Clinical relevance of neuroendocrine differentiation in non-small cell lung cancer assessed by immunohistochemistry: a retrospective study on 405 surgically resected cases

Diagnostic gastrointestinal markers in primary lung cancer and pulmonary metastases

Histopathological diagnosis of pulmonary tumors is essential for treatment decisions. The distinction between primary lung adenocarcinoma and pulmonary metastasis from the gastrointestinal (GI) tract may be difficult. Therefore, we compared the diagnostic value of several immunohistochemical markers in pulmonary tumors. Tissue microarrays from 629 resected primary lung cancers and 422 resected pulmonary epithelial metastases from various sites (whereof 275 colorectal cancer) were investigated for the immunohistochemical expression of CDH17, GPA33, MUC2, MUC6, SATB2, and SMAD4, for comparison with CDX2, CK20, CK7, and TTF-1. The most sensitive markers for GI origin were GPA33 (positive in 98%, 60%, and 100% of pulmonary metastases from colorectal cancer, pancreatic cancer, and other GI adenocarcinomas, respectively), CDX2 (99/40/100%), and CDH17 (99/0/100%). In comparison, SATB2 and CK20 showed higher specificity, with expression in 5% and 10% of mucinous primary lung adenocarcinomas and both in 0% of TTF-1-negative non-mucinous primary lung adenocarcinomas (25-50% and 5-16%, respectively, for GPA33/CDX2/CDH17). MUC2 was negative in all primary lung cancers, but positive only in less than half of pulmonary metastases from mucinous adenocarcinomas from other organs. Combining six GI markers did not perfectly separate primary lung cancers from pulmonary metastases including subgroups such as mucinous adenocarcinomas or CK7-positive GI tract metastases. This comprehensive comparison suggests that CDH17, GPA33, and SATB2 may be used as equivalent alternatives to CDX2 and CK20. However, no single or combination of markers can categorically distinguish primary lung cancers from metastatic GI tract cancer.

Clonal Origin and Lineage Ambiguity in Mixed Neuroendocrine Carcinoma of the Uterine Cervix

Small-cell neuroendocrine carcinoma (SCNEC) of the cervix is a rare disease characterized by a high incidence of mixed tumors with other types of cancer. The mechanism underlying this mixed phenotype is not well understood. This study established a panel of organoid lines from patients with SCNEC of the cervix and ultimately focused on one line, which retained a mixed tumor phenotype, both in vitro and in vivo. Histologically, both organoids and xenograft tumors showed distinct differentiation into either SCNEC or adenocarcinoma in some regions and ambiguous differentiation in others. Tracking single cells indicated the existence of cells with bipotential differentiation toward SCNEC and adenocarcinomas. Single-cell transcriptional analysis identified three distinct clusters: SCNEC-like, adenocarcinoma-like, and a cluster lacking specific differentiation markers. The expression of neuroendocrine markers was enriched in the SCNEC-like cluster but not exclusively. Human papillomavirus 18 E6 was enriched in the SCNEC-like cluster, which showed higher proliferation and lower levels of the p53 pathway. After treatment with anticancer drugs, the expression of adenocarcinoma markers increased, whereas that of SCNEC decreased. Using a reporter system for keratin 19 expression, changes in the differentiation of each cell were shown to be associated with the shift in differentiation induced by drug treatment. These data suggest that mixed SCNEC/cervical tumors have a clonal origin and are characterized by an ambiguous and flexible differentiation state.

Comparison of INSM1 immunostaining with established neuroendocrine markers synaptophysin and chromogranin A in over 14,000 neuroendocrine and non-neuroendocrine tumors

