Pulmonary adenocarcinoma with a micropapillary pattern: a clinicopathological, immunophenotypic and molecular analysis

Imaging phenotyping using 18F-FDG PET/CT radiomics to predict micropapillary and solid pattern in lung adenocarcinoma

OBJECTIVES

To develop and validate a machine learning model using 18F-FDG PET/CT radiomics signature and clinical features to predict the presence of micropapillary and solid (MP/S) components in lung adenocarcinoma.

METHODS

Eight hundred and forty-six patients who underwent preoperative PET/CT with pathologically confirmed adenocarcinoma were enrolled. After segmentation, 1688 radiomics features were extracted from PET/CT and selected to construct predictive models. Then, we developed a nomogram based on PET/CT radiomics integrated with clinical features. Receiver operating curves, calibration curves, and decision curve analysis (DCA) were performed for diagnostics assessment and test of the developed models for distinguishing patients with MP/S components from the patients without.

RESULTS

PET/CT radiomics-clinical combined model could well distinguish patients with MP/S components from those without MP/S components (AUC = 0.87), which performed better than PET (AUC = 0.829, p < 0.05) or CT (AUC = 0.827, p < 0.05) radiomics models in the training cohort. In test cohorts, radiomics-clinical combined model outperformed the PET radiomics model in test cohort 1 (AUC = 0.859 vs 0.799, p < 0.05) and the CT radiomics model in test cohort 2 (AUC = 0.880 vs 0.829, p < 0.05). Calibration curve indicated good coherence between all model prediction and the actual observation in training and test cohorts. DCA revealed PET/CT radiomics-clinical model exerted the highest clinical benefit.

CONCLUSION

18F-FDG PET/CT radiomics signatures could achieve promising prediction efficiency to identify the presence of MP/S components in adenocarcinoma patients to help the clinician decide on personalized treatment and surveillance strategies. The PET/CT radiomics-clinical combined model performed best. CRITICAL RELEVANCE STATEMENT: 18F-FDG PET/CT radiomics signatures could achieve promising prediction efficiency to identify the presence of micropapillary and solid components in adenocarcinoma patients to help the clinician decide on personalized treatment and surveillance strategies.

Micropapillary and solid components as high-grade patterns in IASLC grading system of lung adenocarcinoma: Clinical implications and management

OBJECTIVES

The grading system proposed by the International Association for the Study of Lung Cancer is based on a combination of predominant histologic subtypes and the proportion of high-grade components with a cutoff of 20%. We aimed to examine the clinical implications of the grading system beyond the discrimination of patient prognosis, while assessing the biological differences among high-grade subtypes.

METHODS

We retrospectively reviewed 648 consecutive patients with resected lung adenocarcinomas and examined their clinicopathologic, genotypic, and immunophenotypic features and treatment outcomes. Besides the differences among grades, the clinical impact of different high-grade components: micropapillary (MIP) and solid (SOL) patterns, was individually evaluated.

RESULTS

Survival outcomes were well-stratified according to the grading system. Grade 3 tumors exhibited aggressive clinicopathologic features, while being an independent prognostic factor in multivariable analysis. A small proportion (<20 %) of high-grade components in grade 2 had a negative prognostic impact. The prognostic difference bordering on the 20 % cutoff of the MIP proportion was validated; however, the proportion of SOL component did not affect prognosis. A survival benefit from adjuvant chemotherapy was observed in grade 3 tumors regardless of histologic subtype, but not in grade 1-2 tumors. The molecular and immunophenotypic features were different among grades, but still heterogeneous in grade 3, with MIP harboring frequent EGFR mutation and SOL exhibiting high PD-L1 expression. The treatment outcome after recurrence was worse in grade 3, but tumors with MIP pattern had an equivalent prognosis to that of grade 1-2 tumors, reflecting the high frequency of molecular targeted therapy.

CONCLUSIONS

In addition to stratifying patient prognosis, the current grading system could discriminate clinical course, therapeutic effects of adjuvant chemotherapy, and molecular and immunophenotypic features. Further stratification based on biological heterogeneity in grade 3 remains necessary to enhance the role of the grading system in guiding patient management.

Identification of Filigree Pattern Increases Diagnostic Accuracy of Micropapillary Pattern on Frozen Section for Lung Adenocarcinoma

INTRODUCTION

The presence of micropapillary (MIP) in early-stage lung adenocarcinoma was associated with a poorer prognosis, especially in patients undergoing sublobectomy. However, data on the sensitivity of frozen section (FS) evaluation of MIP was still limited. We included the concept of filigree pattern on FS to assess its effect on the diagnostic sensitivity and specificity of MIP, and verify its prognostic value in stage T1 lung adenocarcinoma.

METHODS

A panel of five pathologists evaluated 125 patients with T1 lung adenocarcinoma from January to February 2014 as a study cohort, and 151 patients from January to February 2020 as a validation cohort. The diagnostic accuracy of filigree and classical micropapillary (cMIP) pattern on FS was investigated.

RESULTS

Diagnostic sensitivity of MIP pattern on FS increased from 43.2% to 65.3% and 56.8% to 81.1% in the study cohort and validation cohort, and both with good specificity. Filigree not only increased the sensitivity of identifying MIP when absence of cMIP, but also increased the sensitivity when presence of minor amount of cMIP. The almost perfect agreement among five pathologists was reached on cMIP and substantial agreement was reached on the filigree in the two cohorts. Moreover, the cMIP and filigree were both correlated with poorer recurrence-free survival (p_cMIP = 0.003; p_filigree = 0.032) and overall survival (p_cMIP = 0.004; p_filigree = 0.005).

CONCLUSION

Identification of filigree may improve the diagnostic sensitivity of MIP pattern on FS. FS was feasible for the detection of filigree and cMIP patterns in stage T1 lung adenocarcinomas.

