Prognostic significance of a histologic subtype in small adenocarcinoma of the lung: the impact of nonbronchioloalveolar carcinoma components

Thin-slice computed tomography enables to classify pulmonary subsolid nodules into pre-invasive lesion/minimally invasive adenocarcinoma and invasive adenocarcinoma: a retrospective study

The aim was to investigate the ability of thin-slice computed tomography (TSCT) to differentiate invasive pulmonary adenocarcinomas (IACs) from pre-invasive/minimally invasive adenocarcinoma (AAH-MIAs), manifesting as subsolid nodules (SSNs) of diameter less than 30 mm. The CT findings of 810 patients with single subsolid nodules diagnosed by pathology of resection specimens were analyzed (atypical adenomatous hyperplasia, n = 13; adenocarcinoma in situ, n = 175; minimally invasive adenocarcinoma, n = 285; and invasive adenocarcinoma, n = 337). According to the classification of lung adenocarcinoma published by WHO classification of thoracic tumors in 2015, TSCT features of 368 pure ground-glass nodules (pGGN) and 442 part-solid nodules (PSNs) were compared AAH-MIAs with IACs. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed. In pGGNs, multivariate analysis of factors found to be significant by univariate analysis revealed that higher mean-CT values (p = 0.006, OR 1.006, 95% CI 1.002-1.010), larger tumor size (p < 0.001, OR 1.483, 95% CI 1.304-1.688) with air bronchogram and non-smooth margins were significantly associated with IACs. The optimal cut-off tumor diameter for AAH-MIAs lesions was less than 10.75 mm (sensitivity, 82.8%; specificity, 80.6%) and optimal cut-off mean-CT value - 629HU (sensitivity, 78.1%; specificity, 50.7%). In PSNs, multivariate analysis of factors found to be significant by univariate analysis revealed that smaller tumor diameter (p < 0.001, OR 0.647, 95% CI 0.481-0.871), smaller size of solid component (p = 0.001, OR 83.175, 95% CI 16.748-413.079),and lower mean-CT value of solid component (p < 0.001, OR 1.009, 95% CI 1.004-1.014) were significantly associated with AAH-MIAs (p < 0.05). The optimal cut-off tumor diameter, size of solid component, and mean-CT value of solid component for AAH-MIAs lesions were less than 14.595 mm (sensitivity, 71.1%; specificity, 83.4%), 4.995 mm (sensitivity, 97.8%; specificity, 92.3%) and - 227HU (sensitivity, 65.6%; specificity, 76.3%), respectively. In subsolid nodules, whether pGGN or PSNs, the characteristics of TSCT can help in distinguishing IACs from AAH-MIAs.

Radiological imaging and pathological findings of small lung adenocarcinoma: a narrative review

The eighth edition of the Lung Cancer Handling Regulations defines the pathological findings of "invasion" in the pathological diagnosis of lung adenocarcinoma and terms it as adenocarcinoma in situ/minimally invasive carcinoma. In addition, the invasion diameter (tumor diameter excluding the lepidic growth region) was adopted as the pT factor, and the classification further reflected prognosis (degree of invasion/progression). Meanwhile, computed tomography imaging-based classification, where the consolidation (nodule) diameter excluding the ground glass shadow area was defined as cT, and the classification reflected the pathological invasion diameter. It is clear that the revision of the eighth edition has reduced discrepancies in the pathological findings of lung adenocarcinoma in CT imaging and assessment of the degree of invasion and progression. At the same time, the 8th edition is not yet accurate enough. Therefore, we will discuss imaging techniques to better predict the extent of adenocarcinoma invasion and progression, based on our own findings and the literature.

Selection of Pathological N0 (pN0) in Clinical IA (cIA) Lung Adenocarcinoma by Imaging Findings of the Main Tumor

OBJECTIVES

We would like to clarify the imaging findings of the main tumor that may omit the requirement for lymph node dissection in clinical IA (cIA) lung adenocarcinoma.

METHODS

A total of 336 patients with cIA lung adenocarcinomas with normal preoperative carcinoembryonic antigen (CEA) who underwent surgical resection were analyzed. We investigated the association between various computed tomography (CT) imaging findings or the maximum standardized uptake value (SUVmax) of fluorodeoxyglucose-position emission tomography (FDG-PET) and lymph node metastasis. The maximum tumor diameter was calculated from the CT images using both the lung window setting (LD) and mediastinal window setting (MD). The diameter of the solid component (CD) was defined as consolidation diameter in lung window setting. The solid component ratio (C/T) was defined as CD/LD.

RESULTS

SUVmax, MD, and C/T were independent factors related to lymph node metastasis, but CD was not (p = 0.38). The conditions required for the positive predictive value (PPV) to reach 100% were 10.6 mm for MD, 12.5 mm for CD, and 0.55 for C/T. SUVmax did not reach 100%.

CONCLUSIONS

In cIA lung adenocarcinoma with CEA in the normal range, we found that it may be possible for lymph node dissection to be omitted by MD, CD, and C/T.

Relationship between stromal cells and tumor spread through air spaces in lung adenocarcinoma

Background

The mechanism underlying tumor spread through air spaces (STAS) has not been well studied. We investigated the role of tumor stromal cells in the pathogenesis of STAS from a pathological perspective and evaluated the prognostic significance of tumor stromal cells and STAS in postoperative patients with lung adenocarcinoma.

Methods

We retrospectively analyzed 208 postsurgical patients with stage I–IIIA lung adenocarcinoma. The presence of STAS was evaluated by hematoxylin and eosin staining. The expression of α‐smooth muscle actin (SMA)‐positive cancer‐associated fibroblasts (CAFs) and CD204‐positive tumor‐associated macrophages (TAMs) was analyzed by immunohistochemistry. A logistic regression model was applied to confirm the predictive factors of STAS. Survival analysis was performed to evaluate the effect of α‐SMA‐positive CAFs, CD204‐positive TAMs, and STAS on prognosis. A nomogram was generated to evaluate the prognosis of postoperative patients.