INSM1 is a transcription factor protein which is increasingly used as an immunohistochemical marker for neuroendocrine differentiation. To determine the prevalence of INSM1 expression in tumors and its expression pattern in normal tissues, tissue microarrays containing 14,908 samples from 117 different tumor types/subtypes as well as 76 different normal tissues were analyzed by immunohistochemistry. INSM1 was positive in 89.2% of 471 neuroendocrine neoplasms (NEN) and in 3.5% of 11,815 non-neuroendocrine neoplasms that were successfully analyzed. At least an occasional weak INSM1 positivity was observed in 59 different non-neuroendocrine tumor entities, of which 15 entities contained at least one case with strong INSM1 staining. A comparison with synaptophysin and chromogranin A staining revealed that in NEN, synaptophysin showed the highest sensitivity (93.3%), followed by INSM1 (89.2%) and chromogranin A (87.5%). In neuroendocrine carcinomas (NEC), sensitivity was highest for INSM1 (88.0%), followed by synaptophysin (86.5%) and chromogranin A (66.4%). If INSM1 was used as an additional marker, the sensitivity for detecting neuroendocrine differentiation in NEN increased from 96.6% (synaptophysin and chromogranin A) to 97.2% (synaptophysin, chromogranin A and INSM1). Our study shows that INSM1 is a useful additional marker for neuroendocrine differentiation with high sensitivity, particularly in NEC.

High expression of insulinoma-associated protein 1 (INSM1) distinguishes colorectal mixed and pure neuroendocrine carcinomas from conventional adenocarcinomas with diffuse expression of synaptophysin

Complementary to synaptophysin and chromogranin A, insulinoma-associated protein 1 (INSM1) has emerged as a sensitive marker for the diagnosis of neuroendocrine neoplasms. Since there are no comparative data regarding INSM1 expression in conventional colorectal adenocarcinomas (CRCs) and colorectal mixed adenoneuroendocrine carcinomas/neuroendocrine carcinomas (MANECs/NECs), we examined INSM1 in a large cohort of conventional CRCs and MANECs/NECs. In conventional CRC, we put a special focus on conventional CRC with diffuse expression of synaptophysin, which carry the risk of being misinterpreted as a MANEC or a NEC. We investigated INSM1 according to the immunoreactive score in our main cohort of 1,033 conventional CRCs and 21 MANECs/NECs in comparison to the expression of synaptophysin and chromogranin A and correlated the results with clinicopathological parameters and patient survival. All MANECs/NECs expressed INSM1, usually showing high or moderate expression (57% high, 34% moderate, and 9% low), which distinguished them from conventional CRCs, which were usually INSM1 negative or low, even if they diffusely expressed synaptophysin. High expression of INSM1 was not observed in conventional CRCs. Chromogranin A was negative/low in most conventional CRCs (99%), but also in most MANECs/NECs (66%). Comparable results were observed in our independent validation cohorts of conventional CRC (n = 274) and MANEC/NEC (n = 19). Similar to synaptophysin, INSM1 expression had no prognostic relevance in conventional CRCs, while true MANEC/NEC showed a highly impaired survival in univariate and multivariate analyses (e.g. disease-specific survival: p < 0.001). MANECs/NECs are a highly aggressive variant of colorectal cancer, which must be reliably identified. High expression of INSM1 distinguishes MANEC/NEC from conventional CRCs with diffuse expression of the standard neuroendocrine marker synaptophysin, which do not share the same dismal prognosis. Therefore, high INSM1 expression is a highly specific/sensitive marker that is supportive for the diagnosis of true colorectal MANEC/NEC.

Updates in pathology and molecular diagnostics to inform the evolving landscape of thoracic surgery and oncology

The pathologic assessment of lung cancers provides essential guidance to the surgeon and oncologist who are considering the best treatment strategies for patients with both early and advanced-stage disease. The management of patients with lung cancer is predicated first and foremost on access to an accurate diagnosis, even when the sample size is limited, as is often the case with use of modern, minimally invasive sampling techniques. Once the diagnosis and disease stage are established, predictive biomarker testing may be essential, particularly for those patients with nonsmall cell lung carcinoma (NSCLC) being considered for immunotherapy or genomic biomarker-driven targeted therapy. This review will discuss the best practices for the diagnosis of NSCLC using morphology and immunohistochemistry, thus providing the surgeon with needed information to understand and critically evaluate pathology reports. Controversial and evolving topics including tumor spread through airspaces, evaluation of multiple tumors, and staging based on invasive tumor size will be addressed. Clinical genomic profiling in NSCLC is driven by published guidelines and reflects evidence based on clinical trials and regulatory approvals. In this fast-moving space, surgeons should be aware of the critical immunohistochemical and genomic biomarkers that drive systemic therapy decisions and anticipate when such testing will be required, both to ensure adequate sampling and to advise the pathologist when tumor material will be required for biomarker analysis. The basic approaches to and sample requirements for molecular biomarker testing will be addressed. As biomarker testing moves exclusively from advanced-stage patients into earlier stage disease, the surgeon should be aware of the relevant markers and work with the pathologist and oncologist to ensure that this information is available to facilitate timely access to therapies not just in the advanced setting, but in consideration of neoadjuvant and adjuvant care.

