Limited resection for noninvasive bronchioloalveolar carcinoma diagnosed by intraoperative pathologic examination

Nodule characterization: subsolid nodules

In this review, we focus on the radiologic, clinical, and pathologic aspects primarily of solitary subsolid pulmonary nodules. Particular emphasis will be placed on the pathologic classification and correlative computed tomography (CT) features of adenocarcinoma of the lung. The capabilities of fluorodeoxyglucose positron emission tomography-CT and histologic sampling techniques, including CT-guided biopsy, endoscopic-guided biopsy, and surgical resection, are discussed. Finally, recently proposed management guidelines by the Fleischner Society and the American College of Chest Physicians are reviewed.

Invasiveness and malignant potential of pulmonary lesions presenting as pure ground-glass opacities

PURPOSE

We retrospectively investigated the pathological diagnoses of pulmonary lesions presenting as pure ground-glass opacities (GGOs) to evaluate the risk of invasive malignancy.

METHODS

We examined 191 GGO lesions, including 114 pure GGO and 77 mixed lesions, in 160 patients who underwent resection between January 2008 and December 2010.

RESULTS

Of the 114 pure GGO lesions, 14 (12%) were diagnosed as invasive lung cancer and 16 (14%) as minimally invasive adenocarcinoma. Twenty-one lesions exhibited pleural indentation on high-resolution computed tomography (HRCT), and 5 of these were diagnosed as invasive cancer, indicating an invasive tendency of pure GGO lesions with pleural indentation (odds ratio, 2.64). Of 14 pure GGO lesions positive on positron emission tomography (PET), 8 were diagnosed as invasive lung cancer, indicating an invasive tendency of pure GGO lesions with PET positivity (odds ratio, 16.0; p <0.001; sensitivity, 67%; specificity, 89%).

CONCLUSION

Invasive lung cancer accounted for 12% of the pure GGO lesions. Pure GGO lesions should be carefully monitored by periodic chest computed tomography, and surgical resection is recommended when they exhibit pleural indentation on HRCT or positivity on PET.

Risk factor analysis of locoregional recurrence after sublobar resection in patients with clinical stage IA non-small cell lung cancer

OBJECTIVE

Although lobectomy is the standard surgical procedure for operable non-small cell lung cancer (NSCLC), sublobar resection also has been undertaken for various reasons. The aim of this study was to identify risk factors of locoregional recurrence and poor disease-specific survival in patients with clinical stage IA NSCLC undergoing sublobar resection.

METHODS

We retrospectively reviewed 328 patients with clinical stage IA NSCLC who underwent segmentectomy or wedge resection. Demographic, clinical, and pathologic factors were analyzed using the log-rank test as univariate analyses, and all factors were entered into a Cox proportional hazards regression model for multivariate analyses to identify independent predictors of locoregional recurrence and poor disease-specific survival.

RESULTS

The 5- and 10-year locoregional recurrence-free probabilities were 84.8% and 83.6%, respectively, and the 5- and 10-year disease-specific survivals were 83.6% and 73.6%, respectively. Four independent predictors of locoregional recurrence were identified: wedge resection (hazard ratio [HR], 5.787), microscopic positive surgical margin (HR, 3.888), visceral pleural invasion (HR, 2.272), and lymphatic permeation (HR, 3.824). Independent predictors of poor disease-specific survival were identified as follows: smoking status (Brinkman Index; HR, 1.001), wedge resection (HR, 3.183), microscopic positive surgical margin (HR, 3.211), visceral pleural invasion (HR, 2.553), and lymphatic permeation (HR, 3.223). All 4 predictors of locoregional recurrence also were identified as independent predictors of poor disease-specific survival.

CONCLUSIONS

Segmentectomy should be the surgical procedure of first choice in patients with clinical stage IA NSCLC who are being considered for sublobar resection. Patients having tumors presenting with no suspicious of pleural involvement would be suitable candidates for sublobar resection.

