Grade of Stromal Invasion in Small Adenocarcinoma of the Lung

Quantitative CT analysis of pulmonary ground-glass opacity nodules for the distinction of invasive adenocarcinoma from pre-invasive or minimally invasive adenocarcinoma

Objectives

We aimed to analyze the CT findings of ground-glass opacity nodules diagnosed pathologically as adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and invasive adenocarcinoma in order to investigate whether quantitative CT parameters enable distinction of invasive adenocarcinoma from pre-invasive or minimally invasive adenocarcinoma.

Methods

We reviewed CT images and pathologic specimens from 191 resected ground-glass opacity nodules with little or no solid component at CT. Nodule size, volume, density, mass, skewness/kurtosis, and CT attenuation values at the 2.5^th–97.5^th percentiles on histogram, and texture parameters (uniformity and entropy) were assessed from CT datasets.

Results

Of 191 tumors, 38 were AISs (20%), 61 were MIAs (32%), and 92 (48%) were invasive adenocarcinomas. Multivariate logistic regression analysis helped identify the 75^th percentile CT attenuation value (P = 0.04) and entropy (P<0.01) as independent predictors for invasive adenocarcinoma, with an area under the receiver operating characteristic curve of 0.780.

Conclusion

Quantitative analysis of preoperative CT imaging metrics can help distinguish invasive adenocarcinoma from pre-invasive or minimally invasive adenocarcinoma.

The correlation of the International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) classification with prognosis and EGFR mutation in lung adenocarcinoma

BACKGROUND

The purpose of this study was to validate the prognostic effect and the frequency of mutations in the gene expressing epidermal growth factor receptor (EGFR) in lung adenocarcinoma of Japanese patients, on the basis of the new adenocarcinoma classification proposed by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society.

METHODS

The new classification was used to reclassify 486 adenocarcinomas. The percentage of each histopathologic subtype and the predominant pattern were determined. EGFR mutation was also investigated. The relationship between these results and clinicopathologic backgrounds was investigated statistically.

RESULTS

No patients with adenocarcinoma in situ or minimally invasive adenocarcinoma died within the follow-up periods, followed by patients with lepidic predominant. Patients with papillary or acinar predominant, or invasive mucinous adenocarcinoma, showed almost similar overall survival (OS). The patients with solid predominant and micropapillary predominant showed the worst OS. Multivariate analysis showed that the new classification was an independent predictor of OS. The frequency of EGFR mutation was adenocarcinoma in situ (62%), minimally invasive adenocarcinoma (60%), lepidic (77%), acinar (49%), papillary (50%), solid (28%), micropapillary (43%), and invasive mucinous adenocarcinoma (0%).

CONCLUSIONS

This new adenocarcinoma classification is a very useful predictive marker to plan and determine a therapeutic strategy for lung adenocarcinoma.

Prognostic significance of adenocarcinoma in situ, minimally invasive adenocarcinoma, and nonmucinous lepidic predominant invasive adenocarcinoma of the lung in patients with stage I disease

According to the IASLC/ATS/ERS classification, the lepidic predominant pattern consists of 3 subtypes: adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and nonmucinous lepidic predominant invasive adenocarcinoma. We reviewed tumor slides from 1038 patients with stage I lung adenocarcinoma, recording the percentage of each histologic pattern and measuring the invasive tumor size. Tumors were classified according to the IASLC/ATS/ERS classification: 2 were AIS, 34 MIA, and 103 lepidic predominant invasive. Cumulative incidence of recurrence (CIR) was used to estimate the probability of recurrence. Patients with AIS and MIA experienced no recurrences. Patients with lepidic predominant invasive tumors had a lower risk for recurrence (5-y CIR, 8%) than nonlepidic predominant tumors (n=899; 19%; P=0.003). Patients with >50% lepidic pattern tumors experienced no recurrences (n=84), those with >10% to 50% lepidic pattern tumors had an intermediate risk for recurrence (n=344; 5-y CIR, 12%), and those with ≤10% lepidic pattern tumors had the highest risk (n=610; 22%; P<0.001). CIR was lower for patients with ≤2 cm tumors than for those with >2 to 3 cm tumors (for both total and invasive tumor size), with the difference more pronounced for invasive tumor size (5-y CIR, 13% vs. 21% [total size; P=0.022] and 12% vs. 27% [invasive size; P<0.001]). Most patients with lepidic predominant adenocarcinoma who experienced a recurrence had potential risk factors, including sublobar resection with close margins (≤0.5 cm; n=2), 20% to 30% micropapillary component (n=2), and lymphatic or vascular invasion (n=2). It therefore may be possible to identify lepidic predominant adenocarcinomas that carry a low or high risk for recurrence.

Can image analysis on high-resolution computed tomography predict non-invasive growth in adenocarcinoma of the lung?

PURPOSE

Preoperative radiological predictions of pathological invasiveness must be objective and reproducible in addition to being accurate when considering limited surgery for early lung cancer.

METHODS

Two cohorts were used for the analysis. Two independent observers traced lesion edges and measured areas and proportions of solid component on tumor images with the largest diameter by high resolution computed tomography images and "Image J" software.