Results

Logistic regression suggested that the expression of α‐SMA‐positive CAFs (P < 0.001) and the number of CD204‐positive TAMs (P < 0.001) were related to the presence of STAS. The multivariate Cox proportional hazards model suggested that STAS (P = 0.004), α‐SMA‐positive CAFs (P < 0.001), and CD204‐positive TAMs (P < 0.001) were independent risk factors for prognosis. Harrell's c‐indexes for overall and recurrence‐free survival prediction based on nomograms were 0.84 (95% confidence interval 0.76–0.91) and 0.82 (95% confidence interval 0.76–0.89), respectively.

Conclusions

The presence of STAS was associated with high expression of α‐SMA and CD204 in lung adenocarcinoma. Nomograms including STAS and stromal cells as variables are recommended as practical models to evaluate the prognosis of lung adenocarcinoma patients.

Lymph node involvement according to lung adenocarcinoma subtypes: lymph node involvement is influenced by lung adenocarcinoma subtypes

Backgrounds

Invasive adenocarcinoma subtypes are known to be associated with prognosis; however, the underlying reason remains unclear. To find out the reason, we investigated the possible influence of lymph node (LN) involvement by the constituent histologic subtypes in the tumor and clarified the different prognosis according to the predominant histologic subtypes in the tumor and LN.

Methods

A total of 97 consecutive patients who underwent surgical resection for lung invasive adenocarcinoma between February 2009 and December 2015 were included. We analyzed the associations of the histologic subtypes between the tumor and LN and disease-free survival (DFS) according to the histologic subtypes and predicted the histologic subtype in LN involvement using the component ratio of the predominant histologic subtype in the tumor. A P value <0.05 was considered statistically significant.

Results

Acinar and papillary subtypes occupied the majority of the predominant histological subtypes (tumor 73.2%, LN 71.1%). The tumor showed significantly more constituent histologic subtypes than LN (P<0.001). Micropapillary and solid predominant subtype were more common in poorer differentiation (tumor P<0.001, LN P=0.001). The predominant histologic subtype in the tumor was not the same as that in LN and micropapillary and solid predominant subtypes were significantly more prone to LN involvement than other subtypes (P<0.001). Regarding the predominant histologic subtypes in the tumor, there was no significant difference in DFS between micropapillary and solid predominant subtypes and other subtypes. However, regarding the predominant histologic subtypes in LN, micropapillary and solid predominant subtypes had significantly lower DFS than other subtypes (P=0.010). Solid predominant subtype had a significant cutoff value for prediction of the predominant histologic subtype in LN using the component ratio of the predominant histologic subtype in the tumor (cutoff value 12.5%, sensitivity 70.0%, specificity 82.4%, area 0.775, P<0.001).

Conclusions

The present study presented a possible reason of discrepancies in outcomes according to the lung adenocarcinoma constituent subtypes. Micropapillary and solid predominant subtypes had poorer prognosis than other subtypes, which might be explained by being more prone to LN involvement.

Molecular profiling identifies prognostic markers of stage IA lung adenocarcinoma

We previously showed that different pathologic subtypes were associated with different prognostic values in patients with stage IA lung adenocarcinoma (AC). We hypothesize that differential gene expression profiles of different subtypes may be valuable factors for prognosis in stage IA lung adenocarcinoma. We performed microarray gene expression profiling on tumor tissues micro-dissected from patients with acinar and solid predominant subtypes of stage IA lung adenocarcinoma. These patients had undergone a lobectomy and mediastinal lymph node dissection at the Shanghai Chest Hospital, Shanghai, China in 2012. No patient had preoperative treatment. We performed the Gene Set Enrichment Analysis (GSEA) analysis to look for gene expression signatures associated with tumor subtypes. The histologic subtypes of all patients were classified according to the 2015 WHO lung Adenocarcinoma classification. We found that patients with the solid predominant subtype are enriched for genes involved in RNA polymerase activity as well as inactivation of the p53 pathway. Further, we identified a list of genes that may serve as prognostic markers for stage IA lung adenocarcinoma. Validation in the TCGA database shows that these genes are correlated with survival, suggesting that they are novel prognostic factors for stage IA lung adenocarcinoma. In conclusion, we have uncovered novel prognostic factors for stage IA lung adenocarcinoma using gene expression profiling in combination with histopathology subtyping.

Sub-solid Nodule Detection Performance on Reduced-dose Computed Tomography with Iterative Reduction: Comparison Between 20 mA (7 mAs) and 120 mA (42 mAs) Regarding Nodular Size and Characteristics and Association with Size-specific Dose Estimate

RATIONALE AND OBJECTIVES

This study aimed to compare sub-solid nodule detection performances (SSNDP) on chest computed tomography (CT) with Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR 3D) between 7 mAs (0.21 mSv) and 42 mAs (1.28 mSv) in total and in subgroups classified by nodular size, characteristics, and location, and analyze the association of SSNDP with size-specific dose estimate (SSDE).

MATERIALS AND METHODS

As part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases Study, a Japanese multicenter research project, 68 subjects underwent chest CT with 120 kV, 0.35 seconds per rotation, and three tube currents: 240 mA (84 mAs), 120 mA (42 mAs), and 20 mA (7 mAs). The research committee of the study project outlined and approved our study protocols. The institutional review board of each institution approved this study. Axial 2-mm-thick CT images were reconstructed using AIDR 3D. Standard reference was determined by CT images at 84 mAs. Four radiologists recorded SSN presence by continuously distributed rating on CT at 7 mAs and 42 mAs. Receiver operating characteristic analysis was used to evaluate SSNDP at both doses in total and in subgroups classified by nodular longest diameter (LD) (≥5 mm), characteristics (pure and part-solid), and locations (ventral, intermediate, or dorsal; central or peripheral; and upper, middle, or lower). Detection sensitivity was compared among five groups of SSNs classified based on particular SSDE to nodule on CT with AIDR 3D at 7 mAs.