Enhanced CT-Based Radiomics to Predict Micropapillary Pattern Within Lung Invasive Adenocarcinoma

Objective

We aimed to investigate whether enhanced CT-based radiomics can predict micropapillary pattern (MPP) of lung invasive adenocarcinoma (IAC) in the pre-op phase and to develop an individual diagnostic predictive model for MPP in IAC.

Methods

170 patients who underwent complete resection for pathologically confirmed lung IAC were included in our study. Of these 121 were used as a training cohort and the other 49 as a test cohort. Clinical features and enhanced CT images were collected and assessed. Quantitative CT analysis was performed based on feature types including first order, shape, gray-level co-occurrence matrix-based, gray-level size zone matrix-based, gray-level run length matrix-based, gray-level dependence matrix-based, neighboring gray tone difference matrix-based features and transform types including Log, wavelet and local binary pattern. Receiver operating characteristic (ROC) and area under the curve (AUC) were used to value the ability to identify the lung IAC with MPP using these characteristics.

Results

Using quantitative CT analysis, one thousand three hundred and seventeen radiomics features were deciphered from R (https://www.r-project.org/). Then these radiomic features were decreased to 14 features after dimension reduction using the least absolute shrinkage and selection operator (LASSO) method in R. After correlation analysis, 5 key features were obtained and used as signatures for predicting MPP within IAC. The individualized prediction model which included age, smoking, family tumor history and radiomics signature had better identification (AUC=0.739) in comparison with the model consisting only of radiomics features (AUC=0.722). DeLong test showed that the difference in AUC between the two models was statistically significant (P<0.01). Compared with the simple radiomics model, the more comprehensive individual prediction model has better prediction performance.

Conclusion

The use of radiomics approach is of great value in the diagnosis of tumors by non-invasive means. The individualized prediction model in the study, when incorporated with age, smoking and radiomics signature, had effective predictive performance of lung IAC with MPP lesions. The combination of imaging features and clinical features can provide additional diagnostic value to identify the micropapillary pattern in IAC and can affect clinical diagnosis and treatment.

Novel genetic characteristics in low-grade fetal adenocarcinoma of the lung

Background

Low‐grade fetal adenocarcinoma of the lung (L‐FLAC) is a rare subtype of lung adenocarcinoma with undetermined histological features and genetic abnormalities. In this study, we attempted to investigate the pathological characteristics and genomic profiles of L‐FLAC.

Methods

Among 9839 cases of primary lung adenocarcinoma resected at Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College between January 2011 and June 2016, three cases diagnosed with L‐FLAC were selected. An immunohistochemical profile and whole exome sequencing (WES) using tumor and normal tissues was conducted. The last follow‐up date of patients was January 2021.

Results

Three cases diagnosed with L‐FLAC were finally screened, suggesting a percentage of 0.03%. All three patients were male and diagnosed as stage I following radical lobectomy. The missense variant was found to be the major gene mutation type using WES. CTNNB1 and DICER1 were the two most frequent gene mutations. All cases demonstrated positive TTF‐1 expression. In addition, two patients showed positive expression of β‐catenin (nuclear/cytoplasmic expression), CgA and Sny. Negative expression of PD‐L1 in tumor cells was observed in all three cases. One case with a relatively high tumor mutation burden (TMB) (2.18 mut/Mb) had an inferior overall survival of 11.5 months. However, the other two cases with a lower TMB (0.12 and 0.74 mut/Mb) still acquired disease‐free status up to the last follow‐up date.

Conclusions

L‐FLAC has a specific molecular background which is different from lung adenocarcinoma. Furthermore, gene heterogeneity was found and might be the reason for a dramatically different prognosis in these L‐FLAC patients.

High-grade fetal adenocarcinoma of the lung with abnormal expression of alpha-fetoprotein in a female patient: Case report

INTRODUCTION

Fetal adenocarcinoma of the lung (FLAC) is an extremely rare tumor. Due to its rarity, most of the knowledge about FLAC comes from case reports. FLAC is an invasive adenocarcinoma that is similar to the fetal lung in the pseudo-glandular stage (8-16 weeks of gestation). Owing to the differences in histopathology and clinical process, FLAC has been further divided into low-level (L-FLAC) and high-level (H-FLAC). H-FLAC is usually associated with other conventional types of lung adenocarcinoma. Lung adenocarcinoma that produces alpha-fetoprotein (AFP) is a rare type of lung cancer. Its characteristics have not been fully elucidated.

PATIENTS CONCERNS

We recently encountered this type of FLAC in a 51-year-old female patient. A computed tomography (CT) scan of the chest revealed a 74 × 51-mm sized tumor in the lingual segment of the superior lobe of the left lung. Among the tumor markers, serum AFP was elevated (816.2 ng/mL).

PRIMARY DIAGNOSIS, INTERVENTIONS, AND OUTCOMES

The diagnosis of FLAC in this patient was confirmed by bronchoscopy with lung biopsy. Through a thoracoscope, left lung pneumonectomy, and mediastinal lymph node dissection were performed. The postoperative pathological results were consistent with the preoperative diagnosis of H-FLAC. Western blotting showed the difference in the AFP expression between the normal lung tissue and the cancerous lung tissue. Eventually, the diagnosis was AFP-producing H-FLAC. Using an immunohistochemical marker for AFP, cancer cells were shown to express AFP, specifically in their nuclei. After the operation, the patient underwent conventional chemotherapy. Her serum AFP gradually decreased over the course of 2 weeks.

CONCLUSION

Presently, specific tumor markers for the diagnosis of lung cancer have not been established. To the best of our knowledge, this is the first case of abnormal AFP expression in a patient with H-FLAC. It may provide a basis for the clinical diagnosis of H-FLAC, a rare tumor, and AFP may be considered as a specific tumor marker.

