Prognostic value of the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society lung adenocarcinoma classification on death and recurrence in completely resected stage I lung adenocarcinoma

Advances in lung adenocarcinoma classification: a summary of the new international multidisciplinary classification system (IASLC/ATS/ERS)

Due to advances in the understanding of lung adenocarcinoma since the advent of its 2004 World Health System classification, an international multidisciplinary panel [sponsored by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS)] has recently updated the classification system for lung adenocarcinoma, the most common histologic type of lung cancer. Here, we summarize and highlight the new criteria and terminology, certain aspects of its clinical relevance and its potential treatment impact, and future avenues of research related to the new system.

Implementing the new IASLC/ATS/ERS classification of lung adenocarcinomas: results from international and Chinese cohorts

A new histologic classification of lung adenocarcinoma was proposed by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) in 2011 to provide uniform terminology and diagnostic criteria for multidisciplinary strategic management. This classification proposed a comprehensive histologic subtyping (lepidic, acinar, papillary, micropapillary, and solid pattern) and a semi-quantitative assessment of histologic patterns (in 5% increments) in an effort to choose a single, predominant pattern in invasive adenocarcinomas. The prognostic value of this classification has been validated in large, independent cohorts from multiple countries. In patients who underwent curative-intent surgery, those with either an adenocarcinoma in situ (AIS) or a minimal invasive adenocarcinoma have nearly 100% disease-free survival and are designated "low grade tumors". For invasive adenocarcinomas, the acinar and papillary predominant histologic subtypes were usually designated as "intermediate grade" while the solid and micropapillary predominant histologic subtypes were designated "high grade" tumors; this was based on the statistic difference of overall survival. This classification, coupled with additional prognostic factors [nuclear grade, cribriform pattern, high Ki-67 labeling index, thyroid transcription factor-1 (TTF-1) immunohistochemistry, immune markers, and (18)F-fluorodeoxyglucose uptake on positron emission tomography (PET)] that we have published on, could further stratify patients into prognostic subgroups and may prove helpful for individual patient care. With regard to Chinese oncologists, the implementation of this new classification only requires hematoxylin and eosin (H&E) stained slides and basic pathologic training, both of which require no additional costs. More importantly, this new classification system could provide informative data for better selection and stratification of clinical trials and molecular studies.

The new IASLC/ATS/ERS lung adenocarcinoma classification from a clinical perspective: current concepts and future prospects

The new the International Association for the Study of Lung Cancer (IASLC)/the American Thoracic Society (ATS)/the European Respiratory Society (ERS) pathologic classification of lung cancer has markedly changed the pathologic diagnosis of lung adenocarcinoma. This classification deals with many aspects that directly affect clinical practice, and opens new gateways for future research. By means of a multidisciplinary approach, it differs significantly from the former 2004 the World Health Organization (WHO) classification, which was mainly written by pathologist. The present review, in line with the consensus article, is divided in two components: the diagnosis and classification of lung adenocarcinoma in resection specimens and the diagnosis of lung cancer in small biopsies and cytology. Resection specimens are currently classified according to the predominant histologic pattern after comprehensive subtyping in 5% increments. This approach has led to the addition of new pathologic subtypes [adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and micropapillary predominant adenocarcinoma)] and to the discontinuation of some heterogeneous entities included in the former 2004 WHO classification (mixed subtype adenocarcinoma and bronchioloalveolar carcinoma). Overall, these changes have resulted in a better stratification of lung adenocarcinoma tumors in more homogeneous morphologic, clinical and biological subgroups. Pathologic subtyping has demonstrated prognostic utility in resected stage I-III patients, and recent data support their predictive role for the benefit of adjuvant chemotherapy. Moreover, comprehensive pathologic subtyping may potentially affect TNM staging and surgical management or early-stage tumors. On the other hand, for the first time, the novel pathologic classification provides standardized terminology and diagnostic criteria of small biopsies and cytology. Criteria are proposed not only for adenocarcinoma but also for other histologies, but special emphasis was put on the distinction between adenocarcinoma and squamous-cell carcinoma due to its major clinical implications. This review outlines the main issues of the new lung adenocarcinoma classification from a clinical perspective. We describe the different pathologic subtypes in resection specimens, with their most relevant clinical implications. Further on, we address the new terminology and diagnostic criteria for lung adenocarcinomas in small specimens, oriented to their importance for the management and treatment of metastatic lung cancer patients. Finally, we discuss some unanswered questions and relevant issues for the near future.