RESULTS

Twenty-two part-solid and 86 pure SSNs were identified. For larger SSNs (LD ≥ 5 mm) as well as subgroups classified by nodular locations and part-solid nodules, SSNDP was similar in both methods (area under the receiver operating characteristics curve: 0.96 ± 0.02 in CT at 7 mAs and 0.97 ± 0.01 in CT at 42 mAs), with acceptable interobserver agreements in five locations. For larger SSNs (LD ≥ 5 mm), on CT at 42 mAs, no significant differences in detection sensitivity were found among the five groups classified by SSDE, whereas on CT with 7 mAs, four groups with SSDE of 0.65 or higher were superior in detection sensitivity to the other group, with SSDE less than 0.65 mGy.

CONCLUSIONS

For SSNs with 5 mm or more in cases with normal range of body habitus, CT at 7 mAs was demonstrated to have comparable SSNDP to CT at 42 mAs regardless of nodular location and characteristics, and SSDE higher than 0.65 mGy is desirable to obtain sufficient SSNDP.

Tumor islands and spread through air spaces: Distinct patterns of invasion in lung adenocarcinoma

Lung adenocarcinoma is a highly heterogeneous disease and the heterogeneity is associated with various patient outcomes even in early-stage tumors. In order to improve prognostic and predictive values, the IASLC/ATS/ERS international multidisciplinary lung adenocarcinoma classification was put forth in 2011 and it has been adopted in the recently published World Health Organization (WHO) classification of Tumours of the Lung, Pleura, Thymus and Heart 4th edition 2015, and lung adenocarcinomas are classified based on the predominant pattern. The performance of the classification in stratifying patient outcomes after resection of Stage I tumors and predicting molecular alterations has been confirmed by several studies. It also includes the category of minimally invasive adenocarcinoma (MIA) that predicts 100% 5-year recurrence free survival after curative resection similar to adenocarcinoma in situ. The diagnosis of MIA is based on not only size of the invasive component but also the absence of aggressive morphologic features such as pleural and/or lymphovascular invasion. Importantly, the WHO 2015 classification has introduced the concept of air space invasion and includes it as the exclusion criteria for MIA. The air space invasion consists of tumor islands and spread through air spaces (STAS). In this review, we will discuss the two entities and their clinical implications.

Prognostic impact of pattern-based grading system by the new IASLC/ATS/ERS classification in Asian patients with stage I lung adenocarcinoma

OBJECTIVES

We examined the prognostic effect of the grading system based on the new IASLC/ATS/ERS classification in an Asian cohort of patients with early-stage lung adenocarcinoma.

MATERIALS AND METHODS

Patients with a lung adenocarcinoma less than 3cm in diameter that had undergone complete anatomic resection, diagnosed with pT1a-2aN0M0 consecutively from 2004 to 2013, were enrolled. All specimens were reviewed according to the new IASLC/ATS/ERS classification. The growth patterns were divided into three major categories: grade 1 for lepidic growth, grade 2 for acinar and papillary patterns, and grade 3 for solid and micropapillary patterns. Each tumor was then graded according to the modified grading system, the final score being the sum of the two most predominant grades. The correlations of clinical and pathological factors with disease-free survival (DFS) and overall survival (OS) were evaluated.

RESULTS

In total, 201 adenocarcinomas were eligible for score grading. Only 37 (18.4%) patients had a pure pathological growth pattern. Higher stage, greater tumor diameter, positive lymphovascular invasion, and a higher score were associated with shorter DFS. In contrast, stage no longer had a significant impact on OS in a multivariable analysis. Acinar/papillary-predominant tumors with a score of 3 or 4 were associated with better survival than those with a score of 5 (5-year DFS rate: 64.68 vs. 44.18%, HR=2.19, 95% CI: 1.24-3.87; 5-year OS rate: 85.61 vs. 68.59%, HR=3.03, 95% CI: 1.25-7.32).

CONCLUSION

The architectural scores may help to stratify survival differences among certain predominant growth subtypes of adenocarcinoma.

Staging of lung cancer

Primary lung cancer is the leading cause of cancer mortality in the world. Thorough clinical staging of patients with lung cancer is important, because therapeutic options and management are to a considerable degree dependent on stage at presentation. Radiologic imaging is an essential component of clinical staging, including chest radiography in some cases, computed tomography, MRI, and PET. Multiplanar imaging modalities allow assessment of features that are important for surgical, oncologic, and radiation therapy planning, including size of the primary tumor, location and relationship to normal anatomic structures in the thorax, and existence of nodal and/or metastatic disease.

Prognostic significance of tumor size of small lung adenocarcinomas evaluated with mediastinal window settings on computed tomography

Background

We aimed to clarify that the size of the lung adenocarcinoma evaluated using mediastinal window on computed tomography is an important and useful modality for predicting invasiveness, lymph node metastasis and prognosis in small adenocarcinoma.

Methods

We evaluated 176 patients with small lung adenocarcinomas (diameter, 1–3 cm) who underwent standard surgical resection. Tumours were examined using computed tomography with thin section conditions (1.25 mm thick on high-resolution computed tomography) with tumour dimensions evaluated under two settings: lung window and mediastinal window. We also determined the patient age, gender, preoperative nodal status, tumour size, tumour disappearance ratio, preoperative serum carcinoembryonic antigen levels and pathological status (lymphatic vessel, vascular vessel or pleural invasion). Recurrence-free survival was used for prognosis.