Treatment of stage I and II non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

The treatment of stage I and II non-small cell lung cancer (NSCLC) in patients with good or low surgical risk is primarily surgical resection. However, this area is undergoing many changes. With a greater prevalence of CT imaging, many lung cancers are being found that are small or constitute primarily ground-glass opacities. Treatment such as sublobar resection and nonsurgical approaches such as stereotactic body radiotherapy (SBRT) are being explored. With the advent of minimally invasive resections, the criteria to classify a patient as too ill to undergo an anatomic lung resection are being redefined.

METHODS

The writing panel selected topics for review based on clinical relevance to treatment of early-stage lung cancer and the amount and quality of data available for analysis and relative controversy on best approaches in stage I and II NSCLC: general surgical care vs specialist care; sublobar vs lobar surgical approaches to stage I lung cancer; video-assisted thoracic surgery vs open resection; mediastinal lymph node sampling vs lymphadenectomy at the time of surgical resection; the use of radiation therapy, with a focus on SBRT, for primary treatment of early-stage NSCLC in high-risk or medically inoperable patients as well as adjuvant radiation therapy in the sublobar and lobar resection settings; adjuvant chemotherapy for early-stage NSCLC; and the impact of ethnicity, geography, and socioeconomic status on lung cancer survival. Recommendations by the writing committee were based on an evidence-based review of the literature and in accordance with the approach described by the Guidelines Oversight Committee of the American College of Chest Physicians.

RESULTS

Surgical resection remains the primary and preferred approach to the treatment of stage I and II NSCLC. Lobectomy or greater resection remains the preferred approach to T1b and larger tumors. The use of sublobar resection for T1a tumors and the application of adjuvant radiation therapy in this group are being actively studied in large clinical trials. Every patient should have systematic mediastinal lymph node sampling at the time of curative intent surgical resection, and mediastinal lymphadenectomy can be performed without increased morbidity. Perioperative morbidity and mortality are reduced and long-term survival is improved when surgical resection is performed by a board-certified thoracic surgeon. The use of adjuvant chemotherapy for stage II NSCLC is recommended and has shown benefit. The use of adjuvant radiation or chemotherapy for stage I NSCLC is of unproven benefit. Primary radiation therapy remains the primary curative intent approach for patients who refuse surgical resection or are determined by a multidisciplinary team to be inoperable. There is growing evidence that SBRT provides greater local control than standard radiation therapy for high-risk and medically inoperable patients with NSCLC. The role of ablative therapies in the treatment of high-risk patients with stage I NSCLC is evolving. Radiofrequency ablation, the most studied of the ablative modalities, has been used effectively in medically inoperable patients with small (&lt; 3 cm) peripheral NSCLC that are clinical stage I.

Early-stage pulmonary adenocarcinoma (T1N0M0): a clinical, radiological, surgical, and pathological correlation of 104 cases. The MD Anderson Cancer Center Experience

The recent proposal for histological subtyping of pulmonary adenocarcinoma by predominant pattern and introduction of the terms adenocarcinoma in situ and minimally invasive adenocarcinoma to replace the term bronchioloalveolar carcinoma by the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society has led us to conduct a study of 104 patients with early-stage primary pulmonary adenocarcinoma (T1N0M0), with a view to histological subtype as defined by the new proposal and clinical outcome. None of the clinical parameters of our patient population (type of surgery, age, gender, tumor size, and comorbidities) showed any statistically significant correlation with outcome, except for associated malignancies, which not surprisingly appeared to have a negative impact on survival. In addition, statistical analyses of the histological characteristics to include tumor differentiation and the percentage of a lepidic or bronchioloalveolar component did not show any statistically significant values in terms of survival. Our results failed to show any statistically significant difference of survival between those T1N0M0 adenocarcinomas with a lepidic component and those without, thus questioning the use of terms such as in situ or minimally invasive adenocarcinoma. On the basis of our results, we consider that the outcome for patients with T1N0M0 disease is still best determined by appropriate staging rather than by changes in the pathology nomenclature of adenocarcinoma.