RESULTS

The value of the intraclass correlation was 0.997 (95% confidence interval [CI], 0.996-0.998) for the area of solid component and 0.979 (95%CI, 0.958-0.986) for the proportion of solid component, suggesting such parameters were reliable in terms of reproducibility. Az value was 0.898 (95%CI, 0.842-0.953) for the area of solid component and 0.882 (95%CI, 0.816-0.949) for the proportion of solid component, demonstrating 2 parameters were both highly predictive of non-invasive adenocarcinoma. The optimal prediction of non-invasive adenocarcinoma with a cut-off value of 7.5 mm(2) for the area of solid component resulted in a sensitivity of 85.3% and specificity of 86.2% in Cohort 1 and a sensitivity of 66.7% and specificity of 88.5% in Cohort 2.

CONCLUSION

Image analysis using "Image J" software was promising for predicting non-invasive adenocarcinoma with its limited inter-observer variability and high predictive performance.

Pure ground-glass opacity neoplastic lung nodules: histopathology, imaging, and management

OBJECTIVE

The purpose of this article is to discuss histologic diagnosis of pure pulmonary ground-glass opacity nodules (GGNs), high-resolution CT (HRCT) findings and pathologic correlation, and management.

CONCLUSION

When pure GGNs are greater than 15 mm in diameter with nodularity or have high pixel attenuation (>-472 HU), the nodules are more likely to be invasive adenocarcinomas. Sublobar resection with a secured safety margin and without nodal dissection is performed for HRCT-suggested pure-GGN invasive adenocarcinomas and has a 100% 5-year survival rate.

Correlations between tumor stroma characters and dynamic enhanced MDCT findings in nodular pulmonary adenocarcinoma

OBJECTIVE

This study aimed to evaluate correlations between tumor stroma characters and dynamic contrast-enhanced computed tomographic (CT) findings in nodular pulmonary adenocarcinoma.

METHODS

Thirty-three patients with nodular pulmonary adenocarcinoma underwent dynamic contrast-enhancement CT scan before surgery. CT findings include wash-in, wash-out, and distribution of enhancement. The proportion of invasive and noninvasive stroma in tumor was calculated.

RESULTS

Invasive and noninvasive stroma proportion in tumor was correlated positively with wash-in and wash-out enhancement, respectively.

CONCLUSIONS

Tumor stroma proliferation may explain the pathologic basis of CT dynamic enhancement and be a useful prognostic factor of pulmonary adenocarcinoma.

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.

Persistent pure ground-glass opacity lung nodules ≥ 10 mm in diameter at CT scan: histopathologic comparisons and prognostic implications

BACKGROUND

Little is known about the histopathology and prognosis of persistent pure ground-glass opacity nodules (GGNs) of ≥ 10 mm in diameter. We aimed to compare the morphologic features of persistent pure GGNs of ≥ 10 mm in diameter at thin-section CT (TSCT) scan with histopathology and patient prognosis.

METHODS

A total of 46 resected GGNs that were evaluated with TSCT scan and followed up for ≥ 3 years were included in this study. Correlations between histopathology (adenocarcinoma in situ [AIS], minimally invasive adenocarcinoma [MIA], and invasive adenocarcinoma) and CT scan characteristics were examined. CT scan and clinicodemographic data were investigated by univariate and multivariate analyses to identify features that helped distinguish invasive adenocarcinoma from AIS or MIA. Disease recurrence was also evaluated.

RESULTS

The nodules included 19 AISs (41%), nine MIAs (20%), and 18 invasive adenocarcinomas (39%). On univariate analysis, the presence of air bronchogram (P = .012), size of nodule (P = .032, cutoff = 16.4 mm in diameter), and mass of nodule (P = .040, cutoff = 0.472 g) were significant factors that differentiated invasive adenocarcinoma from AIS or MIA. On multivariate analysis, size (P = .010) and mass of nodule (P = .016) were significant determinants for invasive adenocarcinoma. There were no cases of recurrence during a follow-up period of ≥ 3 years after surgical resection.

CONCLUSIONS

In persistent pure GGNs of ≥ 10 mm in diameter, the size and mass of the nodule are determinants of invasive adenocarcinoma, for which surgical resection leads to excellent prognosis.

New IASLC/ATS/ERS classification and invasive tumor size are predictive of disease recurrence in stage I lung adenocarcinoma

INTRODUCTION

The purpose of this study is to analyze and validate the prognostic impact of the new lung adenocarcinoma (ADC) classification proposed by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society and invasive tumor size in stage I lung ADC of Japanese patients.

METHODS

We reclassified 191 stage I ADCs according to the new classification. The percentage of each histological subtype and the predominant type were determined. In addition, both total tumor size and invasive tumor size were examined. The relationship between these results and clinicopathological backgrounds was investigated statistically.

RESULTS

The 5-year disease-free survival (DFS) of adenocarcinoma in situ and minimally invasive adenocarcinoma was 100%; lipidic-predominant ADCs, 94.9%; papillary-predominant ADCs, 85.4%; acinar-predominant ADCs, 89.7%; and solid-predominant ADCs, 54%. The predominant growth pattern was significantly correlated with DFS (p < 0.001, overall). With regard to tumor size, total tumor size was not correlated with DFS (p = 0.475, overall), however, invasive tumor size was significantly correlated with DFS (≤ 0.5 cm/ > 0.5 cm, ≤ 1 cm/ >1 cm, ≤ 2 cm/>2 cm, ≤ 3 cm/ >3 cm, 100%/91.5%/85.9%/80.8%/66.7%% in 5-year DFS) (p = 0.006, overall). A multivariate analysis showed solid-predominant and invasive tumor size were independent predictors of increased risk of recurrence (solid versus nonsolid: hazard ratio = 4.08, 95% confidence interval:1.59-10.5, p = 0.003; invasive tumor size: hazard ratio = 2.04, 95% confidence interval:1.14-3.63, p = 0.016).