Results

Lung window, mediastinal window, tumour disappearance ratio and preoperative nodal status were significant predictive factors for recurrence-free survival in univariate analyses. Areas under the receiver operator curves for recurrence were 0.76, 0.73 and 0.65 for mediastinal window, tumour disappearance ratio and lung window, respectively. Lung window, mediastinal window, tumour disappearance ratio, preoperative serum carcinoembryonic antigen levels and preoperative nodal status were significant predictive factors for lymph node metastasis in univariate analyses; areas under the receiver operator curves were 0.61, 0.76, 0.72 and 0.66, for lung window, mediastinal window, tumour disappearance ratio and preoperative serum carcinoembryonic antigen levels, respectively. Lung window, mediastinal window, tumour disappearance ratio, preoperative serum carcinoembryonic antigen levels and preoperative nodal status were significant factors for lymphatic vessel, vascular vessel or pleural invasion in univariate analyses; areas under the receiver operator curves were 0.60, 0.81, 0.81 and 0.65 for lung window, mediastinal window, tumour disappearance ratio and preoperative serum carcinoembryonic antigen levels, respectively.

Conclusions

According to the univariate analyses including a logistic regression and ROCs performed for variables with p-values of <0.05 on univariate analyses, our results suggest that measuring tumour size using mediastinal window on high-resolution computed tomography is a simple and useful preoperative prognosis modality in small adenocarcinoma.

Evidence based imaging strategies for solitary pulmonary nodule

Solitary pulmonary nodule (SPN) is defined as a rounded opacity ≤3 cm in diameter surrounded by lung parenchyma. The majority of smokers who undergo thin-section CT have SPNs, most of which are smaller than 7 mm. In the past, multiple follow-up examinations over a two-year period, including CT follow-up at 3, 6, 12, 18, and 24 months, were recommended when such nodules are detected incidentally. This policy increases radiation burden for the affected population. Nodule features such as shape, edge characteristics, cavitation, and location have not yet been found to be accurate for distinguishing benign from malignant nodules. When SPN is considered to be indeterminate in the initial exam, the risk factor of the patients should be evaluated, which includes patients' age and smoking history. The 2005 Fleischner Society guideline stated that at least 99% of all nodules 4 mm or smaller are benign; when nodule is 5-9 mm in diameter, the best strategy is surveillance. The timing of these control examinations varies according to the nodule size (4-6, or 6-8 mm) and the type of patients, specifically at low or high risk of malignancy concerned. Noncalcified nodules larger than 8 mm diameter bear a substantial risk of malignancy, additional options such as contrast material-enhanced CT, positron emission tomography (PET), percutaneous needle biopsy, and thoracoscopic resection or videoassisted thoracoscopic resection should be considered.

Sublobar resection versus lobectomy in solid-type, clinical stage IA, non-small cell lung cancer

BACKGROUND

Recent studies have demonstrated that sublobar resection is not inferior to lobectomy for peripheral early lung cancer with ground-glass opacification. However, the effect of sublobar resection on solid-type early lung cancer is controversial. The aim of this study was to compare clinical outcomes of patients who have undergone sublobar resection or lobectomy for solid-type, early-stage, non-small cell lung cancer (NSCLC).

METHODS

This study was a retrospective review of the records of patients who underwent lobectomy or sublobar resection between March 2000 and September 2010 for clinical stage IA NSCL. Patients with pure ground-glass opacities or death within 30 days after surgery were excluded. Disease-free interval, survival, and prognostic factors were analyzed.

RESULTS

Thirty-one patients and 133 patients underwent sublobar resection and lobectomy, respectively. There were significant differences in age (P < 0.001), cardiovascular disease (P = 0.001), and diffusing capacity of the lung for carbon monoxide (DLCO) (P < 0.001). The patients with lobectomy had a significantly longer disease-free interval (P < 0.001) and survival (P = 0.001). By multivariate analysis, sublobar resection (P = 0.011), lymphatic vessel invasion (P = 0.006), and number of positive lymph nodes (P = 0.028) were predictors for survival. Sublobar resection (P < 0.001), visceral pleural invasion (P = 0.002), and lymphatic vessel invasion (P < 0.001) were predictors for disease-free interval.

CONCLUSIONS

Lobectomy should remain the standard surgical procedure for solid-type, clinical stage IA, NSCLC.

Why do pathological stage IA lung adenocarcinomas vary from prognosis?: a clinicopathologic study of 176 patients with pathological stage IA lung adenocarcinoma based on the IASLC/ATS/ERS classification

BACKGROUND

Patients with pathological stage IA adenocarcinoma (AC) have a variable prognosis, even if treated in the same way. The postoperative treatment of pathological stage IA patients is also controversial.

METHODS

We identified 176 patients with pathological stage IA AC who had undergone a lobectomy and mediastinal lymph node dissection at the Shanghai Chest Hospital, Shanghai, China, between 2000 and 2006. No patient had preoperative treatment. The histologic subtypes of all patients were classified according to the 2011 International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary lung AC classification. Patients' 5-year overall survival (OS) and 5-year disease-free survival (DFS) were calculated using Kaplan-Meier and Cox regression analyses.

RESULTS

One hundred seventy-six patients with pathological stage IA AC had an 86.6% 5-year OS and 74.6% 5-year DFS. The 10 patients with micropapillary predominant subtype had the lowest 5-year DFS (40.0%).The 12 patients with solid predominant with mucin production subtype had the lowest 5-year OS (66.7%). Univariate and multivariate analysis showed that sex and prognositic groups of the IASLC/ATS/ERS histologic classification were significantly associated with 5-year DFS of pathological stage IA AC.

CONCLUSION

Our study revealed that sex was an independent prognostic factor of pathological stage IA AC. The IASLC/ATS/ERS classification of lung AC identifies histologic categories with prognostic differences that could be helpful in clinical therapy.

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.

Relationship between lung adenocarcinoma histological subtype and patient prognosis

PURPOSE

Lung adenocarcinoma (AC) demonstrates various histological subtypes within the tumour tissue. A panel established jointly by the IASLC, ATS and ERS classified invasive lung ACs based on the predominant histological subtype. We examined the distribution of tumours in lung AC patients according to histological subtype and analysed the effects of this classification on survival.