A dominant adenocarcinoma with multifocal ground glass lesions does not behave as advanced disease

BACKGROUND

Invasive lung adenocarcinomas increasingly present with synchronous, multifocal, in situ lesions that appear as ground glass opacities (GGOs). The optimal approach in this circumstance (often nonsmokers) remains unclear. We evaluated a general strategy of anatomic resection of the dominant tumor (DT) and wedge resection of accessible ipsilateral GGOs.

METHODS

This is a retrospective review of 39 patients with suspected multifocal in situ adenocarcinomas and 1 DT in a predominantly Caucasian population. Mean follow-up is 30.7 months.

RESULTS

Forty-nine percent of patients had no or minimal smoking history; 21% were Asian. The resected DT was pathologically "bronchioloalveolar carcinoma" (26%), minimally invasive adenocarcinoma (5%), adenocarcinoma with bronchioloalveolar features (41%), or moderate well-differentiated adenocarcinoma (28%). The p stage of the DT was IA in 20, IB in 15, and IIA in 4, with mean diameter of 2.6 cm. Thirty-two patients (82%) underwent anatomic resection of the DT; 7 (18%) underwent wedge resection. The mean number of GGOs present initially was 2.7 (range, 1 to 7) with a 5.2-mm mean diameter. An unresected nodule increased in size during follow-up in only 9 patients (23%). The mean diameter growth among these was 3.2 mm, with mean doubling time of 49 months. New GGOs (range, 1 to 8) developed in 16 patients (41%), all of which remained at 7 mm or less. Distant metastasis developed in 2 patients (5.2%); only 1 patient has required intervention for progression of a GGO. The overall survival is 100%.

CONCLUSIONS

Patients with limited, multifocal, in situ adenocarcinomas and a clinical N0 DT enjoy prolonged survival with generally anatomic resection of the DT and wedge resection of accessible GGOs. These patients should not be considered to harbor T4 or M1a disease.

Differences in the prognosis of resected lung adenocarcinoma according to the histological subtype: a retrospective analysis of Japanese lung cancer registry data

OBJECTIVES

This study intended to assess the clinicopathological features of the histological subtypes of adenocarcinoma of the lung in a large registry population.

METHODS

The Japanese Joint Committee of Lung Cancer Registry performed a nationwide retrospective registry study on the prognosis and clinicopathological profiles of 11 663 patients who underwent resection for primary lung neoplasm in 2004. The registry data of 7921 (62.5%) patients with adenocarcinoma were analysed regarding the prognosis and clinicopathological features according to the histological subtype of adenocarcinoma. The histological subtypes were defined according to the 1999 World Health Organization classification (third edition), where bronchioloalveolar carcinoma (BAC) is defined as adenocarcinoma with a pure bronchioloalveolar growth pattern without invasion.

RESULTS

The distribution of the histological subtype was acinar in 471 patients (7.5%), papillary in 2004 (32.2%), BAC in 1385 (22.3%), solid adenocarcinoma with mucin in 103 (1.7%) and adenocarcinoma with mixed subtypes (AMS) in 2257 (36.3%). The 5-year overall survival rates according to histological subtype were 63.4% for acinar, 72.9% for papillary, 90.3% for BAC, 54.4% for solid adenocarcinoma with mucin and 73.7% for AMS. While the survival rate in patients with BAC was significantly better than those for the other histological subtypes, acinar and solid adenocarcinoma with mucin had significantly worse prognoses than the other histological subtypes. The histological subtype was an independent predictor of survival in a multivariate analysis (P < 0.001). Regarding BAC, the pathological stage included not only Stage IA/IB (n = 1275; 92.1%), but also Stage II-IV (n = 110; 7.9%). One hundred twenty-five patients (9.0%) with BAC had recurrence, including both local and distant recurrence.