CONCLUSION

: The new International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society ADC classification and invasive tumor size are very useful predictors of recurrence of stage I ADCs in Japanese patients.

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.

Pathologic classification of adenocarcinoma of lung

Recently, the 1999/2004 World Health Organization (WHO) classification of adenocarcinoma became less useful from a clinical standpoint as most adenocarcinomas belonged to the mixed subtype and the term bronchioloalveolar carcinoma (BAC) gave rise to much confusion among clinicians. For these reasons a new adenocarcinoma classification was introduced in 2011 by a joint working group of the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS). This represents an international, multidisciplinary effort joining pathologists, molecular biologists, pulmonary physicians, thoracic oncologists, radiologists, and thoracic surgeons. Currently, a distinction is made between pre-invasive lesions, minimally invasive and invasive lesions. The confusing term BAC is not used anymore and new subcategories include adenocarcinoma in situ and minimally invasive adenocarcinoma. Several aspects of this classification are discussed with main emphasis on its correlation with imaging techniques and its impact on diagnosis, treatment and prognosis. On chest computed tomography (CT) a distinction is made between solid and subsolid nodules, the latter comprising ground glass opacities (GGO), and partly solid lesions. Several studies incorporating CT and positron emission tomographic (PET) data show a good imaging-pathologic correlation. With the implementation of screening programs early lung cancer has become a hotly debated topic and sublobar resection is currently reconsidered for early lesions without lymph node involvement. This new classification will also have an impact on the TNM classification. Thoracic surgeons will continue to play a major role in the application, evaluation and further refinement of this new adenocarcinoma classification.

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.

The new 2011 international association for the study of lung cancer/american thoracic society/european respiratory society classification of lung adenocarcinoma in resected specimens: clinicopathologic relevance and emerging issues

Pathologists play an increasingly important role in personalized medicine for patients with lung cancer as a result of the newly recognized relationship between histologic classification and molecular change. In 2011, the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) proposed a new architectural classification for invasive lung adenocarcinomas to provide uniform terminology and diagnostic criteria. This review highlighted the evolution of the classification of lung adenocarcinomas in resected specimens with special respect to both histologic subtyping and invasion. Histologic subtyping of lung adenocarcinoma has been updated based on five major predominant patterns. New concepts of adenocarcinoma in situ and minimally invasive adenocarcinomas have been introduced to define the condition of patients who are expected to have excellent survival. Although the new IASLC/ATS/ERS classification has promising clinical relevance, significant clarification remains necessary for the definitions of subtyping and invasion. More precise definitions and subsequent better education on the interpretation of terminology will be helpful for future studies.

Naked cuticle Drosophila 1 expression in histologic subtypes of small adenocarcinoma of the lung

Background

Naked cuticle Drosophila 1 (NKD1) has been related to non-small cell lung cancer in that decreased NKD1 levels have been associated with both poor prognosis and increased invasive quality.

Methods

Forty cases of lung adenocarcinoma staged as Tis or T1a were selected. Cases were subclassified into adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and small adenocarcinoma (SAD). Immunohistochemical studies for NKD1 were performed.

Results

Forty samples comprised five cases of AIS (12.5%), eight of MIA (20.0%), and 27 of SAD (67.5%). AIS and MIA showed no lymph node metastasis and 100% disease-free survival, whereas among 27 patients with SAD, 2 (7.4%) had lymph node metastasis, and 3 (11.1%) died from the disease. Among the 40 cases, NKD1-reduced expression was detected in 8 (20%) samples, whereas normal expression was found in 15 (37.5%) and overexpression in 17 (42.5%). Loss of NKD1 expression was significantly associated with lymph node metastasis (p=0.001). All cases with predominant papillary pattern showed overexpression of NKD1 (p=0.026).

Conclusions

Among MIA and SAD, MIA had better outcomes than SAD. Down-regulated NKD1 expression was closely associated with nodal metastasis, and overexpression was associated with papillary predominant adenocarcinoma.

Validation of the IASLC/ATS/ERS lung adenocarcinoma classification for prognosis and association with EGFR and KRAS gene mutations: analysis of 440 Japanese patients

INTRODUCTION

This study aimed to validate the utility of the new histological classification proposed by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS) for identifying the prognostic subtypes of adenocarcinomas in Japanese patients; correlations between the classification and the presence of EGFR or KRAS mutation status were also investigated.

METHODS

We retrospectively reviewed 440 patients with lung adenocarcinoma, who underwent resection. The tumors were classified according to the IASLC/ATS/ERS classification. EGFR and KRAS mutations were detected using the established methods.

RESULTS

Five-year disease-free survival rates were: 100% for adenocarcinoma in situ (n = 20) and minimally invasive adenocarcinoma (n = 33), 93.8% for lepidic-predominant adenocarcinoma (n = 36), 88.8% for invasive mucinous adenocarcinoma (n = 10), 66.7% for papillary-predominant adenocarcinoma (n = 179), 69.7% for acinar-predominant adenocarcinoma (n = 61), 43.3% for solid-predominant adencoarcinoma (n = 78), and 0% for micropapillary-predominant adenocarcinoma (n = 19). Multivariate analysis revealed that the new classification was an independent predictor of disease-free survival. EGFR and KRAS mutations were detected in 90 cases (53.9%) and 21 cases (13.3%), respectively; EGFR mutations were significantly associated with adenocarcinoma in situ, minimally invasive adenocarcinoma, lepidic- and papillary-predominant adenocarcinoma, and KRAS mutations adenocarcinomas with mucinous tumor subtypes.