METHODS

The records of patients who had pulmonary resection for lung cancer between January 2000 and December 2009 were reviewed and 226 lung AC patients who fulfilled the inclusion criteria were identified. Histological subtypes of the ACs and their ratios in the tumour tissue were determined. Tumours were classified according to the predominant histological subtype and subsequently graded. The relationship between the predominant histological subtype, grade and survival were analysed.

RESULTS

Tumours were predominantly acinar in 99 cases (43.8%), solid in 89 (39.3%), lepidic in 20 (8.8%), and papillary in 11 (4.8%), whereas 7 tumours (3%) were variants of AC. Stage significantly affected survival (p = 0.001); however, the predominant histological subtype had no significant effect. The 5-year survival rate for patients with histologically grade II tumours was 48.6%, whereas that in patients with grade III tumours was 56%. (p = 0.69).

CONCLUSION

Invasive lung ACs may be defined by their predominant histological subtype. However, it is not yet possible to conclude that this classification is related to survival.

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.

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.

Number of circulating endothelial progenitor cells and intratumoral microvessel density in non-small cell lung cancer patients: differences in angiogenic status between adenocarcinoma histologic subtypes

INTRODUCTION

Angiogenesis plays a significant role in tumor progression. This study examined the association between the number of circulating endothelial progenitor cells (EPCs), intratumoral microvessel density (MVD) (both of which may be markers for neovascularization), and lung cancer histological types, particularly adenocarcinoma histological subtypes.

METHODS

A total of 83 stage I non-small cell lung cancer (NSCLC) patients underwent complete tumor resection between November 2009 and July 2010. The number of EPCs from the pulmonary artery of the resected lungs was measured by assaying CD34/vascular endothelial growth factor receptor 2 positive cells, and the MVD was assessed immunohistochemically in tumor specimens by staining for CD34.

RESULTS

A statistically significant correlation between the number of EPCs from pulmonary artery and intratumoral MVD was found (p < 0.001). No statistically significant differences in the number of EPCs and the MVD were observed between the adenocarcinomas and the squamous cell carcinomas. Among the adenocarcinoma histological subtypes, a higher number of EPCs and MVD were found significantly more frequently in solid adenocarcinomas than in nonsolid adenocarcinomas (p < 0.001 and p = 0.011, respectively). In addition, solid adenocarcinomas showed higher levels of vascular endothelial growth factor using quantitative real-time polymerase chain reaction in the tumor tissue samples than in the nonsolid adenocarcinomas (p = 0.005).

CONCLUSION

The higher number of circulating EPCs and the MVD of solid adenocarcinoma may indicate the presence of differences in the tumor angiogenic status between early-stage adenocarcinoma histological subtypes. Among adenocarcinoma patients, patients with solid adenocarcinoma may be the best candidates for antiangiogenic therapies.

Advances in Treatment of Lung Cancer With Targeted Therapy

Context.—Ongoing preclinical investigations and clinical trials involving new targeted therapies promise to improve survival for patients with lung cancer. Targeted therapeutic agents, based on genetic mutations and signaling pathways altered in lung cancer, have added significantly to our armamentarium for lung cancer treatment while minimizing drug toxicity. To date, 4 targeted therapies have been approved for treatment of lung cancer by the US Food and Drug Administration: gefitinib in 2002, erlotinib in 2003, bevacizumab in 2006, and crizotinib in 2011.

Objective.—To review targeted therapies in lung cancer, the molecular biomarkers that identify patients likely to benefit from these targeted therapies, the basic molecular biology principles, selected molecular diagnostic techniques, and pathologic features correlated with molecular abnormalities in lung cancer. To review new molecular abnormalities described in lung cancer that are predictive for response to novel promising targeted agents in various phases of clinical trials.

Data Sources.—Review of the literature covering the molecular abnormalities of lung cancer with a focus on the molecular diagnostics and targeted therapy. Special emphasis is placed on summarizing evolving technologies useful in the diagnosis and characterization of lung cancer.

Conclusions.—Molecular testing of lung cancer expands the expertise of the pathologist, who will identify the tumor markers that are predictive of sensitivity or resistance to various targeted therapies and allow patients with cancer to be selected for highly effective and less toxic therapies.

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.

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.

The prognostic impact of cigarette smoking on patients with non-small cell lung cancer

INTRODUCTION

The purposes of this study are to investigate the association between cigarette smoking and clinicopathological characteristics of patients with non-small cell lung cancer (NSCLC) and to evaluate its significance as a predictor of recurrence after resection.

METHODS

A total of 2295 consecutive patients with NSCLC underwent complete resection with systematic node dissection between August 1992 and December 2006 at the National Cancer Center Hospital East.

RESULTS

A statistically significant difference in the 5-year overall survival rate was observed between never and ever smokers in patients with stage I (92% and 76%, respectively, p < 0.001) NSCLC, whereas no difference was observed in stage II (57% and 52%, respectively, p = 0.739) and stage III (30% and 33%, respectively, p = 0.897). In patients with stage I NSCLC, 5-year recurrence-free proportions (RFPs) for never and ever smokers were 89% and 80%, respectively (p < 0.001). In contrast, the 5-year RFPs for never smokers were lower than those for ever smokers in stage II (44% and 60%, respectively, p = 0.049) and stage III (17% and 31%, respectively, p = 0.004). In stage I patients, significant difference in 5-year RFP was observed between never and ever smokers (89% and 83%, respectively) in patients with adenocarcinoma, but not in patients with nonadenocarcinoma (82% and 76%, respectively).

CONCLUSIONS

Smoking history showed different impact on postoperative recurrence in patients with NSCLC between stage I and stages II and III, and depending on histology in stage I patients. Disease stages should be considered while evaluating smoking history as a predictor of recurrence.

How many adenocarcinoma lung cancers come from bronchioloalveolar carcinoma?