CONCLUSIONS

The histological subtype in adenocarcinoma significantly correlated with the prognosis. In BACs with recurrence or pathological stage II-IV, these tumours might have been classified as invasive adenocarcinoma rather than as BAC. The need for the rigorous pathological evaluation of adenocarcinomas that are considered to be a preinvasive or minimally invasive tumour should be addressed in the new lung adenocarcinoma classification to be proposed by the International Association for the Study of Lung Cancer, the American Thoracic Society and the European Respiratory Society.

IASLC/ATS/ERS International Multidisciplinary Classification of Lung Adenocarcinoma: novel concepts and radiologic implications

In 2011, the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society proposed a new classification for lung adenocarcinoma that included a number of changes to previous classifications. This classification now considers resection specimens, small biopsies, and cytology specimens. Two former histopathologic terms, bronchioloalveolar carcinoma and mixed subtype adenocarcinoma, are no longer to be used. For resection specimens, the new terms of adenocarcinoma in situ and minimally invasive adenocarcinoma are introduced for small adenocarcinomas showing pure lepidic growth and predominantly lepidic growth, with invasion ≤5 mm, respectively. Invasive adenocarcinomas are now classified by their predominant pattern as lepidic, acinar, papillary, and solid; a micropapillary pattern is newly added. This classification also provides guidance for small biopsies and cytology specimens. For adenocarcinomas that include both an invasive and a lepidic component, it is suggested that for T staging the size of the T-factor may be best measured on the basis of the size of the invasive component rather than on the total size of tumors including lepidic components, both on pathologic and computed tomography assessment. This suggestion awaits confirmation in clinical-radiologic trials. An implication for M staging is that comprehensive histologic subtyping along with other histologic and molecular features can be very helpful in determining whether multiple pulmonary nodules are separate primaries or intrapulmonary metastases. In this review article, we provide an illustrated overview of the proposed new classification for lung adenocarcinoma with an emphasis upon what the radiologist needs to know in order to successfully contribute to the multidisciplinary strategic management of patients with this common histologic subtype of lung cancer.

Evaluation of individuals with pulmonary nodules: when is it lung cancer? Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

OBJECTIVES

The objective of this article is to update previous evidence-based recommendations for evaluation and management of individuals with solid pulmonary nodules and to generate new recommendations for those with nonsolid nodules.

METHODS

We updated prior literature reviews, synthesized evidence, and formulated recommendations by using the methods described in the "Methodology for Development of Guidelines for Lung Cancer" in the American College of Chest Physicians Lung Cancer Guidelines, 3rd ed.

RESULTS

We formulated recommendations for evaluating solid pulmonary nodules that measure > 8 mm in diameter, solid nodules that measure ≤ 8 mm in diameter, and subsolid nodules. The recommendations stress the value of assessing the probability of malignancy, the utility of imaging tests, the need to weigh the benefits and harms of different management strategies (nonsurgical biopsy, surgical resection, and surveillance with chest CT imaging), and the importance of eliciting patient preferences.

CONCLUSIONS

Individuals with pulmonary nodules should be evaluated and managed by estimating the probability of malignancy, performing imaging tests to better characterize the lesions, evaluating the risks associated with various management alternatives, and eliciting their preferences for management.