Association of IASLC/ATS/ERS Histologic Subtypes of Lung Adenocarcinoma With Epidermal Growth Factor Receptor Mutations in 320 Resected Cases

BACKGROUND

The relationships between the subtypes defined by the new international histologic classification of lung adenocarcinoma (IASLC/ATS/ERS) and epidermal growth factor receptor (EGFR) mutations were studied.

PATIENTS AND METHODS

We retrospectively reviewed 320 patients with lung adenocarcinoma (162 women, 158 men; mean age, 69 years) who had undergone complete resection, focusing on the new histologic subtypes and EGFR mutations. The clinical stage was IA in 196 patients, IB in 95, IIA in 10, IIB in 10, IIIA in 6, and IV in 3.

RESULTS

The most prevalent subtype was papillary (35.0%), followed by acinar (29.4%), lepidic (13.1%), solid (7.2%), adenocarcinoma in situ (6.6%), minimally invasive adenocarcinoma (6.3%), micropapillary (1.6%), and invasive mucinous adenocarcinoma (1.0%). These subtypes were predictive for both postoperative disease-free and overall survival. EGFR mutations, detected in 40.6% of all cases, were most frequent in acinar (48.4%), followed by minimally invasive adenocarcinoma (45.0%) and papillary (43.8%). They were least frequent in the solid subtype (17.4%). EGFR mutation status did not affect postoperative disease-free or overall survival.

CONCLUSION

The outcome after complete resection for lung adenocarcinoma was predicted by the proposed subtype classification. Because EGFR mutations were found in all subtypes, mutation analyses are essential to identify patients with postoperative relapse who would benefit from EGFR-tyrosine kinase inhibitor therapy.

Prognostic implication of predominant histologic subtypes of lymph node metastases in surgically resected lung adenocarcinoma

The International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) proposed a new classification for lung adenocarcinoma (AD) based on predominant histologic subtypes, such as lepidic, papillary, acinar, solid, and micropapillary; this system reportedly reflects well outcomes of patients with surgically resected lung AD. However, the prognostic implication of predominant histologic subtypes in lymph nodes metastases is unclear so far. In this study, we compared predominant subtypes between primary lung tumors and lymph node metastatic lesions in 24 patients with surgically treated lung adenocarcinoma with lymph node metastases. Additionally, we analyzed prognostic implications of these predominant histologic subtypes. We observed several discordance patterns between predominant subtypes in primary lung tumors and lymph node metastases. Concordance rates were 22%, 64%, and 100%, respectively, in papillary-, acinar-, and solid-predominant primary lung tumors. We observed that the predominant subtype in the primary lung tumor (HR 12.7, P = 0.037), but not that in lymph node metastases (HR 0.18, P = 0.13), determines outcomes in patients with surgically resected lung AD with lymph node metastases.

The new IASLC-ATS-ERS lung adenocarcinoma classification: what the surgeon should know

In 2011, a new histologic classification of lung adenocarcinomas was proposed from a joint working group of the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society, based on the recommendation of an international and multidisciplinary panel. This classification proposed a method of comprehensive histologic subtyping (lepidic, acinar, papillary, micropapillary, and solid pattern) based on semiquantitative assessment of histologic patterns (in 5% increments), with the ultimate goal of choosing a single, predominant pattern. Prognostic subsets could then be described for the classification. Patients with completely resected adenocarcinoma in situ and minimally invasive adenocarcinomas experienced low risk of recurrence. Patients with micropapillary or solid predominant tumors have a high risk of recurrence or cancer-related death. Patients with acinar and papillary predominant tumors comprise an intermediate-risk group. Herein, we review the outline of the proposed International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society classification, a summary of published validation studies of this new classification, and then discuss the key surgical issues; we mainly focused on limited resection as an adequate treatment for early-stage lung adenocarcinomas, as well as preoperative and intraoperative diagnoses. We also review the published studies that identified the importance of histologic subtypes in predicting recurrence, both rates and patterns, in early-stage lung adenocarcinomas. This new classification for the most common type of lung cancer is useful for surgeons, as its implementation would require only hematoxylin-and-eosin histology slides, which is the common type of stain used in hospitals. It can be implemented with routine pathology evaluation and with no additional costs.

Risk factors of recurrence for resected T1aN0M0 invasive lung adenocarcinoma: a clinicopathologic study of 177 patients

Background

This study aimed at identifying risk factors of recurrence for completely resected pathologic T1aN0M0 lung adenocarcinomas.