BACKGROUND

There is emerging evidence that bronchioloalveolar carcinoma (BAC) is the forerunner of peripheral adenocarcinoma lung cancers (ALC). Since advanced stage ALC is often diagnosed on cytology alone, we hypothesized that the incidence of BAC is underreported and that a large proportion of ALC in our population are part of the BAC-adenocarcinoma sequence.

METHODS

We reviewed the pretreatment computed tomographic (CT) scans of 69 patients with ALC and looked for characteristic features of BAC.

RESULTS

The median patient age was 63, and the majority were of Chinese descent (75.4%). Women comprised 43.5% of the patients (30 patients) and never-smokers comprised 47.8% (33 patients). Only 15 patients (21.7%) had surgical specimens. The presence of BAC components was reported in the pathology of 16 patients (23.2%). CT features classically associated with BAC were found in 35 patients (50.7%). These included air bronchograms or bubble-like lucencies in 24 patients (34.8%), ground-glass opacities in 19 (27.5%), consolidation or pneumonic picture in 11 (15.9%), diffuse small or miliary nodules in 10 (14.5%), and the CT angiogram sign in 4 (5.8%).

CONCLUSIONS

We found provocative radiologic evidence that a large proportion of our ALC cases arise from BAC. The CT findings are consistent with current understanding of the likely pathogenesis of peripheral ALC.

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.

Prognostic impact of histology on early-stage non-small cell lung cancer

BACKGROUND

The purpose of this study is to evaluate the significance of histology as a predictor of recurrence after resection in patients with early-stage non-small cell lung cancer.

METHODS

A total of 1,870 consecutive patients in stage I and II with adenocarcinoma or squamous cell carcinoma (SCC) who underwent complete tumor resection with systematic lymph node dissection between August 1992 and December 2007 were included.

RESULTS

In patients with SCC, significantly more tumors were stage IB or higher. Ever smokers were more common in patients with SCC, and more patients with SCC died of other diseases. In stage IA, a statistically significant difference in the 5-year recurrence-free probability was observed between adenocarcinoma and SCC (91.4% and 82.6%, respectively; P < .001), whereas no such difference was observed in stage IB (74.4% and 73.6%, respectively; P = .934). In stage II, the 5-year recurrence-free probability for adenocarcinoma was significantly lower than that for SCC (47% and 73%, respectively; P < .001). In stage IA, patients with predominantly bronchioloalveolar carcinoma subtype were more common compared with stage IB or higher in patients with adenocarcinoma.

CONCLUSIONS

It is important to offset the prognostic impact of comorbidities associated with cigarette smoking because more patients with SCC died of other diseases. When evaluating its significance as a predictor of recurrence stratified by stage, histology showed a different impact on postoperative recurrence within different substages. Histologic subtype distribution was different among substages in patients with adenocarcinoma. Disease stages should be considered while evaluating histology as a predictor of recurrence.

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.

The morphological diversity of small lung adenocarcinoma with mixed subtypes is associated with local invasiveness and prognosis

OBJECTIVE

Under the current World Health Organization (WHO) classification, 'lung adenocarcinoma with mixed subtypes' is the most frequent type, even in small lung adenocarcinoma, with a diameter of 3 cm or less. For this type of lung adenocarcinoma, it has been reported that the high ratio of the peripheral bronchioloalveolar carcinoma (BAC)/lepidic growth (LG) component was a favorable prognostic factor. On the other hand, the central solid components of lung adenocarcinoma with mixed subtypes have not been focused on in the past. In this study, we took note of the histological features in central solid components of lung adenocarcinoma with mixed subtypes and evaluated whether the morphological diversity of these tumors is associated with local invasiveness and prognostic implication.

METHODS

A total of 103 surgically resected peripheral lung adenocarcinomas were reviewed. All the tumors were 3 cm or less in diameter and histologically diagnosed as lung adenocarcinoma with mixed subtypes, containing a BAC/LG component at the peripheral lesion of the tumor. The tumors were classified into two groups, according to the number of histological subtypes in the tumor, using the modified WHO classification (including the micropapillary subtype); group A (n = 76) has two or three histological subtypes, and group B (n = 27) has four or five subtypes in the tumor, respectively. Then, we evaluated the differences in clinicopathological factors and prognosis between these two groups.

RESULTS

Group B was significantly associated with positive lymphatic and vascular invasion, lymph node metastasis, and advanced pathological stage, compared with group A. The 5-year survival rates of all patients were 91.4% for group A and 43.3% for group B, respectively, with a significant difference (p < 0.01). Multivariate analysis showed that the group classification by the number of histological subtypes was an independent prognostic factor in stage IA patients (p < 0.01).

CONCLUSIONS

The morphological diversity of small lung adenocarcinoma with mixed subtypes is an independent prognostic factor and is associated with tumors' local invasiveness and patients' prognosis.

An automated segmentation approach for highlighting the histological complexity of human lung cancer

Lung cancer nodules, particularly adenocarcinoma, contain a complex intermixing of cellular tissue types: incorporating cancer cells, fibroblastic stromal tissue, and inactive fibrosis. Quantitative proportions and distributions of the various tissue types may be insightful for understanding lung cancer growth, classification, and prognostic factors. However, current methods of histological assessment are qualitative and provide limited opportunity to systematically evaluate the relevance of lung nodule cellular heterogeneity. In this study we present both a manual and an automatic method for segmentation of tissue types in histological sections of resected human lung cancer nodules. A specialized staining approach incorporating immunohistochemistry with a modified Masson's Trichrome counterstain was employed to maximize color contrast in the tissue samples for automated segmentation. The developed, clustering-based, fully automated segmentation approach segments complete lung nodule cross-sectional histology slides in less than 1 min, compared to manual segmentation which requires multiple hours to complete. We found the accuracy of the automated approach to be comparable to that of the manual segmentation with the added advantages of improved time efficiency, removal of susceptibility to human error, and 100% repeatability.