Neuroendocrine differentiation distinguishes basaloid variant of lung squamous cell carcinoma

Background

Neuroendocrine (NE) differentiation is widely studied in non-small cell lung carcinomas (NSCLC) however, its significance remains unclear in basaloid squamous cell carcinomas (B-SqCC). This study aims to assess the extent of NE differentiation in B-SqCC and characterize the underlying molecular process.

Methods

This study evaluated resected B-SqCC, small cell lung cancer (SCLC) and poorly differentiated SqCC (PD-SqCC) from 2005 to 2020 at the Ottawa Hospital. Samples were subject to pathological review, immunohistochemistry (IHC) and survival analysis. Gene expression analysis was performed on B-SqCC samples exhibiting NE+ and NE- regions (paired samples) to identify differentially expressed genes (DEGs). These DEGs were subsequently validated in unpaired B-SqCC and TCGA samples.

Results

B-SqCC cases were more likely to exhibit nuclear molding, resetting and peripheral palisading than PD-SqCC. B-SqCC were also more likely to demonstrate NE differentiation compared to PD-SqCC (p = 0.006). Pure basaloid squamous cell carcinoma (PB-SqCC) experienced poorer disease-free survival (HR = 3.12, p = 0.043) adjusted for stage.

Molecular characterization of paired B-SqCC samples demonstrated DEGs implicated in NOTCH signaling, SCLC and pulmonary neuroendocrine differentiation. Hierarchical clustering using discovered DEGs in unpaired B-SqCC samples distinguished tumors based on NE status (p = 0.048). Likewise, clustering The Cancer Genome Atlas (TCGA) samples with DEGs distinguished B-SqCC from SqCC samples (p = 0.0094).

Conclusion

This study provides IHC and molecular evidence of significant NE-differentiation in B-SqCC and demonstrates their aggressive clinical behavior. These findings suggest that B-SqCC are biologically distinct from SqCC and share characteristics with SCLC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-022-01223-6.

Cluster Analysis According to Immunohistochemistry is a Robust Tool for Non-Small Cell Lung Cancer and Reveals a Distinct, Immune Signature-defined Subgroup

Clustering in medicine is the subgrouping of a cohort according to specific phenotypical or genotypical traits. For breast cancer and lymphomas, clustering by gene expression profiles has already resulted in important prognostic and predictive subgroups. For non-small cell lung cancer (NSCLC), however, little is known. We performed a cluster analysis on a cohort of 365 surgically resected, well-documented NSCLC patients, which was followed-up for a median of 62 months, incorporating 70 expressed proteins and several genes. Our data reveal that tumor grading by architecture is significant, that large cell carcinoma is likely not a separate entity, and that an immune signature cluster exists. For squamous cell carcinomas, a prognostically relevant cluster with poorer outcome was found, defined by a high CD4/CD8 ratio and lower presence of granzyme B+ tumor-infiltrating lymphocytes (TIL). This study shows that clustering analysis is a useful tool for verifying established characteristics and generating new insights for NSCLC. Importantly, for one "immune signature" cluster, the signature of the TIL (especially the amount of CD8+ TIL) was more crucial than the histologic or any other phenotypical aspect. This may be an important finding toward explaining why only a fraction of eligible patients respond to immunomodulating anticancer therapies.