Methods

We reviewed the records of 177 T1aN0M0 invasive adenocarcinoma patients, and re-classified achieved surgical specimens according to the new International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) lung adenocarcinoma classification. Impact on recurrence-free survival (RFS) for age, gender, smoking history, lymphovascular invasion (LVI) and new classification was analyzed by log-rank test and Cox regression. Two existing prognostic grouping schemes of new classification were compared, and subsequently, the correlation of high-grade group in the better prognostic grouping model with clinical data was investigated statistically.

Results

The 5-year recurrence-free rate was 83.7%. The LVI and new adenocarcinoma classification were significantly associated with 5-year RFS (P = 0.012; P = 0.022, respectively). The designation of papillary predominant subtype in the low-grade group, along with lepidic- and acinar predominant subtype had more prognostic significance than the model of combining papillary-, solid- and micropapillary predominant subtypes as the high-grade group (P = 0.005 versus P = 0.181). This high-grade group has increased risk of recurrence in a multivariate Cox regression (adjusted HR 2.815, 95% CI: 1.239 to 6.397, P = 0.013), and is associated significantly more with male gender (adjusted OR 2.214, 95% CI: 1.050 to 4.668, P = 0.037), and, with borderline significance, the presence of LVI (adjusted OR 2.091, 95% CI: 0.938 to 4.662, P = 0.071).

Conclusions

Our results showed that the solid- and micropapillary predominant subtype of IASLC/ATS/ERS classification remains the only risk factor for post-operative recurrence of T1aN0M0 adenocarcinomas, suggesting that they can be indicators of aggressive tumor behaviors.

Correlation of survival and EGFR mutation with predominant histologic subtype according to the new lung adenocarcinoma classification in stage IB patients

Background

A new lung adenocarcinoma classification proposed by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) has recently been published. This study aimed to investigate the utility of the new histological classification for identifying the prognostic subtypes of adenocarcinomas in stage IB patients.Correlations between the classification and the presence of epidermal growth factor receptor (EGFR) mutation status was also studied.

Methods

One hundred and thirty-six patients with stage IB lung adenocarcinoma operated on in Zhejiang Cancer Hospital were identified between 2002 and 2011. Patients overall survival and disease-free survival were calculated using Kaplan-Meier and Cox regression analyses. EGFR mutations were detected using the amplification refractory mutation system.

Results

A total of 136 cases were included in current study, of which 38 were papillary predominant, 39 were acinar predominant, 22 were micropapillary predominant, 21 were lepidic predominant subtypes, 14 were solid predominant, and 2 were variants of invasive adenocarcinoma. Patients with micropapillary- and solid-predominant tumors had the lowest five-year disease-free survival (28.4 and 36.7%, respectively). Univariate and multivariate analysis showed that the micropapillary-predominant subtype was an independent predictor of disease-free survival (P = 0.0041 and 0.048, respectively), but not overall survival (P = 0.175 and 0.214, respectively). EGFR mutations were significantly associated with the micropapillary-predominant subtype patients (P = 0.0026). The EGFR mutation frequency is lower in the solid-predominant subtype than other subtypes (P = 0.0508).

Conclusions

The predominant subtype in the primary tumor was associated with prognosis in resected stage IB lung adenocarcinoma. The EGFR mutation frequency of micropapillary-predominant subtype is higher than other subtypes.

Predictive value of the international association for the study of lung cancer/American Thoracic Society/European Respiratory Society classification of lung adenocarcinoma in tumor recurrence and patient survival

PURPOSE

This study investigated the pattern of recurrence of lung adenocarcinoma and the predictive value of histologic classification in resected lung adenocarcinoma using the new International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) classification system.

PATIENTS AND METHODS

Histologic classification of 573 patients undergoing resection for lung adenocarcinoma was determined according to the IASLC/ATS/ERS classification system, and the percentage of each histologic component (lepidic, acinar, papillary, micropapillary, and solid) was recorded. The pattern of recurrence of those components and their predictive value were investigated.

RESULTS

The predominant histologic pattern was significantly associated with sex (P < .01), invasive tumor size (P < .01), T status (P < .01), N status (P < .01), TNM stage (P < .01), and visceral pleural invasion (P < .01). The percentage of recurrence was significantly higher in micropapillary- and solid-predominant adenocarcinomas (P < .01). Micropapillary- and solid-predominant adenocarcinomas had a significantly higher possibility of developing initial extrathoracic-only recurrence than other types (P < .01). The predominant pattern group (micropapillary or solid v lepidic, acinar, or papillary) was a significant prognostic factor in overall survival (OS; P < .01), probability of freedom from recurrence (P < .01), and disease-specific survival (P < .01) in multivariable analysis. For patients receiving adjuvant chemotherapy, solid-predominant adenocarcinoma was a significant predictor for poor OS (P = .04).