Diagnosis of lung adenocarcinoma in resected specimens: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification

A new lung adenocarcinoma classification has been published by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society. This new classification is needed to provide uniform terminology and diagnostic criteria, most especially for bronchioloalveolar carcinoma. It was developed by an international core panel of experts representing all 3 societies with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons.This summary focuses on the aspects of this classification that address resection specimens. The terms bronchioloalveolar carcinoma and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced, such as adenocarcinoma in situ and minimally invasive adenocarcinoma for small solitary adenocarcinomas with either pure lepidic growth (adenocarcinoma in situ) and predominant lepidic growth with invasion of 5 mm or less (minimally invasive adenocarcinoma), to define the condition of patients who will have 100% or near 100% disease-specific survival, respectively, if they undergo complete lesion resection. Adenocarcinoma in situ and minimally invasive adenocarcinoma are usually nonmucinous, but rarely may be mucinous. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous bronchioloalveolar carcinoma), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous bronchioloalveolar carcinoma), colloid, fetal, and enteric adenocarcinoma.It is possible that this classification may impact the next revision of the TNM staging classification, with adjustment of the size T factor according to only the invasive component pathologically in adenocarcinomas with lepidic areas.

Limited resection and two-staged lobectomy for non-small cell lung cancer with ground-glass opacity

Background

Lung tumors showing ground-glass opacities on high-resolution computed tomography indicate the presence of inflammation, atypical adenomatous hyperplasia, or localized bronchioloalveolar carcinoma. We adopted a two-staged video-assisted thoracoscopic lobectomy strategy involving completion lobectomy for localized bronchioloalveolar carcinoma with an invasive component according to postoperative pathological examination by permanent section after partial resection.

Methods

Forty-one patients with undiagnosed small peripheral ground-glass opacity lesions underwent partial resection from 2001 to 2007 in Hokkaido University Hospital. Localized bronchioloalveolar carcinoma was classified according to the Noguchi classification for adenocarcinoma. Malignant lesions other than Noguchi types A and B were considered for completion lobectomy and systemic mediastinal lymphadenectomy. Perioperative data of completion video-assisted thoracoscopic lobectomies were compared with data of 67 upfront video-assisted thoracoscopic lobectomies for clinical stage IA adenocarcinoma performed during the same period.

Results

Postoperative pathological examination revealed 35 malignant and 6 non-malignant diseases. Histologically, all of the malignant diseases were adenocarcinomas of Noguchi type A (n = 7), B (n = 9), C (n = 18), and F (n = 1). Eleven of 19 patients (58%) with Noguchi type C or F underwent two-staged video-assisted thoracoscopic lobectomy. Three patients refused a second surgery. There was no cancer recurrence. The two-staged lobectomy group had a significantly longer operative time and more blood loss than the upfront lobectomy group. There was no surgical mortality or cancer recurrence.

Conclusions

Two-staged lobectomy for undiagnosed small peripheral ground-glass opacity lesions showed satisfactory oncological results. However, low compliance for and invasiveness of the second surgery are concerns associated with this strategy.

Invasive pulmonary adenocarcinomas versus preinvasive lesions appearing as ground-glass nodules: differentiation by using CT features

PURPOSE

To retrospectively investigate the differentiating computed tomographic (CT) features between invasive pulmonary adenocarcinoma (IPA) and preinvasive lesions appearing as ground-glass nodules (GGNs) in 253 patients.

MATERIALS AND METHODS

This study was approved by the institutional review board. From January 2005 to October 2011, 272 GGNs were pathologically confirmed (179 IPAs and 93 preinvasive lesions) in 253 patients and were included in this study. There were 64 pure GGNs and 208 part-solid GGNs. Preinvasive lesions consisted of 21 atypical adenomatous hyperplasias and 72 adenocarcinomas in situ. To identify the differentiating CT features between IPAs and preinvasive lesions and to evaluate their differentiating accuracy, logistic regression analysis and receiver operating characteristic (ROC) curve analysis were performed, respectively.

RESULTS

In pure GGNs, preinvasive lesions were significantly smaller and more frequently nonlobulated than IPAs (P < .05). Multivariate analysis revealed that lesion size was the single significant differentiator of preinvasive lesions from IPAs (P = .029). The optimal cut-off size for preinvasive lesions was less than 10 mm (sensitivity, 53.33%; specificity, 100%). In part-solid GGNs, there were significant differences in lesion size, solid portion size, solid proportion, margin, border, and pleural retraction between IPAs and preinvasive lesions (P < .05). Multivariate analysis revealed that smaller lesion size, smaller solid proportion, nonlobulated border, and nonspiculated margin were significant differentiators of preinvasive lesions (P < .05), with excellent differentiating accuracy (area under ROC curve, 0.905).