CONCLUSIONS

We found that the IASLC/ATS/ERS classification identified prognostic histologic subtypes of lung adenocarcinomas among Japanese patients. Histologic subtyping and molecular testing for EGFR and KRAS mutations can help predict patient prognosis and select those who require adjuvant chemotherapy.

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.

Bronchioloalveolar invasion in non-small cell lung cancer is associated with expression of transforming growth factor-β1

Background

Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) with fibrous stromal invasion are newly introduced subtypes of small lung adenocarcinoma. AIS is a small localized adenocarcinoma in which growth is restricted to neoplastic cells along preexisting alveolar structures without fibrous stromal invasion. In MIA, by contrast, tumor cells have infiltrated the myofibroblastic stroma. Transforming growth factor (TGF)-β is known to be produced by progressor tumors, and excessive TGF-β contributes to a pathological excess of tissue fibrosis. TGF-β1 is the most abundant isoform, and its expression is a key event fostering tumor invasion and metastasis. We therefore analyzed the relationship between TGF-β1 expression and clinicopathological microinvasion in patients with small lung adenocarcinoma.

Methods

The study participants were 45 patients who underwent curative surgery for AIS and MIA 3 cm or less in size. Those tumors were assessed based on immunohistochemical staining using anti-TGF-β1 antibody. The TGF-β1 status was assessed immunohistochemically using the Allred 8-unit system.

Results

The rates of TGF-β1 positivity in the AIS and MIA groups were 27.3% and 65.2%, respectively (P <0.05). The median of Allred score was 0.5 (range 0–5) in the AIS group and 3.0 (range 0–6) in the MIA group (P = 0.0017).

Conclusions

We suggest that TGF-β1 expression is likely to be significantly stronger in patients with MIA than in those with AIS, and the increased expression may be associated with minimal invasion and infiltration of the myofibroblastic stroma.

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.

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.

Clinical relevance of the new IASLC/ERS/ATS adenocarcinoma classification

In 2011, recommendations for a multidisciplinary classification of lung adenocarcinoma were published under the auspices of the International Association for the Study of Lung Cancer, the American Thoracic Society and the European Respiratory Society. The review was considered necessary due to emerging data on the radiological features, genetics and therapeutic approaches to lung adenocarcinoma, all underpinned by expanding the knowledge of the pathology of this common tumour. The existing WHO classification of 2004 was not really fit for this multidisciplinary focus on the disease. This review describes the recommendations made on the reporting of surgically resected lung cancers according to their predominant pattern, and argues the case for replacing the term bronchioloalveolar carcinoma (WHO 1999 and 2004 definition) with adenocarcinoma in situ and for the introduction of minimally invasive adenocarcinoma. There is also a discussion of diagnosis of non-small-cell lung carcinomas in the small biopsy or cytology setting, a practice that was inadequately addressed in WHO 2004, yet this is much more relevant to most pathologists' daily practice because 85% or so of adenocarcinomas are never resected. Predictive immunohistochemistry, used correctly, can reduce non-specific diagnosis to less than 10% of the cases. Finally, there is an overview of the emerging data on therapeutically relevant lung adenocarcinoma genetics, considering targetable mutations that are now the focus of much activity. The clinical relevance of these changes is discussed.

Alteration of the E-Cadherin/β-Catenin Complex Is an Independent Poor Prognostic Factor in Lung Adenocarcinoma

Background

Epithelial-mesenchymal transition (EMT) is an important step in the invasion and progression of cancer and in the development of chemoresistance by cancer cells.

Methods

To address the clinical significance of the EMT pathway in lung adenocarcinoma and the association of the pathway with histological subtype, we examined 193 surgically resected lung adenocarcinoma samples for the expression of representative EMT-related proteins (E-cadherin, β-catenin, and vimentin) by immunohistochemistry. Histological subtypes were classified according to the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification. The results for EMT-related protein expression were analyzed for correlation with clinicopathological features and with survival.

Results

The loss of E-cadherin expression and aberrant β-catenin expression were significantly associated with larger tumor size, pleural invasion, lymphatic/vascular invasion, and advanced pathological stage (p<0.05). The alteration of the E-cadherin/β-catenin complex was least frequently observed in the lepidic-predominant group, but these associations were not statistically significant. In the multivariate analysis, altered E-cadherin/β-catenin complex expression was found to be an independent poor prognostic factor (p=0.017; hazard ratio, 1.926; 95% confidence interval, 1.119 to 3.314).

Conclusions

The alteration of the expression of the E-cadherin/β-catenin complex was associated with aggressive tumor behavior in lung adenocarcinoma.

