The International Association for the Study of Lung Cancer (IASLC) Staging Project for Lung Cancer: Recommendation to Introduce Spread Through Air Spaces as a Histologic Descriptor in the Ninth Edition of the TNM Classification of Lung Cancer. Analysis of 4061 Pathologic Stage I NSCLC.

INTRODUCTION: Spread through air spaces (STAS) consists of lung cancer tumor cells that are identified beyond the edge of the main tumor in the surrounding alveolar parenchyma. It has been reported by meta-analyses to be an independent prognostic factor in the major histologic types of lung cancer, but its role in lung cancer staging is not established. METHODS: To assess the clinical importance of STAS in lung cancer staging, we evaluated 4061 surgically resected pathologic stage I R0 NSCLC collected from around the world in the International Association for the Study of Lung Cancer database. We focused on whether STAS could be a useful additional histologic descriptor to supplement the existing ones of visceral pleural invasion (VPI) and lymphovascular invasion (LVI). RESULTS: STAS was found in 930 of 4061 of the pathologic stage I NSCLC (22.9%). Patients with tumors exhibiting STAS had a significantly worse recurrence-free and overall survival in both univariate and multivariable analyses involving cohorts consisting of all NSCLC, specific histologic types (adenocarcinoma and other NSCLC), and extent of resection (lobar and sublobar). Interestingly, STAS was independent of VPI in all of these analyses. CONCLUSIONS: These data support our recommendation to include STAS as a histologic descriptor for the Ninth Edition of the TNM Classification of Lung Cancer. Hopefully, gathering these data in the coming years will facilitate a thorough analysis to better understand the relative impact of STAS, LVI, and VPI on lung cancer staging for the Tenth Edition TNM Stage Classification.

Completeness of Resection and Long-Term Survival of Patients Undergoing Resection for Pathologic T3 NSCLC: An International Association for the Study of Lung Cancer Analysis.

INTRODUCTION: Currently, tumors with different histopathologic characteristics and oncologic outcomes comprise the T3 category of the eight edition TNM classification for lung cancers. To better understand the T3 category, we evaluated completeness of resection and long-term survival in patients undergoing resection for T3 NSCLC. METHODS: The International Association for the Study of Lung Cancer 1999 to 2010 database was queried for patients with pathologic T3N0M0 NSCLC who underwent lobectomy or pneumonectomy. The primary outcome evaluated was overall survival (OS) stratified by T3 descriptors and completeness of resection. RESULTS: Of 1448 patients with T3N0M0 tumors, 1187 (82.0%) had a single descriptor defining them as T3. T3 tumors with chest wall infiltration (CWI) or parietal pleura infiltration (PL3) had the highest rates of incomplete resection (9.8% and 8.4%, respectively), and those classified as T3 by size only had the lowest rate of incomplete resection (2.9%). Individual T3 descriptors were associated with significant differences in OS (p = 0.005). When tumors with similar survival and complete resection rates were grouped, patients with T3 tumors characterized by size or the presence of a separate nodule (SN) in the same lobe had better 5-year OS than patients with tumors characterized by PL3 or CWI (size/SN 60% versus CWI/PL3 53%, p = 0.017) independent of completeness of resection. CONCLUSIONS: Significant differences in 5-year OS were associated with size, SN, PL3, or CWI T3 descriptors. Subdividing pathologic T3N0M0 tumors according to the presence or absence of CWI or PL3 may increase the prognostic accuracy of tumor staging.

The International Association for the Study of Lung Cancer Staging Project: Methods and Guiding Principles for the Development of the Ninth Edition TNM Classification.

INTRODUCTION: Stage classification provides a consistent and concise nomenclature about the anatomic extent of the cancer. This is a fundamental cornerstone in the management of patients; it enables reporting results and facilitates comparing one treatment to another and judging how closely clinical trial results apply to an individual patient. A nomenclature must be relatively static; however, periodical refinement is needed to adjust to a changing landscape of clinical relevance. Changes must be well justified and thoughtfully developed to maintain the ability to communicate clearly and facilitate comparisons across time. METHODS: For thoracic malignancies (lung, pleura, thymus, and esophagus), the International Association for the Study of Lung Cancer (IASLC) has leveraged its worldwide multidisciplinary reach, permitting a sophisticated approach to this process. Refinement of stage classification for the ninth edition of TNM is underway; this article describes the approach adopted by the IASLC Staging and Prognostic Factors Committee. RESULTS: Key guiding principles include the ability to maintain communication over time, a classification that discriminates homogeneous cohorts of tumors consistently across the world in multiple settings, treatment approaches, and patient characteristics, including clinical relevance and practical applicability. The IASLC has again assembled a large international database to permit multifaceted analysis. Providing confidence that the classification performs consistently in multiple settings, treatments, and patients requires consistent discrimination in multiple subset analyses. Although observed outcomes of patients in the 2011 to 2019 database are essential, considerations about how the classification will be used are also important to ensure clinical relevance and applicability. CONCLUSIONS: The strategy developed by the Staging and Prognostic Factors Committee is carefully designed to provide useful refinements to the stage classification of thoracic malignancies for the ninth edition of TNM classification of cancers.