dissection in curative-intent resections for early stage NSCLC in a population-based observational cohort.

METHODS

Resections for clinical T1 or T2, N0 or nonhilar N1, M0 NSCLC in four contiguous United States Hospital Referral Regions from 2009 to 2019 were categorized into mediastinal nodal dissection, systematic sampling, and "neither" on the basis of of the evaluation of lymph node stations. We compared demographic and clinical characteristics, perioperative complication rates, and survival after assessing statistical interactions and confounding.

RESULTS

Of the 1942 eligible patients, 18% had nodal dissection, 6% had systematic sampling, and 75% had an intraoperative nodal evaluation that met neither standard. In teaching hospitals, nodal dissection was associated with a lower hazard of death than "neither" resections (0.57 [95% confidence interval: 0.41-0.79]) but not systematic sampling (0.74 [0.40-1.37]) after adjusting for multiple comparisons. There was no significant difference in hazard ratios at nonteaching institutions (p > 0.3 for all comparisons). Perioperative complication rates were not significantly worse after mediastinal nodal dissection or systematic sampling, compared with "neither," (p > 0.1 for all comparisons).

CONCLUSIONS

In teaching institutions, mediastinal nodal dissection was associated with superior survival over less-comprehensive pathologic nodal staging. There was no survival difference between teaching and nonteaching institutions, a finding that warrants further investigation.

Association of Pathologic Nodal Staging Quality With Survival Among Patients With Non-Small Cell Lung Cancer After Resection With Curative Intent

Importance

Pathologic nodal stage is the most significant prognostic factor in resectable non-small cell lung cancer (NSCLC). The International Association for the Study of Lung Cancer NSCLC staging project revealed intercontinental differences in N category-stratified survival. These differences may indicate differences not only in cancer biology but also in the thoroughness of the nodal examination.

Objective

To determine whether survival was affected by sequentially more stringent definitions of pN staging quality in a cohort of patients with NSCLC after resection with curative intent.

Design

This observational study used the Mid-South Quality of Surgical Resection cohort, a population-based database of lung cancer resections with curative intent. A total of 2047 consecutive patients who underwent surgical resection at 11 hospitals with at least 5 annual lung cancer resections in 4 contiguous US Dartmouth hospital referral regions in northern Mississippi, eastern Arkansas, and western Tennessee (>90% of the eligible population) were included. Resections were performed from January 1, 2009, through January 25, 2016. Survival was evaluated with the Kaplan-Meier method and Cox proportional hazards models.

Exposures

Eight sequentially more stringent pN staging quality strata included the following: all patients (group 1); those with complete resections only (group 2); those with examination of at least 1 mediastinal lymph node (group 3); those with examination of at least 10 lymph nodes (group 4); those with examination of at least 3 hilar or intrapulmonary and at least 3 mediastinal lymph nodes (group 5); those with examination of at least 10 lymph nodes, including at least 1 mediastinal lymph node (group 6); those with examination of at least 1 hilar or intrapulmonary and at least 3 mediastinal nodal stations (group 7); and those with examination of at least 1 hilar or intrapulmonary lymph node, at least 10 total lymph nodes, and at least 3 mediastinal nodal stations (group 8).

Main Outcomes and Measures

N category-stratified overall survival.

Results

Of the total 2047 patients (1046 men [51.1%] and 1001 women [48.9%]; mean [SD] age, 67.0 [9.6] years) included in the analysis, the eligible analysis population ranged from 541 to 2047, depending on stringency. Sequential improvement in the N category-stratified 5-year survival of pN0 and pN1 tumors was found from the least stringent group (0.63 [95% CI, 0.59-0.66] for pN0 vs 0.46 [95% CI, 0.38-0.54] for pN1) to the most stringent group (0.71 [95% CI, 0.60-0.79] for pN0 vs 0.60 [95% CI, 0.43-0.73] for pN1). The pN1 cohorts with 3 or more mediastinal nodal stations examined had the most striking survival improvements. More stringently defined mediastinal nodal examination was associated with better separation in survival curves between patients with pN1 and pN2 tumors.

Conclusions and Relevance

The prognostic value of pN stratification depends on the thoroughness of examination. Differences in thoroughness of nodal staging may explain a large proportion of intercontinental survival differences. More thorough nodal examination practice must be disseminated to improve the prognostic value of the TNM staging system. Future updates of the TNM staging system should incorporate more quality restraints.

Assessment of adequacy of intraoperative nodal staging and factors influencing the lack of its compliance with recommendations in the surgical treatment of non-small cell lung cancer (NSCLC)

Background

Adequate pathological status of lymph nodes sampled during resection of NSCLC determines prognosis and decides on further therapeutic actions. The areas of analysis are the factors affecting evaluation of pN accuracy, and the convergence of recommendations with actual intraoperative sampling of lymph nodes.

Methods

The data of 3,215 patients with NSCLC consecutively operated with the intention of radical resection in 2007-2017, were analyzed. Accuracy of nodal sampling and influencing factors were compared with Union for International Cancer Control (UICC) guidelines, which recommend that to confirm pN0 status at least six lymph nodes/stations free of the disease must be removed. Three should be sampled from mediastinum (including subcarinal) and three from N1 stations.