Role of Synaptophysin, Chromogranin and CD56 in adenocarcinoma and squamous cell carcinoma of the lung lacking morphological features of neuroendocrine differentiation: a retrospective large-scale study on 1170 tissue samples

BACKGROUND

Synaptophysin, chromogranin and CD56 are recommended markers to identify pulmonary tumors with neuroendocrine differentiation. Whether the expression of these markers in pulmonary adenocarcinoma and pulmonary squamous cell carcinoma is a prognostic factor has been a matter of debate. Therefore, we investigated retrospectively a large cohort to expand the data on the role of synaptophysin, chromogranin and CD56 in non-small cell lung cancer lacking morphological features of neuroendocrine differentiation.

METHODS

A cohort of 627 pulmonary adenocarcinomas (ADC) and 543 squamous cell carcinomas (SqCC) lacking morphological features of neuroendocrine differentiation was assembled and a tissue microarray was constructed. All cases were stained with synaptophysin, chromogranin and CD56. Positivity was defined as > 1% positive tumor cells. Data was correlated with clinico-pathological features including overall and disease free survival.

RESULTS

110 (18%) ADC and 80 (15%) SqCC were positive for either synaptophysin, chromogranin, CD56 or a combination. The most commonly positive single marker was synaptophysin. The least common positive marker was chromogranin. A combination of ≤2 neuroendocrine markers was positive in 2-3% of ADC and 0-1% of SqCC. There was no significant difference in overall survival in tumors with positivity for neuroendocrine markers neither in ADC (univariate: P = 0.4; hazard ratio [HR] = 0.867; multivariate: P = 0.5; HR = 0.876) nor in SqCC (univariate: P = 0.1; HR = 0.694; multivariate: P = 0.1, HR = 0.697). Likewise, there was no significant difference in disease free survival.

CONCLUSIONS

We report on a cohort of 1170 cases that synaptophysin, chromogranin and CD56 are commonly expressed in ADC and SqCC and that their expression has no impact on survival, supporting the current best practice guidelines.

Mediastinal Neuroendocrine Carcinoma Slowly Growing for 8 Years after Surgical Resection of Esophageal Squamous Cell Carcinoma

A 70-year-old woman was referred to our department due to a solitary mediastinal tumor which gradually grew near the site of anastomosis for 8 years after radical surgery of esophageal squamous cell carcinoma. It was difficult to distinguish the lymph node recurrence of esophageal cancer from another tumor of unknown primary origin. Endoscopic ultrasound-guided fine-needle aspiration was performed, and the tumor was diagnosed to be neuroendocrine carcinoma. She received concurrent chemoradiotherapy with etoposide plus cisplatin. After the completion of chemoradiotherapy, the tumor disappeared. A solitary growing tumor which develops after radical resection of cancer would be better to be examined histologically in order to make an accurate diagnosis and select the most appropriate treatment.

Diagnostic Value of Insulinoma-Associated Protein 1 (INSM1) and Comparison With Established Neuroendocrine Markers in Pulmonary Cancers

CONTEXT.—

The diagnostic distinction of pulmonary neuroendocrine (NE) tumors from non-small cell lung carcinomas (NSCLCs) is clinically relevant for prognostication and treatment. Diagnosis is based on morphology and immunohistochemical staining.

OBJECTIVE.—

To determine the diagnostic value of insulinoma-associated protein 1 (INSM1), in comparison with established NE markers, in pulmonary tumors.

DESIGN.—

Fifty-four pulmonary NE tumors and 632 NSCLCs were stained for INSM1, CD56, chromogranin A, and synaptophysin. In a subset, gene expression data were available for analysis. Also, 419 metastases to the lungs were stained for INSM1. A literature search identified 39 additional studies with data on NE markers in lung cancers from the last 15 years. Seven of these included data on INSM1.

RESULTS.—

A positive INSM1 staining was seen in 39 of 54 NE tumors (72%) and 6 of 623 NSCLCs (1%). The corresponding numbers were 47 of 54 (87%) and 14 of 626 (2%) for CD56, 30 of 54 (56%) and 6 of 629 (1%) for chromogranin A, and 46 of 54 (85%) and 49 of 630 (8%) for synaptophysin, respectively. Analysis of literature data revealed that CD56 and INSM1 were the best markers for identification of high-grade NE pulmonary tumors when considering both sensitivity and specificity, while synaptophysin also showed good sensitivity. INSM1 gene expression was clearly associated with NE histology.