Clinical implication of minimal presence of solid or micropapillary subtype in early-stage lung adenocarcinoma

BACKGROUND

We investigated the clinical features and surgical outcomes of lung adenocarcinoma with minimal solid or micropapillary (S/MP) components, with a focus on stage IA.

METHODS

We enrolled 506 patients with lung adenocarcinoma who underwent curative resection in this study. Clinical features and surgical outcomes were compared between the groups with and without the S/MP subtype (S/MP+ and S/MP-, respectively), and between the group with an S/MP proportion of ≤5% (S/MP5) and the S/MP-.

RESULTS

The S/MP subtype was present in 247 patients (48.8%); 129 (25.5%) were grouped as the S/MP5 group. The S/MP+ and S/MP5 groups had larger tumors, higher frequency of lymph node metastasis, and more advanced stages of disease than the S/MP- group (P < 0.001, all comparisons). Pleural, lymphatic, and vascular invasions occurred more frequently in the S/MP+ and S/MP5 groups (P < 0.001, all comparisons for S/MP+ vs. S/MP-; P ≤ 0.01, all comparisons for S/MP5 vs. S/MP-). The S/MP+ and S/MP5 groups showed a shorter time to recurrence and cancer-related death than the S/MP- group(P < 0.001, both comparisons). For stage I, the presence or absence of the S/MP subtype defined prognostic subgroups better than the stage IA/IB classification. Notably, in the multivariate analysis, the minimal S/MP component was a significant predictor of recurrence, even in stage IA.

CONCLUSIONS

The presence of the minimal S/MP component was a significant predictor of poor prognosis after surgery, even in stage IA patients. Clinical trials to evaluate the advantages of adjuvant chemotherapy for this subset of patients and further investigations to understand underlying biological mechanisms of poor prognosis are needed.

KEY POINTS

Significant findings of the study: We demonstrated that only minimal presence of solid or micropapillary component was profoundly associated with aggressive clinicopathological features and poor prognosis after complete resection even in stage IA lung adenocarcinoma.

WHAT THIS STUDY ADDS

Our results suggest that minimal presence of these subtypes is a strong prognostic factor which should be taken into account in the risk assessment for adjuvant chemotherapy in lung adenocarcinoma.

Comprehensive review of fetal adenocarcinoma of the lung

Fetal adenocarcinoma of the lung (FLAC) is a rare tumor. It accounts for ~0.1%-0.5% of all pulmonary neoplasms. Due to its rarity, much of the world literature regarding FLAC comes from case reports and case series. FLAC is an adenocarcinoma resembling developing fetal lung in its pseudoglandular stage (8-16 weeks of gestation). It is distinguishable from pulmonary blastoma (PB) because it lacks the mesenchymal component which is a hallmark finding in PB. Due to differences in histopathology and clinical course, FLAC has been further categorized into low-grade (L-FLAC) and high-grade (H-FLAC) forms. L-FLAC displays low nuclear atypia and prominent morule formation and has a pure pattern. H-FLAC typically presents with at least 50% fetal morphology, and is often associated with other conventional types of lung adenocarcinoma. FLAC expresses neuroendocrine markers and thyroid transcription factor 1 in most cases. L-FLAC has an aberrant nuclear/cytoplasmic expression of β-catenin and presents mutations in this gene. H-FLAC overexpresses p53. These tumors have a very low frequency of mutations in KRAS and EGFR; it is thought that they are different from a molecular point of view to conventional lung adenocarcinomas. Approximately 25%-40% of patients are asymptomatic at presentation; most of them are incidental findings on chest radiographs. H-FLAC is more common in elderly male patients, with a heavy smoking history. L-FLAC tends to occur in young females. Patients with L-FLAC are usually diagnosed with stage I-II disease, while patients with H-FLAC usually present with a more advanced-stage disease. Poor prognostic factors for FLAC are thoracic lymphadenopathy, metastases at diagnosis, and tumor recurrence; however, the 10-year survival for FLAC is estimated at 75%.

The more the micropapillary pattern in stage I lung adenocarcinoma, the worse the prognosis-a retrospective study on digitalized slides

Although the majority of lung adenocarcinomas show mixed pattern, only the predominant component is taken into account according to the novel classification. We evaluated the proportion of different patterns and their impact on overall survival (OS) and disease-free survival (DFS). Patterns were recorded according to predominance and their proportions were rated and calculated by objective area measuring on digitalized, annotated slides of resected stage I lung adenocarcinomas. Spearman's rank correlation, Kaplan-Meier models and the log rank test were used for statistical evaluation. Two hundred forty-three stage I adenocarcinoma were included. Lepidic pattern is more frequent in tumours without recurrence (20 vs. 8%), and lepidic predominant tumours have favourable prognosis (OS 90.5%, DFS 89.4%), but proportions above 25% are not associated with improving outcome. Solid and micropapillary patterns are more frequent in patients with recurrence (48 vs. 5% and 13 vs. 4%) and predominance of each one is associated with unfavourable prognosis (OS 64.1%, DFS 56.3% and OS 28.1%, DFS 28.1%, respectively). Above 25%, a growing proportion of solid or micropapillary pattern is not associated with worsening prognosis. In contrast, tumours having micropapillary pattern as secondly predominant form a different intermediate group (OS 51.1%, DFS 57.8%). Our study was based on measured area of each growth pattern on all available slides digitalized. This is the most precise way of determining the size of each component from the material available. We propose using predominant and secondly predominant patterns for prognostic purposes, particularly in tumours having solid or micropapillary patterns.

Prognostic factors in curatively resected pathological stage I lung adenocarcinoma

Background

Patients with pathological stage I (p I) lung adenocarcinoma show variabilities in prognosis even after complete resection. The factors resulting in heterogeneities of prognosis remain controversy. The aim of this study was to identify the risk factors affecting recurrence/metastasis and survival in patients with curatively resected p I lung adenocarcinoma.