Long-term survival outcomes by smoking status in surgical and nonsurgical patients with non-small cell lung cancer: comparing never smokers and current smokers

BACKGROUND

Survival outcomes of never smokers with non-small cell lung cancer (NSCLC) who undergo surgery are poorly characterized. This investigation compared surgical outcomes of never and current smokers with NSCLC.

METHODS

This investigation was a single-institution retrospective study of never and current smokers with NSCLC from 1975 to 2004. From an analytic cohort of 4,546 patients with NSCLC, we identified 724 never smokers and 3,822 current smokers. Overall, 1,142 patients underwent surgery with curative intent. For survival analysis by smoking status, hazard ratios (HRs) were estimated using Cox proportional hazard modeling and then further adjusted by other covariates.

RESULTS

Never smokers were significantly more likely than current smokers to be women (P < .01), older (P < .01), and to have adenocarcinoma (P < .01) and bronchioloalveolar carcinoma (P < .01). No statistically significant differences existed in stage distribution at presentation for the analytic cohort (P = .35) or for the subgroup undergoing surgery (P = .24). The strongest risk factors of mortality among patients with NSCLC who underwent surgery were advanced stage (adjusted hazard ratio, 3.43; 95% CI, 2.32-5.07; P < .01) and elevated American Society of Anesthesiologists classification (adjusted hazard ratio, 2.18; 95% CI, 1.40-3.40; P < .01). The minor trend toward an elevated risk of death on univariate analysis for current vs never smokers in the surgically treated group (hazard ratio, 1.20; 95% CI, 0.98-1.46; P = .07) was completely eliminated when the model was adjusted for covariates (P = .97).

CONCLUSIONS

Our findings suggest that smoking status at time of lung cancer diagnosis has little impact on the long-term survival of patients with NSCLC, especially after curative surgery. Despite different etiologies between lung cancer in never and current smokers the prognosis is equally dismal.

Mixed Adenocarcinomas of the Lung: Place in New Proposals in Classification, Mandatory for Target Therapy

Context.—Lung cancer is one of the most frequent and lethal malignant neoplasms, but knowledge regarding the molecular basis of its pathogenesis is far from complete due to the striking diversity of different forms. The current lung cancer classification (World Health Organization 2004) can efficiently distinguish clinically relevant major subtypes (small cell and non–small cell carcinomas), but its results are partly inadequate when facing prognostic and therapeutic decisions for non–small cell carcinomas, especially for the group of tumors classified as adenocarcinoma. Lung adenocarcinoma comprises a heterogeneous group of tumors characterized by diverse morphologic features and molecular pathogenesis. The category of mixed adenocarcinomas includes most adenocarcinomas (approximately 80%) and, according to World Health Organization criteria, is defined by the occurrence of a mixed array of different patterns (acinar, papillary, bronchioloalveolar, solid with mucin). The histologic recognition of mixed adenocarcinoma is subjective and cannot consistently discriminate between responders and nonresponders to new targeted therapies (eg, tyrosine kinase inhibitors). Diagnostic problems are mainly related to the poor reproducibility of histologic criteria, especially when applied in small biopsies and cytology, and to the difficulty in assigning each form to a precisely defined entity, as needed by updated therapeutic approaches. In this evolving scenario, pathologists face new challenging diagnostic roles that include not only the precise morphologic definition of carcinoma subtypes but also their molecular characterization.

Objective.—To use a comprehensive critical analysis reconciling the overwhelming variety of biologic, morphologic, molecular, and clinical data to define new classification schemes for lung adenocarcinoma.

Data Sources.—Scientific literature and personal data were used.

Conclusions.—A new classification approach should redefine lung adenocarcinoma heterogeneity reconciling classic morphology, immunophenotypic and molecular features of neoplastic cells, and also relevant information provided by stem cell biology. This approach, which has been already successfully applied in World Health Organization classification of other tumors, could improve the recognition of new reproducible profiles for adenocarcinomas, more closely and reproducibly related to clinical features and response to specific therapies, limiting the use of “wastebasket” categories such as mixed adenocarcinoma.

Update in neoplastic lung diseases and mesothelioma

CONTEXT

Lung cancer is a common disease frequently seen by the surgical pathologist. Although secondary to improvements in screening and radiologic techniques and aggressive resection of small pulmonary nodules, the diagnosis of preneoplastic lesions is increasing in frequency and importance. Consequently, a greater understanding of their role in the development of lung carcinoma is needed for optimal patient care. Two lesions often encountered as small pulmonary nodules are bronchioloalveolar carcinoma and adenocarcinoma, which can be challenging to distinguish. Recently, updates to the TNM classification of non-small cell lung carcinoma have been reported that directly impact prognosis and treatment algorithms. Identification of new molecular targets in pleural mesothelioma and in preneoplastic lesions may lead to improved therapeutic strategies.

OBJECTIVE

To present recent advances in our understanding of neoplastic lung diseases and mesothelioma and to describe how these advances relate to the current practice of pulmonary pathology.

DATA SOURCES

Published literature from PubMed (National Library of Medicine) and primary material from the authors' institution.

CONCLUSIONS

It is important for the surgical pathologist to understand current diagnostic classifications of non-small cell lung cancer and to be aware of the range of preneoplastic lesions, as well as the features useful for distinguishing bronchioloalveolar carcinoma from adenocarcinoma in small pulmonary nodules. Although pleural mesothelioma has distinct features, it can also overlap histologically with adenocarcinoma, and immunohistochemistry can greatly aid in accurate diagnosis. New therapies targeting molecular markers in both non-small cell lung cancer and mesothelioma rely on accurate histopathologic diagnosis of these entities.

Unique clinicopathologic features characterize ALK-rearranged lung adenocarcinoma in the western population

PURPOSE

The anaplastic large cell kinase gene (ALK) is rearranged in approximately 5% of lung adenocarcinomas within the Asian population. We evaluated the incidence and the characteristics of ALK-rearranged lung adenocarcinomas within the western population and the optimal diagnostic modality to detect ALK rearrangements in routine clinical practice.

