State of the artThe New IASLC-ATS-ERS Lung Adenocarcinoma Classification: What the Surgeon Should Know
Introduction
Lung adenocarcinoma, which is the most frequent histologic subtype of non–small cell lung cancer (NSCLC) encountered by surgeons, is heterogeneous in clinical and radiologic presentation, histologic appearance, surgical outcome, and molecular biological profile.1 Over the past decade, the single most important factor that has helped determine clinical management and prognosis for patients with lung cancer has been TNM staging.2 Although the histologic classification of lung cancer has been periodically revised by the World Health Organization, the last classification, which was published in 2004, had approximately 90% of lung adenocarcinomas classified as a single category—mixed subtype.1
Although there have been several advances over the past decade in defining the molecular alterations within lung adenocarcinomas, some of which have aided in the development of targeted therapies such as EGFR mutation in patients with advanced disease, none of the molecular patterns have proven useful for a uniform classification system of lung adenocarcinoma in surgically resected tumors. There is mounting evidence that suggests that histologic patterns in lung adenocarcinomas can be used to define prognostically variable subsets. With the pressing need for an update, a new classification for lung adenocarcinomas was developed by a joint working group of the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society (IASLC-ATS-ERS) in 2011.1
Section snippets
Development of the IASLC-ATS-ERS Lung Adenocarcinoma Classification
To provide an internationally acceptable histologic classification system that could be applied to define prognostically variable subsets, an international, multidisciplinary panel was developed by the IASLC-ATS-ERS, including pathologists, thoracic surgeons, thoracic medical oncologists, pulmonologists, radiologists, and molecular biologists. The panel members performed a systematic review of the published literature and initially selected 11,368 relevant articles. Of these, 312 articles met
The Proposed IASLC-ATS-ERS Classification of Lung Adenocarcinoma
The proposed IASLC-ATS-ERS classification (Table 1)1 addressed resected tumors and cytology of small biopsies. As a part of the proposed classification, the panel recommended that clinicians stop using the confusing term “bronchioloalveolar carcinoma.” This term has been used for at least 5 different tumors defined in the new classification including noninvasive tumors with atypical pneumocyte proliferation along the preexisting alveolar wall and a variety of invasive adenocarcinomas, including
Correlation Between Histologic Subtypes and Prognosis
We reviewed the published literature that validated the correlation between the newly proposed histologic classification and patient outcomes in at least 150 surgically resected series. We identified 19 published studies that met the criteria (Table 2).3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 In total, 17 studies demonstrated significant differences in patient outcomes among the histologic subtypes,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 17, 18, 19, 20, 21 whereas
Acknowledgment
We would like to thank Alex Torres of the MSK Thoracic Surgery Service for his editorial assistance.
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Prognostic value of complex glandular patterns in invasive pulmonary adenocarcinomas
2022, Human PathologyMachine vision-assisted identification of the lung adenocarcinoma category and high-risk tumor area based on CT images
2022, PatternsCitation Excerpt :According to the classification standard of lung tumors described by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society classification in 2011 as well as the WHO in 2015, lepidic-predominant adenocarcinomas ≤3 cm in size can be classified into (1) adenocarcinoma in situ (AIS), which shows the entirely lepidic growth, (2) minimally invasive adenocarcinoma (MIA) with invasion of no more than 5 mm, and (3) invasive adenocarcinoma (IAC), based on the degree of infiltration.2 It is believed that this classification standard of lung adenocarcinoma in pathophysiology helps improve the predictive ability of clinical outcomes and therapeutic benefits, which are important in the diagnosis.3 In real-world practice, lung adenocarcinoma is usually classified based on the results of pathological examination, which evaluates the degree of infiltration, such as determining the foci of stromal, vascular, and pleural invasion as well as measuring the largest single focus of the invasion and central scans.4
“HRCT predictors of GGO surgical resection: Histopathological and molecular correlation in the era of lung sparing surgery”
2022, Lung CancerCitation Excerpt :The GG pattern found at HRCT scan could reflect, in histologically confirmed lung adenocarcinomas, a lepidic growth behavior with absent or minimal acinar component [10]. According to the new IASLCA/ATS/ERS lung adenocarcinoma classification, pure GGOs are suggestive of pre-invasive lesions: AAH, adenocarcinoma in situ (AIS) or minimally invasive adenocarcinoma (MIA) [11]. However, in some cases, “pure GGOs” can also show an invasive behavior as reported in previous studies [9,10].
The differential prognostic impact of spread through air spaces in early-stage lung adenocarcinoma after lobectomy according to the pT descriptor
2022, Journal of Thoracic and Cardiovascular SurgeryCitation Excerpt :Mediastinal LN dissections that did not meet the aforementioned criteria according to the permanent pathologic report were classified as insufficient. The pathologic stage, predominant histologic subtype of adenocarcinoma, and their histologic grading system with low grade (well differentiated; lepidic predominant), intermediate grade (moderately differentiated; acinar or papillary predominant), and high grade (poorly differentiated; solid or micropapillary predominant) were determined according to the eighth edition of the TNM staging classification for lung cancer,14 the 2015 WHO classification,6 and the 2014 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification system for lung adenocarcinoma.15 Our standard postoperative follow-up strategies were as follows; patients were followed up with contrast-enhanced chest CT scans every 6 months for the first 3 years, and then every 8 months until 5 years postoperatively.
This work was supported, in part, by the International Association for the Study of Lung Cancer Young Investigator Award; National Lung Cancer Partnership, USA–LUNGevity Foundation Research Grant; American Association for Thoracic Surgery Third Edward D. Churchill Research Scholarship; William H. Goodwin and Alice Goodwin, the Commonwealth Foundation for Cancer Research and the Experimental Therapeutics Center; the National Cancer Institute, USA (Grants R21 CA164568-01A1, R21 CA164585-01A1, U54 CA137788, P30 CA008748, and U54 CA132378); and the U.S. Department of Defense, USA (Grants PR101053 and LC110202).