Methods

A total of 252 patients with p I lung adenocarcinoma underwent curative resection between January 1st, 2009 to September 30th, 2011 were retrospectively reviewed to analyze the associations of recurrence and survival with the following clinicopathological variables: gender, age, cigarette smoking, family cancer history, tumor size, TNM stage, tumor differentiation, visceral pleural invasion, bronchial involvement, lymphovascular invasion, postoperative adjuvant treatment, pathological subtypes and micropapillary pattern.

Results

Among those 252 patients, 48 had local recurrence or distant metastasis, the rest 204 patients had no relapse until the last follow-up. Cox univariate survival analysis revealed that tumor size (P<0.001), TNM stage [disease-free survival (DFS), P<0.001; overall survival (OS), P=0.004], tumor differentiation (P<0.001), bronchial involvement (P<0.001), lymphovascular invasion (DFS, P=0.021; OS, P=0.001) and micropapillary pattern (DFS, P<0.001; OS, P=0.003) were significantly associated with DFS and OS, while cigarette smoking (P=0.029) and pathological subtypes (P=0.041) were found to be risk factors for DFS either. In multivariate analysis, tumor differentiation (P<0.001) was an independent risk factor for both DFS and OS, TNM stage (P=0.007), bronchial involvement (P=0.004) and micropapillary pattern (P=0.001) only for DFS, while tumor size (P=0.009) and lymphovascular invasion (P=0.010) were found to be independent risk factors only for OS.

Conclusions

Tumor size, TNM stage, tumor differentiation, bronchial involvement, lymphovascular invasion and micropapillary pattern could be considered as risk factors for predicting local recurrence or distant metastasis and survival in curatively resected p I lung adenocarcinoma patients.

EGFR, KRAS, and BRAF mutational profiles of female patients with micropapillary predominant invasive lung adenocarcinoma

Background/aim: This study aimed to analyze EGFR, KRAS, and BRAF mutations in females with micropapillary predominant invasive lung adenocarcinoma and their relationships with immunohistochemical and clinicopathological patterns.Materials and methods: A total of 15 females with micropapillary lung adenocarcinoma were selected. Mutational analysis of the EGFR, KRAS, and BRAF genes was carried out. Information regarding the demographic data, tumor size, treatment, and survival time for each patient was collated, and the predominant cell type, secondary architectural growth patterns, psammoma bodies, necrosis, and visceral pleural and angiolymphatic invasions were evaluated.Results: We identified EGFR mutation in six cases, KRAS mutation in three cases, and BRAF mutation in one case. EGFR, c-kit, VEGFR, and bcl-2 positivity was observed in ten, seven, four, and six cases, respectively. All cases were positive for VEGF (strong positivity in 11 cases and weak positivity in four cases) and bcl-2 (strong positivity in nine cases and weak positivity in six cases). Seven (46.6%) cases were positive for c-kit and 10 (66.6%) cases were positive for EGFR. Conclusion: EGFR mutation occurred at a higher incidence rate in micropapillary predominant invasive adenocarcinoma than has previously been found in conventional lung adenocarcinomas. KRAS mutation was observed as having a similar frequency to what was previously observed, but the frequency of BRAF mutation was lower than previously reported.

Protein overexpression and gene amplification of cellular mesenchymal-epithelial transition factor is associated with poor prognosis in micropapillary-predominant subtype pulmonary adenocarcinoma

Micropapillary-predominant subtype pulmonary adenocarcinoma (MPPAC) is a subtype of lung cancer with poor prognosis. Cellular mesenchymal-epithelial transition factor (c-MET) is a promising pharmaceutic target found to be associated with the survival of patients with pulmonary adenocarcinoma. In this study, we aimed to analyze c-MET protein overexpression and gene amplification in MPPAC samples and to elucidate their relationship with the clinicopathological characteristics of the patients. c-MET protein expression was examined by immunohistochemical analyses, and gene amplification was detected by fluorescence in situ hybridization. A total of 86 MPPAC cases were included in this study. The prevalence of c-MET protein overexpression and gene amplification were 62.8% and 10.5%, respectively. C-MET protein overexpression was significantly associated with smoking status, lymphatic and venous invasion, and tumor-node-metastasis stage (P = .014, P = .040, and P = .004, respectively), but c-MET gene amplification showed no relation with any of these characteristics. Univariate analysis revealed that pleural invasion, lymph node metastasis, lymphatic and venous invasion, tumor-node-metastasis stage, c-MET protein overexpression, and c-MET gene amplification were associated with poor prognosis (P = .041, P < .001, P = .001, P < .001, P = .001 and P = .001, respectively), but only c-MET gene amplification was an independent prognostic marker (P = .04). These results indicated that c-MET is an important biomarker. Also, c-MET protein overexpression and gene amplification are highly related to poor prognosis in patients with MPPAC.

Sublobar Resection Margin Width Does Not Affect Recurrence of Clinical N0 Non-small Cell Lung Cancer Presenting as GGO-Predominant Nodule of 3 cm or Less

BACKGROUND

Sublobar resection of lung cancer may benefit patients with lung cancer presenting as ground-glass opacity (GGO) nodules. The purpose of this study was to evaluate the effect of margin width on recurrence after sublobar resection in patients with clinical N0 non-small cell lung cancer presenting as GGO-predominant nodule.

METHODS

We conducted a retrospective chart review of 91 patients treated for clinical N0 non-small cell lung cancer ≤3 cm by sublobar resection with clear resection margins. We assigned them to two groups: GGO-predominant tumor and solid-predominant tumor. Each group was subdivided into two groups according to the margin width: resection margin ≤5 mm and resection margin >5 mm. We analyzed the clinicopathological findings and survival among these four groups.