CONCLUSIONS.—

The solid data of both our and previous studies confirm the diagnostic value of INSM1 as a NE marker in pulmonary pathology. The combination of CD56 with INSM1 and/or synaptophysin should be the first-hand choice to confirm pulmonary high-grade NE tumors. INSM1 gene expression could be used to predict NE tumor histology.

New molecular classification of large cell neuroendocrine carcinoma and small cell lung carcinoma with potential therapeutic impacts

Large cell neuroendocrine carcinoma (LCNECs) and small cell lung carcinomas (SCLCs) are high-grade neuroendocrine carcinomas of the lung with very aggressive behavior and poor prognosis. Their histological classification as well as their therapeutic management has not changed much in recent years, but genomic and transcriptomic analyses have revealed different molecular subtypes raising hopes for more personalized treatment. Indeed, four subtypes of SCLCs have been recently described, SCLC-A driven by the master gene ASCL1, SCLC-N driven by NEUROD1, SCLC-Y by YAP1 and SCLC-P by POU2F3. Whereas SCLC standard of care is based on concurrent chemoradiation for limited stages and on chemotherapy alone or chemotherapy combined with anti-PD-L1 checkpoint inhibitors for extensive stage SCLC, SCLC-A variants could benefit from DLL3 or BCL2 inhibitors, and SCLC-N variants from Aurora kinase inhibitors combined with chemotherapy, or PI3K/mTOR or HSP90 inhibitors. In addition, a new SCLC variant (SCLC-IM) with high-expression of immune checkpoints has been also reported, which could benefit from immunotherapies. PARP inhibitors also gave promising results in combination with chemotherapy in a subset of SCLCs. Regarding LCNECs, they represent a heterogeneous group of tumors, some of them exhibiting mutations also found in SCLC but with a pattern of expression of NSCLC, while others harbor mutations also found in NSCLC but with a pattern of expression of SCLC, questioning their clinical management as NSCLCs or SCLCs. Overall, we are probably entering a new area, which, if personalized treatments are effective, will also lead to the implementation in practice of molecular testing or biomarkers detection for the selection of patients who can benefit from them.

Multiple faces of pulmonary large cell neuroendocrine carcinoma: update with a focus on practical approach to diagnosis

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a rare and aggressive malignancy that is strongly linked to smoking and notoriously difficult to diagnose and treat. Recent molecular data reveal that it represents a biologically heterogeneous group of tumors, characterized by morphologic and genomic diversity that straddles small cell and non-small cell lung carcinomas (NSCLCs), and in a minority of cases atypical carcinoids. This review provides an update on recent molecular and clinical developments in LCNEC with the main focus on practical approach to pathologic diagnosis using illustrative examples of the main differential diagnostic considerations.

Immunohistochemistry in the diagnosis and classification of neuroendocrine neoplasms: what can brown do for you?

This review is based on a presentation given at the Hans Popper Hepatopathology Society companion meeting at the 2019 United States and Canadian Academy of Pathology Annual Meeting. It presents updates on the diagnosis and classification of neuroendocrine neoplasms, with an emphasis on the role of immunohistochemistry. Neuroendocrine neoplasms often present in liver biopsies as metastases of occult origin. Specific topics covered include 1. general features of neuroendocrine neoplasms, 2. general neuroendocrine marker immunohistochemistry, with discussion of the emerging marker INSM1, 3. non-small cell carcinoma with (occult) neuroendocrine differentiation, 4. the WHO Classification of neuroendocrine neoplasms, with discussion of the 2019 classification of gastroenteropancreatic neoplasms, 5. use of Ki-67 immunohistochemistry, 6. immunohistochemistry to assign site of origin in neuroendocrine metastasis of occult origin, 7. immunohistochemistry to distinguish well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma, 8. lesions frequently misdiagnosed as well-differentiated neuroendocrine tumor, and 9. required and recommended data elements for biopsies and resections with associated immunohistochemical stains. Next-generation immunohistochemistry, including lineage-restricted transcription factors (e.g., CDX2, islet 1, OTP, SATB2) and protein correlates of molecular genetic events (e.g., p53, Rb), is indispensable for the accurate diagnosis and classification of these neoplasms.