CONCLUSION

In lung adenocarcinoma, the IASLC/ATS/ERS classification system has significant prognostic and predictive value regarding death and recurrence. Solid-predominant adenocarcinoma was also a significant predictor in patients undergoing adjuvant chemotherapy. Prognostic and predictive information is important for stratifying patients for aggressive adjuvant chemoradiotherapy.

Updating the 2011 International Association for the Study of Lung Cancer classification of lung adenocarcinoma: main priorities and implications for clinicians

SUMMARY: 

The classification of adenocarcinoma was revised by the International Association for the Study of Lung Cancer, the American Thoracic Society and the European Respiratory Society in 2011. In the face of advances of medical therapy in advanced stage disease, these groups sought to improve prognostication and to standardize reporting protocols. A discussion of recent alterations in terminology is undertaken. Included with this is clarification of terminology used small biopsy and cytology specimens. In addition, it will be discussed how an architectural-based classification can be used to assess prognosis and how this applies staging and potential patient management. Several studies have confirmed the effectiveness and reproducibility of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification on lung adenocarcinoma. In addition, there is increasing evidence of clinical application in early stage lung adenocarcinoma. While there may be potential revision in the future, the classification provides better and more standardized information for both clinicians and researchers.

Histological subtypes of solitary pulmonary nodules of adenocarcinoma and their clinical relevance

OBJECTIVE

To explore the histological subtypes of solitary pulmonary nodules (SPNs) of invasive adenocarcinoma and their clinical relevance.

METHODS

A total of 188 patients with pathologically confirmed invasive adenocarcinoma in our hospital from January 2007 to December 2011 were enrolled in this study. In accordance with the new classification of lung adenocarcinoma, all the histological sections were reviewed and classified, and the clinical data were collected and analyzed.

RESULTS

Of these 188 patients who had been initially diagnosed as SPNs of adenocarcinoma, there were 6 cases of lepidic predominant adenocarcinoma (LPA), 71 cases of acinar predominant adenocarcinoma (APA), 74 cases of papillary predominant adenocarcinoma (PPA), 15 cases of micorpapillary predominant adenocarcinoma (MPA), and 22 cases of solid predominant adenocarcinoma (SPA) with mucin production. The incidence of lymph node metastasis was 80.0% and 81.8% in MPA and SPA, respectively, which was significantly higher than those in LPA, APA, and PPA (all P<0.01). The incidence of LPA was 83.3% (5/6) in women, which was significantly higher than that in men (P=0.037).

CONCLUSIONS

According to the new classification, MPA and SPA have high incidence of lymph node metastasis. LPA is more likely to occur in women. Sub-typing of the lung adenocarcinoma based on the newest international classification criteria is helpful to identify the clinical features of this disease.

Impact of the IASLC/ATS/ERS classification in pN0 pulmonary adenocarcinomas: a study with radiological-pathological comparisons and survival analyses

The aim of this study was: (1) to compare the new pathological findings as detected by the IASLC/ATS/ERS classification with the traditional radiological features in pulmonary pN0 adenocarcinomas, (2) to evaluate their prognostic significance on overall survival (OS). A total of 42 surgically resected pN0 pulmonary adenocarcinomas were analyzed. On CT scans, the following radiological data were recorded: sphericity, predominant margins, cavitation and bronchogram, attenuation and percentage of ground glass opacity (GGO). On pathological examination, tumors were categorized according to the IASLC/ATS/ERS classification; Sica score and grade, pathological stage, tumor major axis, pleural invasion, vascular and lymphatic invasion, peritumoral lymphoid infiltration, and cytological features were also determined. Clinical follow up was available in 37 cases (range 1-117 months). Radiologically, 31 solid and 11 semisolid tumors were found. Morphologically, 2 minimally invasive and 40 invasive adenocarcinomas were diagnosed. In radiological-pathological comparisons, (1) the acinar pattern was higher in tumors with solid attenuation and low GGO (p=0.018); (2) the lepidic pattern was more elevated in tumors with high GGO (p=0.012). In multivariate survival analyses with stage, predominant margins on CT scans (p=0.036) and Sica score (p=0.028) significantly affected OS. This study confirms the validity of the new classification of pulmonary adenocarcinomas in radiological-pathological comparisons and underlines the importance of both radiological and pathological findings in correctly identifying their prognostic features.