EXPERIMENTAL DESIGN

We tested 358 lung adenocarcinomas from three institutions for ALK rearrangements by fluorescent in situ hybridization (FISH) and immunohistochemistry with and without tyramide amplification. The clinicopathologic characteristics of tumors with and without ALK rearrangements were compared.

RESULTS

We identified 20 (5.6%) lung adenocarcinomas with ALK rearrangements within our cohort of western patients. ALK rearrangement was associated with younger age (P = 0.0002), never smoking (P < 0.0001), advanced clinical stage (P = 0.0001), and a solid histology with signet-ring cells (P < 0.0001). ALK rearrangement was identified by FISH in 95% of cases and immunohistochemistry with and without tyramide amplification in 80% and 40% of cases, respectively, but neither FISH nor immunohistochemistry alone detected all cases with ALK rearrangement on initial screening. None of the ALK-rearranged tumors harbored coexisting EGFR mutations.

CONCLUSIONS

Lung adenocarcinomas with ALK rearrangements are uncommon in the western population and represent a distinct entity of carcinomas with unique characteristics. For suspected cases, dual diagnostic testing, with FISH and immunohistochemistry, should be considered to accurately identify lung adenocarcinomas with ALK rearrangement.

Subepithelial myofibroblast in lung adenocarcinoma: a histological indicator of excellent prognosis

We report here the presence of subepithelial myofibroblasts in pure bronchioloalveolar carcinoma and a subset of invasive lung adenocarcinoma. The subepithelial myofibroblasts we describe were observed in a peculiar location beneath the cancer cells in the alveolar septa. Immunohistochemically, they were positive for alpha-smooth muscle actin and calponin, but negative for desmin and h-caldesmon. To gain insight into their biological significance, we examined 116 surgically resected lung adenocarcinomas. The resected tumors included 13 bronchioloalveolar carcinomas, 20 mixed type adenocarcinomas with bronchioloalveolar carcinoma components, 57 papillary adenocarcinomas, 22 solid adenocarcinomas with mucin, and 4 acinar adenocarcinomas. All specimens were immunostained for alpha-smooth muscle actin to visualize the myofibroblasts. In all of the pure bronchioloalveolar carcinomas observed, the subepithelial myofibroblasts were completely preserved adjacent to the cancer cells. In mixed adenocarcinomas with bronchioloalveolar carcinoma components, subepithelial myofibroblasts were present in the bronchioloalveolar carcinoma components, but scanty in the invasive areas, where stromal myofibroblasts emerged between the cancer cell nests. Subepithelial myofibroblasts were retained, however, in the invasive areas of a subset of invasive adenocarcinomas. Survival analysis showed that the retention of subepithelial myofibroblasts in these invasive tumors was associated with low rates of lymphatic and vascular invasion, a low rate of lymph node involvement, and an excellent patient survival. These results suggest that subepithelial myofibroblasts increase in bronchioloalveolar carcinomas, but are gradually replaced by typical stromal myofibroblasts during progression into invasive cancer. A subset of invasive adenocarcinomas retains subepithelial myofibroblasts. Analysis of subepithelial myofibroblasts may be helpful in identifying a subset of lung adenocarcinoma with excellent prognosis.

Lung adenocarcinoma as a solitary pulmonary nodule: prognostic determinants of CT, PET, and histopathologic findings

We aimed to retrospectively compare CT, PET, and histopathologic (the extent of bronchioloalveolar carcinoma [BAC] components) findings of solitary pulmonary nodular (SPN) adenocarcinomas of the lung to determine their value as prognostic determinants. We reviewed CT and PET characteristics of tumors and pathologic specimens from 65 consecutive patients who underwent surgical resection for SPN adenocarcinomas. Nodule size and TDR (tumor shadow disappearance rate) were assessed from CT scans, and maximum standardized uptake value (SUVmax) of tumors was measured at PET. On pathologic examination, BAC, non-BAC, and central fibrous scar ratios were quantified. Prognosis was evaluated by noting disease recurrence during a minimum 12-month follow-up period after curative resection. The interrelationships between TDR, SUVmax, BAC, and non-BAC ratio were studied, and relationships between recurrence and various variables were analyzed. The median follow-up time was 33 months, and seven patients (11%) developed disease recurrence after surgical resection. TDR at CT and SUVmax at PET correlated well with pathologic BAC and non-BAC ratios. Between subgroups with and without recurrence, there were significant differences in SUVmax and BAC and non-BAC ratios. Based on univariate survival analyses, pathologic BAC and non-BAC ratios were risk factors significantly related to recurrence, but only high non-BAC ratio remained as an independent factor associated with recurrence in the multivariate analysis (hazard ratio [HR]=0.956, P=0.013). Among the factors examined, pathologic non-BAC ratio is the only independent risk factor for poor prognosis in patients with SPN adenocarcinomas.

Peripheral squamous cell carcinoma of lung: patterns of growth with particular focus on airspace filling

Because the clinical behavior of low-stage adenocarcinomas of the lung is best predicted when adjusted for the presence of a lepidic growth pattern, we studied the marginal growth patterns of 62 peripheral squamous cell carcinomas of lung focusing on the patterns of marginal/peripheral growth and presence of an alveolar filling component. Approximately one fourth of squamous carcinomas had 20% of their gross diameters composed of carcinoma cells filling airspaces with preserved alveolar architecture, and 26% of these cases had their gross size downgraded from a T2 to a T1 lesion. Despite this size recalculation, insufficient numbers of cases made it impossible to determine if this change had independent prognostic significance for T1/T2N0 lesions. Nonetheless, such a growth pattern was common and should be studied further in larger series to determine if an airspace filling growth pattern in squamous carcinoma is clinically important.