RESULTS

There was no recurrence in GGO-predominant tumors after sublobar resection. Margin width did not influence the recurrence in GGO-predominant tumors. In the cases of solid-predominant tumor, 5-year recurrence-free survival after sublobar resection according to margin width ≤5 and >5 mm was 24.2 and 79.6 %, respectively (p < 0.001). Therefore, narrow margin width (resection margin ≤5 mm) was a significant risk factor for recurrence of solid-predominant tumors (hazard ratio 3.868, 95 % confidence interval 1.177-12.714, p = 0.026).

CONCLUSIONS

The width between the tumor and resection margin does not affect the recurrence after R0 sublobar resection in patients with clinical N0 GGO-predominant lung cancer ≤3 cm. By contrast, margin width is a significant risk factor for recurrence after sublobar resection in patients with clinical N0 solid-predominant lung cancer.

Differences between low and high grade fetal adenocarcinoma of the lung: a clinicopathological and molecular study

BACKGROUND

Fetal adenocarcinoma of the lung (FLAC) is a rare entity of lung cancer. It is classified into low-grade fetal adenocarcinoma (L-FLAC) and high-grade fetal adenocarcinoma (H-FLAC). We aim to report the clinicopathological and molecular features of FLAC in Chinese patients.

METHODS

FLACs were screened from a consecutive lung adenocarcinoma series comprising 920 cases. The clinicopathological features L-FLAC and H-FLAC were retrospectively reviewed via immunohistochemical study and mutation analysis.

RESULTS

Three L-FLAC and five H-FLAC cases were identified. L-FLAC mainly occurred in young patients and was predominantly in stage I upon diagnosis and conferred favorable outcomes. L-FLAC tumors were characterized by the glycogen-rich columnar cells lining the complex glandular structures, with low nuclear atypia, morule formation, and mainly nuclear- and cytoplasmic-localized β-catenin expression. In contrast, H-FLAC predominantly occurred in elderly men with a history of smoking. The stage of H-FLAC was often advanced at presentation and had a poor prognosis. H-FLAC tumors exhibited more prominent atypia of the nucleus, the absence of morule formation, and largely membrane-localized β-catenin. All 5 H-FLACs were immunohistochemically characterized by overexpression of the p53 protein; the L-FLAC tumors were negative for p53. Two cases of H-FLAC were positive for AFP. No Her-2 or ALK-D5F3 overexpression was observed in any of the tumors. EGFR L858R point mutation was identified in one of the H-FLAC cases. EGFR T790M mutation was detected in one of the L-FLAC cases. No mutations in KRAS, PIK3CA or BRAF were detected.

CONCLUSIONS

L-FLAC and H-FLAC exhibited distinctive clinicopathological, immunophenotypic and molecular features with potential prognostic value.

Imaging Phenotyping Using Radiomics to Predict Micropapillary Pattern within Lung Adenocarcinoma

INTRODUCTION

Lung adenocarcinomas (ADCs) with a micropapillary pattern have been reported to have a poor prognosis. However, few studies have reported on the imaging-based identification of a micropapillary component, and all of them have been subjective studies dealing with qualitative computed tomography variables. We aimed to explore imaging phenotyping using a radiomics approach for predicting a micropapillary pattern within lung ADC.

METHODS

We enrolled 339 patients who underwent complete resection for lung ADC. Histologic subtypes and grades of the ADC were classified. The amount of micropapillary component was determined. Clinical features and conventional imaging variables such as tumor disappearance rate and maximum standardized uptake value on positron emission tomography were assessed. Quantitative computed tomography analysis was performed on the basis of histogram, size and shape, Gray level co-occurrence matrix-based features, and intensity variance and size zone variance-based features.

RESULTS

Higher tumor stage (OR = 3.270, 95% confidence interval [CI]: 1.483-7.212), intermediate grade (OR = 2.977, 95% CI: 1.066-8.316), lower value of the minimum of the whole pixel value (OR = 0.725, 95% CI: 0.527-0.98800), and lower value of the variance of the positive pixel value (OR = 0.961, 95% CI: 0.927-0.997) were identified as being predictive of a micropapillary component within lung ADC. On the other hand, maximum standardized uptake value and tumor disappearance rate were not significantly different in groups with a micropapillary pattern constituting at least 5% or less than 5% of the entire tumor.

CONCLUSION

A radiomics approach can be used to interrogate an entire tumor in a noninvasive manner. Combining imaging parameters with clinical features can provide added diagnostic value to identify the presence of a micropapillary component and thus, can influence proper treatment planning.

Clinicopathologic Factors Associated With Occult Lymph Node Metastasis in Patients With Clinically Diagnosed N0 Lung Adenocarcinoma

BACKGROUND

In some patients, clinical N0 (cN0) lung adenocarcinoma diagnosed by preoperative computed tomography scanning and positron emission tomography scanning was staged as pathologic N1 (pN1) or N2 (pN2) postoperatively. The aim of this study was to determine the preoperative and postoperative clinicopathologic factors related to nodal upstaging after a surgical operation.

METHODS

We conducted a retrospective chart review of 350 patients treated for cN0 lung adenocarcinoma by curative resection. We analyzed clinicopathologic findings, comparing pN0 patients with the nodal upstaging group.

RESULTS

Of 350 patients treated for cN0 tumors, 305 (87.1%) were confirmed postoperatively as having pN0 tumors, and 45 (12.9%) were confirmed as having pN1 or pN2 tumors. The mean maximum standardized uptake value (SUVmax) was higher in the nodal upstaging group than in the pN0 group (6.9 versus 3.8, p = 0.004); the upstaging group also included more cases in which SUVmax was greater than 5 (70.5% versus 24.8%, p < 0.001). Pleural invasion, lymphatic invasion, and vascular invasion were all more frequently seen in the nodal upstaging group than in the pN0 group (all p < 0.001). The presence of tumors with a micropapillary component was higher in the nodal upstaging group (p < 0.001). Multivariate logistic regression analysis identified SUVmax greater than 5, lymphatic invasion, vascular invasion, and a micropapillary component as significant risk factors for nodal upstaging.