CONCLUSION

In pure GGNs, a lesion size of less than 10 mm can be a very specific discriminator of preinvasive lesions from IPAs. In part-solid GGNs, preinvasive lesions can be accurately distinguished from IPAs by the smaller lesion size, smaller solid proportion, nonlobulated border, and nonspiculated margin.

Approach to the patient with multiple lung nodules

It can be difficult to determine whether a patient with more than a single, "solid" lung nodule suspicious for malignancy is suffering from synchronous primary tumors or intrapulmonary metastasis. For this reason, if resection can be performed an aggressive approach is often warranted after demonstrating no mediastinal nodal disease. Increasing evidence suggests that the survival of a patient with a single, invasive lepidic-predominant adenocarcinoma depends on the stage of the invasive tumor, not on the presumed multiple in situ tumors. A suggested clinical approach to each of these types of multifocal tumors, solid and lepidic, is proposed in this article.

Stereotactic body radiation therapy for the treatment of early-stage minimally invasive adenocarcinoma or adenocarcnioma in situ (formerly bronchioloalveolar carcinoma): a patterns of failure analysis

Introduction

Ongoing prospective trials exploring stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC) often exclude minimally invasive adenocarcinoma or adenocarcnioma in situ, formerly bronchioloalveolar carcinoma (BAC), due to concerns for accurate target delineation on CT. We performed a patterns of failure analysis to compare outcomes between BAC and other NSCLC subtypes.

Methods

One hundred twenty patients with early stage NSCLC were treated with SBRT from 2004–2009. Pathologic confirmation of NSCLC was obtained in 97 patients. Radiotherapy was delivered according to RTOG guidelines. The log-rank test was used to compare outcomes between BAC and other NSCLC.

Results

Median follow-up was 29 months. The median SBRT dose was 5400 cGy. Thirteen patients had radiographically diagnosed BAC and five patients had biopsy confirmed BAC, of which two had both. The three-year local control was 100% for biopsy-proven or radiographically diagnosed BAC (n = 18) and 86% for all other NSCLC subtypes (n = 102) (p = 0.13). Likewise, no significant difference was detected between BAC and other NSCLC for 3-year regional failure (12% vs. 20%, p = 0.45), progression-free survival (57.6% vs. 53.5%, p = 0.84) or overall survival (35% vs. 47%, p = 0.66). There was a trend towards lower three-year rates of freedom from distant failure in patients with any diagnosis of BAC compared to those without (26% vs. 38%, p = 0.053).

Conclusions

Compared to other NSCLC subtypes, BAC appears to have similar patterns of failure and survival after treatment with SBRT, however there may be an increased risk of distant metastases with BAC. RTOG guideline-based target delineation provides encouraging local control rates for patients with BAC.

Recommendations for the management of subsolid pulmonary nodules detected at CT: a statement from the Fleischner Society

This report is to complement the original Fleischner Society recommendations for incidentally detected solid nodules by proposing a set of recommendations specifically aimed at subsolid nodules. The development of a standardized approach to the interpretation and management of subsolid nodules remains critically important given that peripheral adenocarcinomas represent the most common type of lung cancer, with evidence of increasing frequency. Following an initial consideration of appropriate terminology to describe subsolid nodules and a brief review of the new classification system for peripheral lung adenocarcinomas sponsored by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS), six specific recommendations were made, three with regard to solitary subsolid nodules and three with regard to multiple subsolid nodules. Each recommendation is followed first by the rationales underlying the recommendation and then by specific pertinent remarks. Finally, issues for which future research is needed are discussed. The recommendations are the result of careful review of the literature now available regarding subsolid nodules. Given the complexity of these lesions, the current recommendations are more varied than the original Fleischner Society guidelines for solid nodules. It cannot be overemphasized that these guidelines must be interpreted in light of an individual's clinical history. Given the frequency with which subsolid nodules are encountered in daily clinical practice, and notwithstanding continuing controversy on many of these issues, it is anticipated that further refinements and modifications to these recommendations will be forthcoming as information continues to emerge from ongoing research.