Insulinoma-associated protein 1 is a sensitive and specific marker for lung neuroendocrine tumors in cytologic and surgical specimens

INTRODUCTION

Insulinoma-associated protein 1 (INSM1) is an immunohistochemical marker for neuroendocrine differentiation with potentially superior sensitivity and specificity. INSM1 performance in pulmonary cytology cell block material (CB) has not been well established, and large series demonstrating its performance have been few.

MATERIALS AND METHODS

Typical and atypical carcinoid, small cell lung carcinoma, and large cell neuroendocrine carcinoma, squamous cell carcinoma, and adenocarcinoma CBs and 563 surgical specimens comprising 17 typical carcinoid, 14 atypical carcinoid, 8 small cell lung carcinoma, 10 large cell neuroendocrine carcinoma, 58 squamous cell carcinoma, 415 adenocarcinoma, and 17 large cell carcinoma cases and 24 other tumor types were immunostained with INSM1, CD56, synaptophysin, and chromogranin A.

RESULTS

The INSM1 sensitivity, specificity, positive predictive value, and negative predictive value were 92.3%, 100%, 78.9%, and 99% in the CBs and 89.8%, 98.1%, 81.5%, and 99% in the surgical specimens, respectively, with 86.2% concordance. The sensitivity, specificity, positive predictive value, and negative predictive value for the other neuroendocrine markers were 97.4%, 93.3%, 97.4%, and 93.3% in the CBs and 93.9%, 93.6%, 58.2%, and 99.4% in the surgical specimens for CD56; 89.7%, 100%, 100%, and 75% in the CBs and 93.4%, 91.2%, 50.5%, and 99.4% in the surgical specimens for synaptophysin; 66.7%, 100%, 100%, and 53.6% in the CBs and 75.5%, 98.6%, 84.1%, and 97.7% in the surgical specimens for chromogranin A, respectively. Finally, INSM1, together with CD56, maximized the sensitivity to 100% with 93.3% specificity in the CBs.

CONCLUSIONS

The results from our study have further established the high sensitivity and specificity of INSM1 in the largest pulmonary cytologic and surgical cohorts to date. INSM1 either matched or outperformed the performance of existing neuroendocrine markers, and its combination with CD56 appeared to maximize test performance.

[Immunophenotyping of lung tumors : An update]

The WHO Classification of Lung Tumors (2015) established the use of immunohistochemical stainings for resection specimens, however, detailed recommendations had been missing. Now, an international expert panel has summarized key questions for daily routine practice and provided recommendations to assist the community in the appropriate use of immunohistochemistry in this context. This article provides an overview of the most important aspects.

Recent advances in the molecular landscape of lung neuroendocrine tumors

INTRODUCTION

Neuroendocrine tumors of the lung (Lung-NETs) make up a heterogenous family of neoplasms showing neuroendocrine differentiation and encompass carcinoids and neuroendocrine carcinomas. On molecular grounds, they considered two completely distinct and separate tumor groups with no overlap of molecular alterations nor common developmental mechanisms. Areas covered: Two perspectives were evaluated based on an extensive review and rethinking of literature: (1) the current classification as an instrument to obtaining clinical and molecular insights into the context of Lung-NETs; and (2) an alternative and innovative interpretation of these tumors, proposing a tripartite separation into early aggressive primary high-grade neuroendocrine tumors (HGNET), differentiating or secondary HGNET, and indolent NET. Expert opinion: We herein provide an alternative outlook on Lung-NETs, which is a paradigm shift to current pathogenesis models and expands the understanding of these tumors.