Radical treatment of non-small cell lung cancer during the last 5 years

The management of non-small cell lung cancer (NSCLC) has continued to improve over the last 5 years due to advances in surgery, radiological staging, combined modality therapies and advances in radiation technology. We have an updated staging classification (7th Edition American Joint Committee on Cancer staging) and now in 2011, a new histology classification introducing the concepts of adenocarcinoma in situ and minimally invasive adenocarcinoma. This classification has profound surgical implications as the role of limited resection is reconsidered for early stage lesions. Surgery is curative in early stage disease. The role of surgery in locally advanced NSCLC remains controversial. The principal aim is a complete resection as this will determine long-term prognosis. Intraoperative staging of lung cancer is extremely important to determine the extent of resection according to the tumour and nodal status. Systematic nodal dissection is generally advocated to obtain accurate intraoperative staging and to help decide on adjuvant therapy. Radiotherapy currently plays a major role in the management of lung cancer as most patients are not surgical candidates due to disease stage, fitness and co-morbidities. In the last 5 years we have seen continuing optimisation of chemo-radiotherapy combinations and technological advances including the development of image guided radiotherapy (IGRT), stereotactic ablative body radiotherapy (SABR) and intensity modulated radiotherapy (IMRT). Quality of life evaluation is becoming increasingly important and should be considered when deciding on a specific treatment, especially in a multimodality setting.

Antimigratory Effects of the Methanol Extract from Momordica charantia on Human Lung Adenocarcinoma CL1 Cells

Momordica charantia has been found to exhibit anticancer activity, in addition to its well-known therapeutic functions. We have demonstrated that the leaf extract of Momordica charantia (MCME) induces apoptosis in several human cancer cells through caspase- and mitochondria-dependent pathways. In this study, a different susceptibility to MCME was found in human lung adenocarcinoma CL1 cells with different metastatic ability, leading to the significant difference of cell viability and invasiveness between MCME-treated CL1-0 and CL1-5 cells. MCME was found to upregulate the expression of Wnt-2 and affect the migratory and invasive ability of CL1 cells through suppressed MMP-2 and MMP-9 enzymatic activities. We proposed that MCME mediates inhibition against migration of CL1 cells by reducing the expression and activation of Src and FAK to decrease the expression of downstream Akt, β-catenin, and MMPs.

Distinctive histopathological features of lepidic growth predominant node-negative adenocarcinomas 3-5 cm in size

INTRODUCTION

Adenocarcinoma of the lung is a morphologically heterogeneous group of tumors which includes a variable portion of different histologic subtype components: lepidic growth (LG), and acinar, papillary and solid subtypes. Among these, LG is a non-invasive component which is one of the major histological subtypes in small-sized adenocarcinoma (2 cm or less). However, in large adenocarcinomas (3-5 cm in size), the clinicopathological significance of LG components remains unclear.

METHODS

A series of 135 lung adenocarcinomas 3-5 cm in size, without lymph node involvement, were reviewed and classified according to their percentage of LG components. We examined the correlation between the percentage of LG components and clinicopathological factors of these tumors.

RESULTS

There were 41 (30.4%) tumors with 50% or more LG (LG-predominant group). Female gender (p=0.039), smoking history of <20 pack-years (p=0.039), absence of pleural invasion (p=0.003), and absence of vascular invasion (p<0.001) were significantly more frequently observed in the LG-predominant group. LG-predominant tumors showed a significantly higher percentage of non-cancerous cell collapse area to tumor area compared with non-LG predominant tumors (p<0.001). The outcome of the LG-predominant type patients was significantly better than that of the non-LG predominant type patients in both recurrence-free survival (p<0.001) and overall survival (p<0.001). Multivariate analysis showed that LG-predominant tumor to be an independent favorable prognostic factor (HR=0.285, 95% confidence interval: 0.148-0.547, p=0.014).

CONCLUSION

Node-negative LG-predominant adenocarcinomas of 3-5 cm in size showed less invasiveness compared to non-LG predominant tumors. And LG-predominant type patients had excellent surgical outcome.

Radiographic and pathological analysis of small lung adenocarcinoma using the new IASLC classification

AIM

To analyse the correlation between computed tomography (CT) findings of small lung adenocarcinomas and the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society Classification of Lung Adenocarcinoma.

MATERIALS AND METHODS

A retrospective review of 300 lung adenocarcinoma lesions (size ≤20 mm) after surgical resection in 295 consecutive patients was performed. Tumours were defined as air-containing type if the ratio of the maximum dimension of the tumour on mediastinal windows to the maximum dimension of the tumour on lung windows was ≤50%, and as solid-density type if the ratio was >50%. The incidence between CT findings (air bronchogram, vascular involvement, pleural tags, notches, and spiculation) and pathological findings were investigated.

RESULTS

Of the 142 air-containing lesions, 114 were adenocarcinoma in situ (AIS), 28 were minimally invasive adenocarcinoma (MIA), and none of the lesions were invasive adenocarcinoma. Of the 158 solid-density lesions, 30 were AIS, 24 were MIA, and 104 were invasive adenocarcinoma. Notches and pleural tags were commonly observed in cases of invasive adenocarcinoma (p < 0.05).

CONCLUSIONS

In the air-containing type of small lung adenocarcinomas, AIS and MIA were observed but no cases of invasive adenocarcinoma were found. The presence of notches and pleural tags were a significant factor in invasive adenocarcinoma.