Results

A significant number of patients were found to have an adequate staging, especially after 2009, in terms of recommended quantity of nodes/nodal stations (P<0.0001). Age ≥64 (P=0.048), left side (P<0.0001), sublobar resection (P<0.0001), T1 tumors (P=0.019) are the factors affecting inadequacy of staging. Patients with inaccurate staging were found to have a considerably lower pN1 (7.2% vs.15.9%, P<0.001) and pN2 (9.7% vs.13.4%, P<0.001) status. Survival of patients with inadequate staging were found to be significantly worse (P=0.0002), which resulted in worse survival of those patients in stage I (P=0.00004), stage II (P=0.023) and stage III (P=0.031) of NSCLC.

Conclusions

UICC recommendations led to an increased adequacy of nodal sampling. The factors affecting insufficient number of sampled nodes include advanced age, left side, sublobar resections and T1 stage. Inaccuracy of intraoperative nodal staging results in incorrect prognosis.

Prognostic value of lymph node ratio in patients with pathological N1 non-small cell lung cancer: a systematic review with meta-analysis

BACKGROUND

Non-small cell lung cancer (NSCLC) patients with N1 disease have variable outcomes, and additional prognostic factors are needed. The number of positive lymph nodes (LNs) has been proposed as a prognostic indicator. However, the number of positive LNs depends on the number of LNs examined from the resection specimen. The lymph node ratio (LNR) can circumvent this limitation. The purpose of this study is to evaluate LNR as a predictor of survival and recurrence in patients with pathologic N1 NSCLC.

METHODS

We systematically reviewed studies published before March 17, 2016, on the prognostic value of LNR in patients with pathologic N1 NSCLC. The hazard ratios (HRs) and their 95% confidence intervals (CIs) were used to combine the data. We also evaluated heterogeneity and publication bias.

RESULTS

Five studies published between 2010 and 2014 were eligible for this systematic review with meta-analysis. The total number of patients included was 6,130 ranging from 75 to 4,004 patients per study. The combined HR for all eligible studies evaluating the overall survival (OS) and disease-free survival (DFS) of N1 LNR in patients with pathologic N1 NSCLC was 1.53 (95% CI: 1.22-1.85) and 1.64 (95% CI: 1.19-2.09), respectively. We found no heterogeneity and publication bias between the reports.

CONCLUSIONS

LNR is a worthy predictor of survival and cancer recurrence in patients with pathological N1 NSCLC.

Improving lung cancer outcomes by improving the quality of surgical care

Surgical resection remains the most important curative treatment modality for non-small cell lung cancer, but variations in short- and long-term surgical outcomes jeopardize the benefit of surgery for certain patients, operated on by certain types of surgeons, at certain types of institutions. We discuss current understanding of surgical quality measures, and their role in promoting understanding of the causes of outcome disparities after lung cancer surgery. We also discuss the use of minimally invasive surgical resection approaches to expand the playing field for surgery in lung cancer care, and end with a discussion of the future role of surgery in a world of alternative treatment possibilities.

Measuring improvement in populations: implementing and evaluating successful change in lung cancer care

Improving quality of care in lung cancer, the leading cause of cancer death worldwide and in the United States, is a major public health challenge. Such improvement requires accurate and meaningful measurement of quality of care. Preliminary indicators have been derived from clinical practice guidelines and expert opinions, but there are few standard sets of quality of care measures for lung cancer in the United States or elsewhere. Research to develop validated evidence-based quality of care measures is critical in promoting population improvement initiatives in lung cancer. Furthermore, novel research designs beyond the traditional randomized controlled trials (RCTs) are needed for wide-scale applications of quality improvement and should extend into alternative designs such as quasi-experimental designs, rigorous observational studies, population modeling, and other pragmatic study designs. We discuss several study design options to aid the development of practical, actionable, and measurable quality standards for lung cancer care. We also provide examples of ongoing pragmatic studies for the dissemination and implementation of lung cancer quality improvement interventions in community settings.

The impact of a novel lung gross dissection protocol on intrapulmonary lymph node retrieval from lung cancer resection specimens

Although thorough pathologic nodal staging provides the greatest prognostic information in patients with potentially curable non-small cell lung cancer, N1 nodal metastasis is frequently missed. We tested the impact of corrective intervention with a novel pathology gross dissection protocol on intrapulmonary lymph node retrieval. This study is a retrospective review of consecutive lobectomy, or greater, lung resection specimens over a period of 15 months before and 15 months after training pathologist's assistants on the novel dissection protocol. One hundred forty one specimens were examined before and 121 specimens after introduction of the novel dissection protocol. The median number of intrapulmonary lymph nodes retrieved increased from 2 to 5 (P<.0001), and the 75th to 100th percentile range of detected intrapulmonary lymph node metastasis increased from 0 to 5 to 0 to 17 (P=.0003). In multivariate analysis, the extent of resection, examination period (preintervention or postintervention), and pathologic N1 (vs N0) status were most strongly associated with a higher number of intrapulmonary lymph nodes examined. A novel pathology dissection protocol is a feasible and effective means of improving the retrieval of intrapulmonary lymph nodes for examination. Further studies to enhance dissemination and implementation of this novel pathology dissection protocol are warranted.