Best Practices Recommendations for Diagnostic Immunohistochemistry in Lung Cancer

Since the 2015 WHO classification was introduced into clinical practice, immunohistochemistry (IHC) has figured prominently in lung cancer diagnosis. In addition to distinction of small cell versus non-small cell carcinoma, patients' treatment of choice is directly linked to histologic subtypes of non-small cell carcinoma, which pertains to IHC results, particularly for poorly differentiated tumors. The use of IHC has improved diagnostic accuracy in the classification of lung carcinoma, but the interpretation of IHC results remains challenging in some instances. Also, pathologists must be aware of many interpretation pitfalls, and the use of IHC should be efficient to spare the tissue for molecular testing. The International Association for the Study of Lung Cancer Pathology Committee received questions on practical application and interpretation of IHC in lung cancer diagnosis. After discussions in several International Association for the Study of Lung Cancer Pathology Committee meetings, the issues and caveats were summarized in terms of 11 key questions covering common and important diagnostic situations in a daily clinical practice with some relevant challenging queries. The questions cover topics such as the best IHC markers for distinguishing NSCLC subtypes, differences in thyroid transcription factor 1 clones, and the utility of IHC in diagnosing uncommon subtypes of lung cancer and distinguishing primary from metastatic tumors. This article provides answers and explanations for the key questions about the use of IHC in diagnosis of lung carcinoma, representing viewpoints of experts in thoracic pathology that should assist the community in the appropriate use of IHC in diagnostic pathology.

Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?

Aims

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is underdiagnosed on biopsy specimens. We evaluated if routine neuroendocrine immunohistochemical (IHC) stains are helpful in the diagnosis of LCNEC on biopsy specimens.

Methods and results

Using the Dutch pathology registry (PALGA), surgically resected LCNEC with matching pre‐operative biopsy specimens were identified and haematoxylin and IHC slides (CD56, chromogranin‐A, synaptophysin) requested. Subsequently, three pathologists assigned (1) the presence or absence of the WHO 2015 criteria and (2) cumulative size of all (biopsy) specimens. For validation, a tissue microarray (TMA) of non‐small‐cell lung cancer (NSCLC) (n = 77) and LCNEC (n = 19) was used. LCNEC was confirmed on the resection specimens in 32 of 48 re‐reviewed cases. In 47% (n = 15 of 32) LCNEC was also confirmed in the paired biopsy specimens. Neuroendocrine morphology was absent in 53% (n = 17 of 32) of paired biopsy specimens, more often when smaller amounts of tissue were available for evaluation [29% < 5 mm (n = 14) versus 67% ≥5 mm (n = 18) P = 0.04]. Combined with current WHO criteria, positive staining for greater than or equal to two of three neuroendocrine IHC markers increased the sensitivity for LCNEC from 47% to 93% on paired biopsy specimens, and further validated using an independent TMA of LCNEC and NSCLC with sensitivity and specificity of 80% and 99%, respectively.

Conclusions

LCNEC is difficult to diagnose because neuroendocrine morphology is frequently absent in biopsy specimens. In NSCLC devoid of obvious morphological squamous or adenocarcinoma features, positive staining in greater than or equal to two of three neuroendocrine IHC stains supports the diagnosis of LCNEC.

Diagnostic and prognostic impact of mucin 1-6 expression in non-small cell lung cancer

Background

The prognostic significance and clinico-pathological characterization of mucin (MUC) expression in non-small cell lung cancer (NSCLC) is controversial and little studied.

Aims

This study aims at elucidating this issue on the largest and most detailed cohort so far.

Settings and Design

We examined the expression of MUC 1, 2, 4, 5AC and 6 on 371, well documented, surgically resected NSCLC cases.

Materials and Methods

Immunohistochemical results were correlated with several of our previously studied, relevant parameters on this cohort including a follow-up period of up to 20 years. An additional point we examined for practical reasons that has not been addressed so far, was the possible assistance of MUC expression for the differentiation between a primary lung adenocarcinoma and metastasis from a known pancreatobiliary primary tumor.

Statistical Analysis Used

Cronbach's Alpha reliability correlation, Spearman's correlation, ANOVA means of comparison with additional Kruskall-Wallis H-test, and Kaplan-Meier survival analysis were employed as statistical analyses in this study.

Results and Conclusions

MUCs were associated with histologic subtypes, tumor differentiation and members of the epidermal growth factor receptor signaling pathway, although they were not found to be significant for prognosis. Expression of MUC1 correlated with certain other markers and may point to a group of patients relevant for upcoming treatment strategies involving MUC1. According to our findings, we also recommend additional MUC5AC staining for a thyroid transcription factor 1-negative adenocarinoma in the lung for the differentiation of a possible metastasis in the presence of a pancreatic ductal adenocarcinoma.