CONCLUSIONS

In lung adenocarcinoma diagnosed as clinical N0 by chest computed tomography and positron emission tomography scanning, the possibility of occult lymph node metastasis increases with SUVmax greater than 5 and when lymphatic invasion, vascular invasion, and a micropapillary component are present.

Clinicopathologic correlates of postoperative N1 or N2 nodal upstaging in non-small cell lung cancer

BACKGROUND

Clinical and pathologic determinations of lymph node staging are critical in the treatment of lung cancer. However, up- or downstaging of nodal status frequently is necessitated by postsurgical findings. This study was conducted to evaluate clinicopathologic features that impact nodal upstaging in patients staged primarily via positron emission tomography/computed tomography (PET/CT) and chest CT prior to surgery.

METHODS

Between years 2011 and 2014, 634 patients underwent surgical treatment for non-small cell lung cancer (NSCLC) at our institution. Excluding 37 patients (given induction chemotherapy), 103 patients pathologically staged as N1 or N2 NSCLC. Nodal upstaging patients were classified into group A and non-upstaging patients into group B. We compared clinical characteristics and pathological results of group A with group B.

RESULTS

Ultimately, 59 patients (57.3%) were assigned to group A and 44 patients (42.7%) to group B. Patients in group A (vs. group B) were significantly younger (61.6 vs. 68.4 years; P<0.001) and more often were female (47.5% vs. 15.9%; P=0.001), with shorter smoking histories (12.2 vs. 28.8 pack years; P<0.001) and lower maximum standardized uptake values (SUVmax) (7.3 vs. 10.4; P=0.001). Most upstaged (group A) tumors (50/59, 84.7%) were adenocarcinomas, displaying micropapillary (MPC; n=36) and lepidic (n=35) component positivity with significantly greater frequency (both, P<0.001); and the frequency of epidermal growth factor receptor (EGFR) mutation (n=36) was significantly greater in this subset (P=0.001). Multivariate analysis (logistic regression) indicated a significant correlation between MPC positivity and nodal upstaging (P=0.013).

CONCLUSIONS

In patients upstaged postoperatively to N1 or N2 stage of NSCLC, occult lymph node metastasis and MPC positivity were significantly related.

Differing histopathology and prognosis in pulmonary adenocarcinoma at central and peripheral locations

BACKGROUND

Pulmonary adenocarcinoma is largely peripheral in location but often does occur centrally. In the course of this study, clinicopathologic features of pulmonary adenocarcinoma, including the prognosis of early-stage disease, were assessed and compared by tumor location.

METHODS

A retrospective chart review was conducted, examining 308 patients treated for pulmonary adenocarcinoma by curative resection. Clinicopathologic findings were analyzed, comparing central and peripheral primary locations. Recurrence-free survival (RFS) rates were determined for tumor subsets (central vs. peripheral).

RESULTS

At all disease stages (N=308), 41 patients (13.3%) with central adenocarcinoma were documented. In central (vs. peripheral) adenocarcinoma, mean tumor size was larger (3.1 vs. 2.3 cm, P=0.014), nodal metastasis was more frequent (P=0.012), and the likelihood of advanced disease (stages II and III) was greater (P=0.007). Microscopically, central adenocarcinoma displayed more acinar (53.3% vs. 38.9%; P=0.006) and less lepidic (20.9% vs. 37.5%; P=0.001) growth. At stage I disease [N=329; central, 25 (10.5%)], group similarities were sustained. As with disease overall, central adenocarcinoma contained more acinar (51.8% vs. 37.1%; P=0.025) and fewer lepidic (26.2% vs. 44.1%; P=0.006) areas. Three-year RFS rates for central and peripheral adenocarcinoma at all disease stages were 63.2% and 82.5% (P=0.024), respectively, compared with 70.4% and 91.0% (P=0.023), respectively at stage I. Lepidic growth was identified as a statistically significant risk factor for early recurrence by multivariate analysis.

CONCLUSIONS

Central pulmonary adenocarcinoma is generally detected at an advanced stage. In early (stage I) disease, the prognosis is comparatively worse for central adenocarcinoma, owing to significant micromorphologic differences in central and peripheral tumors.

The importance of the lepidic component as a prognostic factor in stage I pulmonary adenocarcinoma

Background

Stage I pulmonary adenocarcinoma (PA) can offer an unfavorable prognosis. The aim of this study was to classify the prognosis of stage I PA on the basis of the lepidic component and to confirm whether the lepidic component can be used as a criterion for predicting the prognosis of stage I PA.

Methods

We conducted a retrospective study of patients who underwent curative surgery for stage I and IIA PA. Stage I disease was divided into three groups on the basis of the lepidic component: group 1, ≤10 %; group 2, >10 to 50 %; and group 3, >50 %. We compared recurrence-free survival (RFS) rates among groups 1, 2, and 3, and stage IIA disease. We also evaluated risk factors for disease recurrence with multivariate analysis.

Results

A total of 224 patients were included in our study; most patients (n = 201) had stage I disease. Three-year RFS rates in group 1 (n = 73), group 2 (n = 75), and group 3 (n = 53) were 74.1, 90.4, and 90.0 %, respectively. There was a significant difference in RFS between group 1 and group 2 (p = 0.009). The 3-year RFS rate in stage IIA disease was 61.4 %. There were no significant differences in RFS between group 1 and stage IIA disease (p = 0.163). In multivariate analysis, group 1 had the highest risk of recurrence (HR 5.806, p = 0.006) in stage I PA.

Conclusions

Stage I PA with a lepidic component ≤10 % was associated with an unfavorable prognosis that was similar to the prognosis of stage IIA disease. The prognosis for stage I PA should not be based on general criteria, but instead, the lepidic component should be evaluated and considered when determining disease prognosis.