Approach to the ground-glass nodule

The detection of ground-glass opacity (GGO) is increasingly common. Sufficient data have been accumulated to formulate recommendations for observation, intervention, and treatment modalities. However, an understanding of many nuances and uncertainties in the available data is needed to avoid making management errors. This article discusses the range of possible entities, risk factors and characteristics that help make a presumptive clinical diagnosis, how often and for how long these should be followed when and how a biopsy should be done, how these lesions should be treated, and how multifocal GGOs should be approached.

Emerging treatment options in the management of non-small cell lung cancer

Lung cancer (LC) has become the leading cancer-related cause of death in the US and in developed European countries in the last decade. Its incidence is still growing in females and in smokers. Surgery remains the treatment of choice whenever feasible, but unfortunately, many patients have an advanced LC at presentation and one-third of potentially operable patients do not receive a tumor resection because of their low compliance for intervention due to their compromised cardiopulmonary functions and other comorbidities. For these patients the alternative therapeutic options are stereotactic radiotherapy or percutaneous radiofrequency. When surgery is planned, an anatomical resection (segmentectomy, lobectomy, bilobectomy, pneumonectomy, sleeve lobectomy) is usually performed; wedge resection (considered as a nonanatomical one) is generally the accepted option for unfit patients. The recent increase in discovering small and peripheral LCs and/or ground-glass opacities with screening programs has dramatically increased surgeons' interest in limited resections. The role of these resections is discussed. Also, recent improvements in molecular biology techniques have increased the chemotherapic options for neoadjuvant LC treatment. The role and the importance of targeted chemotherapy is also discussed.

International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma

INTRODUCTION

Adenocarcinoma is the most common histologic type of lung cancer. To address advances in oncology, molecular biology, pathology, radiology, and surgery of lung adenocarcinoma, an international multidisciplinary classification was sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification is needed to provide uniform terminology and diagnostic criteria, especially for bronchioloalveolar carcinoma (BAC), the overall approach to small nonresection cancer specimens, and for multidisciplinary strategic management of tissue for molecular and immunohistochemical studies.

METHODS

An international core panel of experts representing all three societies was formed with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. A systematic review was performed under the guidance of the American Thoracic Society Documents Development and Implementation Committee. The search strategy identified 11,368 citations of which 312 articles met specified eligibility criteria and were retrieved for full text review. A series of meetings were held to discuss the development of the new classification, to develop the recommendations, and to write the current document. Recommendations for key questions were graded by strength and quality of the evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

The classification addresses both resection specimens, and small biopsies and cytology. The terms BAC and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced such as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure lepidic growth (AIS) or predominant lepidic growth with ≤ 5 mm invasion (MIA) to define patients who, if they undergo complete resection, will have 100% or near 100% disease-specific survival, respectively. AIS and MIA are usually nonmucinous but rarely may be mucinous. Invasive adenocarcinomas are classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous BAC), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous BAC), colloid, fetal, and enteric adenocarcinoma. This classification provides guidance for small biopsies and cytology specimens, as approximately 70% of lung cancers are diagnosed in such samples. Non-small cell lung carcinomas (NSCLCs), in patients with advanced-stage disease, are to be classified into more specific types such as adenocarcinoma or squamous cell carcinoma, whenever possible for several reasons: (1) adenocarcinoma or NSCLC not otherwise specified should be tested for epidermal growth factor receptor (EGFR) mutations as the presence of these mutations is predictive of responsiveness to EGFR tyrosine kinase inhibitors, (2) adenocarcinoma histology is a strong predictor for improved outcome with pemetrexed therapy compared with squamous cell carcinoma, and (3) potential life-threatening hemorrhage may occur in patients with squamous cell carcinoma who receive bevacizumab. If the tumor cannot be classified based on light microscopy alone, special studies such as immunohistochemistry and/or mucin stains should be applied to classify the tumor further. Use of the term NSCLC not otherwise specified should be minimized.