Radiologic implications of the 2011 classification of adenocarcinoma of the lung

Now the leading subtype of lung cancer, adenocarcinoma received a new classification in 2011. For tumors categorized previously as bronchioloalveolar carcinoma (BAC), criteria and terminology had not been uniform, so the 2011 classification provided four new terms: (a) adenocarcinoma in situ (AIS), representing histopathologically a small (≤3-cm), noninvasive lepidic growth, which at computed tomography (CT) is usually nonsolid; (b) minimally invasive adenocarcinoma, representing histopathologically a small (≤3-cm) and predominantly lepidic growth that has 5-mm or smaller invasion, which at CT is mainly nonsolid but may have a central solid component of up to approximately 5 mm; (c) lepidic predominant nonmucinous adenocarcinoma, representing histopathologically invasive adenocarcinoma that shows predominantly lepidic nonmucinous growth, which at CT is usually part solid but may be nonsolid or occasionally have cystic components; and (d) invasive mucinous adenocarcinoma, histopathologically showing lepidic growth as its predominant component, which at CT varies widely from solid to mostly solid to part solid to nonsolid and may be single or multiple (when multifocal, it was formerly called multicentric BAC). In addition, new histopathologic subcategories of acinar, papillary, micropapillary, and solid predominant adenocarcinoma are now described, all as nonmucinous, predominantly invasive, may include a small lepidic component, and at CT are usually solid but may include a small nonsolid component. The micropapillary subtype has a poorer prognosis than the other subtypes. In addition, molecular genetic correlations for the subcategories of adenocarcinoma of the lung are now a topic of increasing interest. As the new classification enters common use, further descriptions of related correlations can be anticipated.

Subsolid pulmonary nodules: imaging evaluation and strategic management

PURPOSE OF REVIEW

Given the higher rate of malignancy of subsolid pulmonary nodules and the considerably lower growth rate of ground-glass nodules (GGNs), dedicated standardized guidelines for management of these nodules have been proposed, including long-term low-dose computed tomography (CT) follow-up (≥3 years). Physicians must be familiar with the strategic management of subsolid pulmonary nodules, and should be able to identify imaging features that suggest invasive adenocarcinoma requiring a more aggressive management.

RECENT FINDINGS

Low-dose CT screening studies for early detection of lung cancer have increased our knowledge of pulmonary nodules, and in particular our understanding of the strong although imperfect correlation of the subsolid pulmonary nodules, including pure GGNs and part-solid nodules, with the spectrum of preinvasive to invasive lung adenocarcinoma. Serial CT imaging has shown stepwise progression in a subset of these nodules, characterized by increase in size and density of pure GGNs and development of a solid component, the latter usually indicating invasive adenocarcinoma.

SUMMARY

There is close correlation between the CT features of subsolid nodules (SSNs) and the spectrum of lung adenocarcinoma. Standardized guidelines are suggested for management of SSNs.

Characteristic immunophenotype of solid subtype component in lung adenocarcinoma

BACKGROUND

Lung adenocarcinomas represent a morphologically heterogeneous tumor composed of an admixture of different histologic subtypes (lepidic, papillary, acinar, and solid subtype). The presence of a solid subtype component is reported to be associated with a poorer prognosis. The aim of this study was to evaluate the characteristic immunophenotype of the solid subtype component compared with the immunophenotypes of other components.

METHODS

We analyzed the clinicopathological characteristics of stage I adenocarcinoma patients with predominant solid subtype disease. Furthermore, we immunostained adenocarcinomas with predominant lepidic, papillary, acinar, and solid subtype components (n = 23 each) for 10 molecular markers of tumor invasiveness and scored the results.

RESULTS

Patients showing predominance of the solid subtype component (solid subtype adenocarcinoma) had a poorer prognosis than those showing predominance of the lepidic, papillary, or acinar component. Lymphovascular invasion was more often detected in solid subtype tumors than in others. The solid subtype component showed a significantly stronger staining intensity of laminin-5 expression than the lepidic, papillary, and acinar components (P < 0.001, P < 0.001, and P = 0.016, respectively). The fibronectin and vimentin expression levels were also significantly higher in the solid subtype component than in other components. This immunostaining character was validated by using mixed-subtype adenocarcinomas containing all four components in the same tumor.

CONCLUSIONS

This study concluded that the solid subtype component in lung adenocarcinomas exhibit the invasive immunophenotype, including increased laminin-5 expression, compared with the other components, which may be associated with a poorer prognosis.

Diagnostic workup of lung cancer

Lung cancer is the most frequent cause of mortality worldwide. According to recent estimates, 222,520 new cases of lung cancer (non-small cell and small cell combined) were diagnosed and 157,300 lung cancer-related deaths occurred in 2010 in the United States alone. The two major histologic types of lung cancer are small cell lung cancer and non-small cell lung cancer. The diagnosis and management of lung cancer requires a multidisciplinary approach.

Small peripheral lung adenocarcinoma: CT and histopathologic characteristics and prognostic implications

Since the introduction of computed tomography (CT), detection of small lung cancer, especially small peripheral adenocarcinoma, is common. Recently, the morphological characteristics, including thin-section CT and pathologic findings, and prognosis of small peripheral lung adenocarcinomas have been studied extensively. The radiologic and microscopic findings correlate well with each other and are closely associated with tumour prognosis. Most importantly, some subtypes of small lung adenocarcinomas with specific CT or pathologic features are curable. Therefore, all defining characteristics (CT, pathologic and prognostic) of this kind of tumour should be integrated to improve our understanding, provide guidelines for management and accurately assess its prognosis.

Does lung adenocarcinoma subtype predict patient survival?: A clinicopathologic study based on the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society international multidisciplinary lung adenocarcinoma classification

INTRODUCTION

Lung adenocarcinoma is a heterogeneous group of tumors with a highly variable prognosis, not well predicted by the current pathologic classification system. The 2004 World Health Organization classification results in virtually all tumors encountered in clinical practice being allocated to the adenocarcinoma of mixed subtype category. A new classification developed by an international multidisciplinary expert panel sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society, is based on histomorphologic subtype and has recently been validated in a North American series of 514 stage I lung adenocarcinomas. We investigated the relationship between the new classification and patient survival in a series of Australian patients with stages I, II, and III lung adenocarcinoma.