Clinical impacts of a micropapillary pattern in lung adenocarcinoma: a review

Lung adenocarcinoma with a micropapillary pattern (MPPAC) has recently drawn increased attention among researchers. Micropapillary-predominant adenocarcinoma (MPA), which is defined by micropapillary pattern (MPP), is the primary histological pattern observed semiquantitatively in 5% increments on resection specimens, and MPA was formally determined to be a new histological subtype according to the new multidisciplinary classification in 2011. According to published studies, MPPAC is most common in males and nonsmokers and is associated with lymphatic invasion, pleural invasion, and lymph node metastases. MPPAC often presents as part-solid and lobulated nodules in computed tomography scans. MPP tends to have a higher maximum standardized uptake value as determined by fluorodeoxyglucose positron emission tomography combined with computed tomography, indicating a high risk of recurrence. Molecular markers, including vimentin, napsin A, phosphorylated c-Met, cytoplasmic maspin, Notch-1, MUC1, and tumoral CD10, may have higher expression in MPPAC than other subtypes; conversely, markers such as MUC4 and surfactant apoprotein A have lower expression in MPPAC. MPPAC with EGFR mutations can benefit from treatment with EGFR tyrosine kinase inhibitors. Furthermore, a complete lobectomy may be more suitable than limited resection for MPPAC because of the low sensitivity of intraoperative frozen sections and the high risk of lymph node metastasis. MPA benefits more from adjuvant chemotherapy than do other histological subtypes, whereas MPA does not benefit from adjuvant radiotherapy. Of note, MPP is associated with poor prognosis in early-stage lung adenocarcinoma, but the prognostic value of MPP is controversial in advanced-stage lung adenocarcinoma.

A comprehensive investigation of molecular features and prognosis of lung adenocarcinoma with micropapillary component

INTRODUCTION

Both micropapillary predominant lung adenocarcinoma according to the IASLC/ATS/ERS classification and lung adenocarcinoma with a micropapillary component have been reported to be associated with poor prognosis. However, whether they have different prognosis remains undetermined.

METHODS

Out of 1302 lung adenocarcinoma patients, 21 patients with micropapillary predominant lung adenocarcinoma (MPP) and 100 patients with nonmicropapillary predominant tumors harboring a micropapillary component of at least 5% (MPC) were investigated for clinicopathologic characteristics, recurrence-free survival (RFS), overall survival (OS), and spectrum of well-identified driver mutations including EGFR, KRAS, HER2, BRAF, ALK, ROS1, and RET.

RESULTS

Twenty out of 21 (95.2%) micropapillary predominant lung adenocarcinoma harbored driver mutations in EGFR (85.7%), HER2 (4.8%), or RET (4.8%). MPP had significantly worse RFS than MPC in stage I patients (p = 0.003), but not in stages II-III patients. The overall survival was comparable between MPP and MPC regardless of disease stages. Objective response was achieved in 13 out of the 18 MPP or MPC patients with EGFR mutations who received EGFR tyrosine kinase inhibitors (TKIs) after disease recurrence. The postrecurrence survival was significantly better in EGFR-mutated patients who were treated with EGFR TKIs compared to those who did not receive TKIs (p = 0.003).

CONCLUSIONS

Micropapillary predominant lung adenocarcinoma is a disease that could be largely defined by targetable driver mutations. For stage I lung adenocarcinoma, MPP was even more likely to recur than MPC. EGFR TKIs might help to control the recurrent disease for MPP or MPC patients harboring EGFR mutations.

Prevalent and up-regulated vimentin expression in micropapillary components of lung adenocarcinomas and its adverse prognostic significance

The factors conferring the increased malignancy on lung adenocarcinoma with micropapillary component (AC-MPC) remain to be elucidated. On proteomics based on 2-dimensional gel electrophoresis, 19 proteins differentially expressed by more than 1.5-fold between AC-MPC and conventional adenocarcinoma (CAC); in particular, vimentin, one of the proteins, was 3.5-fold up-regulated in AC-MPC. Subsequent semi-quantitative investigation by immunohistochemistry with large cohorts comprised 101 AC-MPC and 119 CAC, respectively, of different stages revealed that vimentin was expressed in MPC of 95 (94.1%) AC-MPC and the expression scores were higher than those of well- and moderately differentiated CAC, as well as the background non-MPC of the AC-MPC (P < 0.0001), but not significantly different from those of poorly differentiated CAC (P = 0.561). Even within the AC-MPC entity, higher vimentin expression was correlated with more frequent vascular invasion and more advanced node metastasis (P < 0.02), and multivariate analysis showed that high vimentin expression and worse node statuses were independent indicators of adverse prognosis (P < 0.048). In conclusion, vimentin expression is prevalent and markedly up-regulated in MPC, which might reflect the biological essence of poorer differentiation or dedifferentiation of MPC, and this might have a role in the acquisition and increase of invasiveness and consequent more malignant nature of MPC.

Using frozen section to identify histological patterns in stage I lung adenocarcinoma of ≤ 3 cm: accuracy and interobserver agreement

AIMS

The IASLC/ATS/ERS classification of lung adenocarcinoma provides a prognostically significant histological subclassification. The aim of this study was to investigate the accuracy, limitations and interobserver agreement of frozen sections for predicting histological subtype.

METHODS AND RESULTS

Frozen section and permanent section slides from 361 resected stage I lung adenocarcinomas ≤ 3 cm in size were reviewed for predominant histological subtype and the presence or absence of lepidic, acinar, papillary, micropapillary and solid patterns. Fifty cases were additionally reviewed by three pathologists to determine interobserver agreement. To test the accuracy of frozen section in judging degree of invasion, five pathologists reviewed frozen section slides from 35 cases with a predominantly lepidic pattern. There was moderate agreement on predominant histological subtype between frozen sections and final diagnosis (κ = 0.565). Frozen sections had high specificity for micropapillary and solid patterns (94% and 96%, respectively), but sensitivity was low (37% and 69%, respectively). The interobserver agreement was satisfactory (κ > 0.6, except for the acinar pattern).