CONCLUSIONS

This new classification strategy is based on a multidisciplinary approach to diagnosis of lung adenocarcinoma that incorporates clinical, molecular, radiologic, and surgical issues, but it is primarily based on histology. This classification is intended to support clinical practice, and research investigation and clinical trials. As EGFR mutation is a validated predictive marker for response and progression-free survival with EGFR tyrosine kinase inhibitors in advanced lung adenocarcinoma, we recommend that patients with advanced adenocarcinomas be tested for EGFR mutation. This has implications for strategic management of tissue, particularly for small biopsies and cytology samples, to maximize high-quality tissue available for molecular studies. Potential impact for tumor, node, and metastasis staging include adjustment of the size T factor according to only the invasive component (1) pathologically in invasive tumors with lepidic areas or (2) radiologically by measuring the solid component of part-solid nodules.

Bronchioloalveolar carcinoma and the significance of invasion: predicting biologic behavior

A resected adenocarcinoma illustrates challenges in diagnosing bronchioloalveolar carcinoma (BAC). Bronchioloalveolar carcinoma is defined by lack of invasion, something that may be difficult to assess in scars. Small (≤0.5 cm) invasive foci have little impact on the good prognosis associated with low-stage tumors. The term microinvasive adenocarcinoma or minimally invasive adenocarcinoma has been proposed for otherwise typical BACs and small invasive foci measuring 0.5 cm or less. Larger areas of invasion are associated with a more aggressive course and more reliably distinguish BAC from other variants of adenocarcinoma. Separating BAC from other forms of adenocarcinoma is important owing to differences in prognosis and emerging therapeutic strategies.

Successful intentional lobectomy for lung cancer after treating contralateral diaphragmatic eventration

Diaphragmatic eventration permanently raises all or part of the hemidiaphragm, thus impairing respiratory function by compressing the ipsilateral lung and mediastinum. A 55-year-old woman had cT1N0M0 lung adenocarcinoma in the right lower lobe and diaphragmatic eventration in the left hemithorax. We repaired the eventration to recover respiratory function, then performed a radical lobectomy with mediastinal lymph node dissection. Pathologically, the tumor was a well-differentiated acinar adenocarcinoma (pT1N0M0 stage IA). She was free from cancer and eventration 18 months later. This is the first known report of a lung cancer patient with impaired respiratory function who underwent an intentional radical lobectomy following repair of contralateral diaphragmatic eventration to recover respiratory function.

Bronchioloalveolar Carcinoma and Minimally Invasive Adenocarcinoma

The most recent WHO classification of lung cancer defines bronchioloalveolar carcinoma (BAC) as a noninvasive carcinoma or adenocarcinoma in situ. However, the use of this terminology is not uniform and does not reflect standardized criteria. As a result, the diagnosis of BAC has been used in association with small, solitary, and well-differentiated adenocarcinoma as well as tumors with advanced clinical stage. At present, there is a growing consensus among specialists in thoracic oncology that BAC or adenocarcinoma in situ is a rare tumor, and the term should be restricted to adenocarcinomas that show a pure lepidic pattern of growth. The amount of invasive component present in a tumor with a predominant lepidic growth pattern has also been under intense scrutiny. The concept of minimally invasive adenocarcinoma is developing in order to differentiate a pure BAC from an invasive adenocarcinoma that still carries an excellent prognosis.