METHODS

We identified 210 patients from a surgical database who underwent resection of lung adenocarcinoma from 1996 to 2009. Two pathologists, blinded to patient outcome, independently performed histopathologic subtyping according to the new classification. Kaplan-Meier curves were used to calculate 5-year survival for each separate histopathologic subtype/variant. Univariate and multivariate analyses were undertaken to control for validated prognostic factors.

RESULTS

We confirmed that the new subtypes of adenocarcinoma in situ, minimally invasive adenocarcinoma and lepidic-predominant adenocarcinoma had a 5-year survival approaching 100%, whereas micropapillary-predominant and solid with mucin-predominant adenocarcinomas were associated with particularly poor survival. Papillary-predominant and acinar-predominant adenocarcinomas had an intermediate prognosis. This effect persisted after controlling for stage.

CONCLUSIONS

Classification of lung adenocarcinoma according to the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification correlated with 5-year survival. These relationships persisted after controlling for known prognostic patient and tumor characteristics. The new classification has advantages not only for individual patient care but also for better selection and stratification for clinical trials and molecular studies.

High thymidine kinase 1 (TK1) expression is a predictor of poor survival in patients with pT1 of lung adenocarcinoma

In this study, we explore the association of thymidine kinase 1 (TK1) expression in tumour tissues with clinical pathological parameters and prognosis in patients with pathological T1 (pT1) lung adenocarcinoma. The expression of TK1 was studied by immunohistochemistry techniques in 80 patients with surgically resected pT1 lung adenocarcinoma, retrospectively and at >10-year follow-up. Compared to patients with low TK1 expression [labelling index (LI) <25.0%], patients with high TK1 expression (LI ≥ 25.0%) showed significantly increased lymphatic/vascular permeation and lymph node involvement and higher stromal invasion grade and pathological stage, and a greater number of patients had a tumour size of 2.1 to 3.0 cm. The 5-year survival and the mortality during follow-up for patients with high TK1 expression were significantly worse than that of patients with low TK1 expression. The prognoses of the cases with grade 0, grade 1 and grade 2 stromal invasions were similar and were better than those of cases with grade 3. In patients with stromal invasion grade 3, the 5-year survival and the mortality during follow-up were significantly worse for patients with high TK1 compared to patients with low TK1 expression. Univariate analyses showed that stromal invasion and TK1 expression were significant prognostic factors, while in the multivariate analysis, TK1 expression and tumour stage were found to be independent prognostic factors, but not stromal invasion. This is the first study showing that TK1 expression in combination with stromal invasion is a more reliable prognostic factor than stromal invasion classification itself in patients with pT1 lung adenocarcinoma. TK1 expression enables a further classification of the patients and opens opportunities for improved treatment outcome.

Characterization of periostin isoform pattern in non-small cell lung cancer

INTRODUCTION

The extracellular matrix N-glycoprotein periostin (OSF-2, POSTN) is a major constituent of the desmoplastic stroma around solid tumors. It promotes tumor invasion and metastasis via epithelial-mesenchymal transition (EMT). In this study we investigated periostin expression at both RNA and protein level as well as the expression pattern of its splice isoforms in non-small cell lung cancer (NSCLC).

METHODS

Thirty fresh frozen and corresponding formalin-fixed NSCLC tissues (adeno- and squamous cell carcinoma subtype, each n=15) and their matched non-neoplastic tissues were investigated. Periostin mRNA levels were analyzed by quantitative RT-PCR. The EMT-markers periostin and vimentin were analyzed by immunohistochemistry. Laser capture microdissection allowed for analysis of periostin expression in tumor epithelia and stroma, separately. Isoform patterns were investigated by isoform-specific PCR following sequencing in NSCLC, fetal and adult normal lung tissue.

RESULTS

The qRT-PCR analysis showed periostin mRNA up-regulation in NSCLC tissue in relation to normal lung, with significantly higher levels in the adeno-compared to the squamous cell subtype (p<0.05). However, protein levels in both tumor epithelia and stroma correlated with squamous cell carcinoma (p<0.001) and larger tumor size (p<0.05). Further, periostin tumor epithelia expression, correlated with higher tumor grade (p<0.05). Sequence analysis detected eight periostin isoforms in fetal lung, but only five in both NSCLC and matched normal lung tissue. Among the eight isoforms, four are new and were labelled 5, 7, 8 and 9. The exclusive presence of isoforms 1 and 9 in fetal tissue suggests splice-specific regulation during lung embryogenesis. Finally, laser capture microdissection demonstrated that both tumor epithelia and stromal cells can be a source of periostin production in NSCLC.

CONCLUSIONS

This study represents the first analysis of periostin isoform expression patterns in NSCLC and a characterization of periostin expression in cancer versus stromal cells at both RNA and protein level.

Histologic patterns and molecular characteristics of lung adenocarcinoma associated with clinical outcome

BACKGROUND

Lung adenocarcinoma is histologically heterogeneous and has 5 distinct histologic growth patterns: lepidic, acinar, papillary, micropapillary, and solid. To date, there is no consensus regarding the clinical utility of these patterns.