CONCLUSIONS

Frozen section can provide information on the presence of aggressive histological patterns-micropapillary and solid-with high specificity but low sensitivity. It was difficult to predict the predominant pattern on the basis of frozen sections, mostly because of sampling issues.

Pulmonary adenocarcinoma: implications of the recent advances in molecular biology, treatment and the IASLC/ATS/ERS classification

A decade ago, lung cancer could conveniently be classified into two broad categories-either the small cell lung carcinoma (SCLC), or the non-small cell lung carcinoma (NSCLC), mainly to assist in further treatment related decision making. However, the understanding regarding the eligibility of adenocarcinoma histology for treatments with agents such as pemetrexed and bevacizumab made it a necessity for NSCLC to be classified into more specific sub-groups. Then, the availability of molecular targeted therapy with oral tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib not only further emphasized the need for accurate sub-classification of lung cancer, but also heralded the important role of molecular profiling of lung adenocarcinomas. Given the remarkable advances in molecular biology, oncology and radiology, a need for felt for a revised classification for lung adenocarcinoma, since the existing World Health Organization (WHO) classification of lung cancer, published in the year 2004 was mainly a pathological system of classification. Thus, there was a combined effort by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS) and the European Respiratory Society (ERS) with an effort to inculcate newly established perspectives from clinical, molecular and radiological aspects in evolving a modern classification for lung adenocarcinomas. This review provides a summary of the recent advances in molecular biology and molecular targeted therapy with respect to lung adenocarcinoma. Also, a brief summation of the salient recommendations provided in the IASLC/ATS/ERS classification of lung adenocarcinomas is provided. Lastly, a discussion regarding the future prospects with lung adenocarcinoma is included.

Recent advances and clinical implications of the micropapillary histological subtype in lung adenocarcinomas

Micropapillary (MIP) histologic subtype included in the classification of lung adenocarcinomas (ADCs) is associated with both size- and stage-independent poor prognoses. MIP pattern in lung ADCs, even at small, early stages, correlates with high lymphovascular invasion, visceral pleural invasion and lymph node metastases. Recently, we reported that patients with a MIP component are at a higher risk of locoregional recurrence after limited resection. Identification of a MIP pattern is only possible with permanent pathologic sections; preoperative imaging, cytology or intraoperative frozen section specimens remain unreliable. The intermixed, heterogenous morphology of lung ADC presents a technical challenge in investigating the molecular biology of cells with MIP morphology. A comprehensive understanding of the biology of MIP morphology is vital for therapeutic interventions.

Cytodiagnostic aspects of lung adenocarcinoma manifesting with micropapillary pattern in sputum: a case report of potential diagnostic pitfall

The micropapillary pattern of lung adenocarcinoma was discussed in the 2004 World Health Organization classification and is now proposed as a distinct pattern in the new International Multidisciplinary Classification of Lung Adenocarcinoma Guidelines. The micropapillary pattern is histologically characterized by papillary tufts lacking a central fibrovascular core and is associated with an unfavorable prognosis. Herein, we report the cytological features of lung adenocarcinoma with the micropapillary pattern in a sputum specimen. A 75-year-old woman presented with a productive cough, blood-tinged sputum, and some symptoms of upper respiratory tract infection. The initial impressions from her chest radiograph and computed tomography scan indicated pneumonia. However, the initial sputum cytology sample showed a few clusters of cells with abnormal three-dimensional structure, interpreted as adenocarcinoma. These cells were small and had minimal cytologic atypia, demonstrating a potential diagnostic pitfall. The following biopsy confirmed lung adenocarcinoma with the micropapillary pattern. Here, we describe this case and discuss the differential diagnosis of pulmonary entities exhibiting similar morphologies.

Association of c-Met phosphorylation with micropapillary pattern and small cluster invasion in pT1-size lung adenocarcinoma

Lung adenocarcinomas with micropapillary pattern (MPP) are associated with frequent nodal metastasis. However, little is known about the mechanisms that underlie MPP-associated nodal metastasis. We have previously reported that pT1 lung adenocarcinomas with MPP are significantly associated with small cluster invasion (SCI) and lymphatic involvement. SCI is defined as markedly resolved acinar-papillary tumor structures with single or small clusters of carcinoma cells invading stroma within fibrotic foci. In this study, we hypothesized that c-Met activation may be involved in the MPP-SCI sequence, given that the c-Met tyrosine-kinase receptor and its ligand hepatocyte growth factor (HGF), play important roles in tumor cell motility and invasion. We analyzed 125 pT1-size lung adenocarcinomas for immunohistochemical expression of phosphorylated c-Met and its correlation with MPP, SCI, lymphatic involvement and prognosis. SCI was significantly more frequent in the MPP-positive group (P<0.0001) and associated with lymphatic involvement (P<0.0001) and nodal metastasis (P=0.021). c-Met protein was detected in all tumors by immunohistochemistry as membranous and cytoplasmic staining. Phospho-c-Met (pc-Met) was positive in 119/125 tumors (95%) and expressed at high levels in 27 cases (22%). A high level of pc-Met expression was significantly associated with MPP (P=0.01) and SCI (P=0.0059). Moreover, in tumors with MPP or SCI, those expressing high levels of pc-Met were significantly more associated with lymphatic involvement. In p-Stage IA lung adenocarcinomas (n=99), patients in the high pc-Met expression group showed significantly worse survival than patient in the low expression group (P=0.0313). These results suggest that activation of c-Met through phosphorylation may be involved in MPP and SCI.