METHODS

The authors performed a detailed semiquantitative assessment of histologic patterns of 240 lung adenocarcinomas and determined the association with patients' clinicopathologic features, including recurrence-free survival (RFS) and overall survival (OS) rates. In a subset of tumors, expression levels of 2 prognostic molecular markers were evaluated: thyroid transcription factor-1 (TTF-1) (n = 218) and a panel of 5 proteins (referred as the FILM signature index) (n = 185).

RESULTS

Four mutually exclusive tumor histology pattern groups were identified: 1) any solid (38%), 2) any papillary but no solid (14%), 3) lepidic and acinar but no solid or papillary (30%), and 4) acinar only (18%). Patients in group 3 had a higher RFS rate than patients in group 1 (hazard ratio [HR], 0.4510; P = .0165) and group 2 (HR, 0.4253; P = .0425). Solid pattern tumors (group 1) were associated with a lower OS rate than nonsolid pattern tumors (all stages: HR; 1.665; P = .0144; stages I and II: HR, 2.157; P = .008). In the patients who had tumors with a nonsolid pattern, high TTF-1 expression was associated significantly with higher RFS (HR, 0.994; P = .0017) and OS (HR, 0.996; P = .0276) rates in all stages, and a high FILM signature index score was associated with lower RFS and OS rates in all stages (RFS: HR, 1.343; P = .0192; OS: HR, 1.371; P = .0156) and in stages I and II (RFS: HR, 1.419; P = .0095; OS: HR, 1.315; P = .0422).

CONCLUSIONS

The presence of a solid histologic pattern was identified as a marker of unfavorable prognosis in patients with primary lung adenocarcinoma. High TTF-1 expression and low FILM signature index scores were associated with a better prognosis for patients who had tumors with a nonsolid pattern.

High expression of stratifin is a universal abnormality during the course of malignant progression of early-stage lung adenocarcinoma

Adenocarcinoma in situ (AIS) of the lung has an extremely favorable prognosis, with a 5-year survival rate of 100%. However, early invasive adenocarcinoma (EIA) often has a fatal outcome. In this study, we compared the expression profiles of AIS with those of EIA showing lymph node metastasis or a fatal outcome, and screened the differentially expressed genes by cDNA microarray. From the genes selected, we focused on Stratifin (SFN, 14-3-3 σ), which showed significantly higher expression in EIA than in AIS. Immunohistochemistry for SFN revealed that more than 95% of EIAs were immunopositive for SFN, in comparison to only 13% of AISs (p <0.05). Interestingly, positivity was detected not only in the invasive region but also in the in situ spreading component of EIA. Functionally, SFN facilitates the cell proliferation capacity of lung adenocarcinoma. These results indicate that SFN overexpression is a universal abnormality during the stepwise progression from in situ to invasive adenocarcinoma of the lung.

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.

Revolution in lung cancer: new challenges for the surgical pathologist

CONTEXT

Traditionally, lung cancer has been viewed as an aggressive, relentlessly progressive disease with few treatment options and poor survival. The traditional role of the pathologist has been primarily to differentiate small cell carcinoma from non-small cell carcinoma on biopsy and cytology specimens and to stage non-small cell carcinomas that underwent resection. In recent years, our concepts of lung cancer have undergone a revolution, including (1) the advent of successful, new, molecular-targeted therapies for lung cancer, many of which are associated with specific histologic cell types and subtypes; (2) new observations on the natural history of lung cancer derived from ongoing high-resolution computed tomography screening studies and recent histologic findings; and (3) proposals to revise the classification of lung cancers, particularly adenocarcinomas, in part because of the first 2 developments.

OBJECTIVE

To summarize the important, new developments in lung cancer, emphasizing the role of the surgical pathologist in personalized care for patients with lung cancer.

DATA SOURCES

Information about the new developments in lung cancer was obtained from the peer-review medical literature and the authors' experiences.

CONCLUSIONS

For decades, we have perceived lung cancer as a relentlessly aggressive and mostly incurable disease for which the surgical pathologist had a limited role. Today, surgical pathologists have an important and expanding role in the diagnosis and treatment of lung cancer, and it is essential to keep informed of new advances.

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.

A grading system of lung adenocarcinomas based on histologic pattern is predictive of disease recurrence in stage I tumors

Currently no objective grading system for pulmonary adenocarcinomas exists. To determine whether specific histologic patterns or combinations thereof could be linked to an objective grading system, the histologic patterns in metastatic tumor deposits was compared with the patterns seen in the corresponding 73 primary tumor to determine whether a specific pattern had higher propensity to metastasize. The concordance of the predominant histologic pattern in the primary tumor and the metastases was of 100% for micropapillary, 86% for solid, 42% for acinar, and 23% for papillary types of adenocarcinoma. Informed by these results, a 3-tier grading system based on the histologic subtypes was established. Grade I, a pattern with low metastatic potential (BAC); Grade II, patterns with intermediate metastatic potential (acinar and papillary); and Grade III, patterns with high metastatic potential (solid and micropapillary). These grades were combined into a number of different scoring systems, whose ability to predict recurrence or death from disease was tested in 366 stage 1 adenocarcinomas. A score based on the 2 most predominant grades was able to stratify patients into low-to-high risk for recurrence or death of disease (P=0.001). The 5-years disease-free survival for patients in the highest score group was of 0.73, compared with 0.84 and 0.92 in the intermediate and lowest score groups. Concordance probability estimate was 0.65 (95% confidence interval 0.57-0.73). Therefore, this scoring system provides valuable information in discriminating patients with different risk of disease-recurrence in a highly homogeneous population of patients with stage I cancer.