LMO1 functions as an oncogene by regulating TTK expression and correlates with neuroendocrine differentiation of lung cancer

LMO1 encodes a protein containing a cysteine-rich LIM domain involved in protein-protein interactions. Recent studies have shown that LMO1 functions as an oncogene in several cancer types, including non-small cell lung cancer (NSCLC). However, the function of LMO1 in other histological subtypes of lung cancer, such as small cell lung cancer (SCLC), was not investigated. In analyzing the expression of LMO1 across a panel of lung cell lines, we found that LMO1 expression levels were significantly and dramatically higher in SCLC cells, an aggressive neuroendocrine subtype of lung cancer, relative to NSCLC and normal lung cells. In NSCLC cells, LMO1 mRNA levels were significantly correlated with expression of neuroendocrine differentiation markers. Our in vitro investigations indicated that LMO1 had the general property of promoting cell proliferation in lung cancer cells representing different histological subtypes, suggesting a general oncogenic function of LMO1 in lung cancer. In investigating the clinical relevance of LMO1 as an oncogene, we found that a high tumor level of the LMO1 mRNA was an independent predictor of poor patient survival. These results suggest that LMO1 acts as an oncogene, with expression correlated with neuroendocrine differentiation of lung cancer, and that it is a determinant of lung cancer aggressiveness and prognosis. By combining gene expression correlations with patient survival and functional in vitro investigations, we further identified TTK as mediating the oncogenic function of LMO1 in lung cancer cells.

Nuclear receptor NR2F6 inhibition potentiates responses to PD-L1/PD-1 cancer immune checkpoint blockade

Analyzing mouse tumor models in vivo, human T cells ex vivo, and human lung cancer samples, we provide direct evidence that NR2F6 acts as an immune checkpoint. Genetic ablation of Nr2f6, particularly in combination with established cancer immune checkpoint blockade, efficiently delays tumor progression and improves survival in experimental mouse models. The target genes deregulated in intratumoral T lymphocytes upon genetic ablation of Nr2f6 alone or together with PD-L1 blockade reveal multiple advantageous transcriptional alterations. Acute Nr2f6 silencing in both mouse and human T cells induces hyper-responsiveness that establishes a non-redundant T-cell-inhibitory function of NR2F6. NR2F6 protein expression in T-cell-infiltrating human NSCLC is upregulated in 54% of the cases (n = 303) and significantly correlates with PD-1 and CTLA-4 expression. Our data define NR2F6 as an intracellular immune checkpoint that suppresses adaptive anti-cancer immune responses and set the stage for clinical validation of targeting NR2F6 for next-generation immuno-oncological regimens.

Immune checkpoints blockade (ICB) is a viable anti-cancer strategy. Here the authors show that nuclear receptor NR2F6 acts as an immune checkpoint in T cells and, using mouse models and human T cells, they show NR2F6 inhibition might improve current ICB therapy or work as an alternative therapeutic strategy.

INSM1 Demonstrates Superior Performance to the Individual and Combined Use of Synaptophysin, Chromogranin and CD56 for Diagnosing Neuroendocrine Tumors of the Thoracic Cavity

Despite the importance of recognizing neuroendocrine differentiation when diagnosing tumors of the thoracic cavity, the sensitivity of traditional neuroendocrine markers is suboptimal, particularly for high-grade neuroendocrine carcinomas such as small cell lung carcinoma and large cell neuroendocrine carcinoma. To increase sensitivity, neuroendocrine markers are routinely ordered as panels of multiple immunostains where any single positive marker is regarded as sufficient evidence of neuroendocrine differentiation. Insulinoma-associated protein 1 (INSM1) is a well-validated transcription factor of neuroendocrine differentiation that has only recently been evaluated for diagnostic use. We performed INSM1 immunohistochemistry on a large series of thoracic neuroendocrine and non-neuroendocrine tumors and compared its performance to synaptophysin, chromogranin, and CD56. INSM1 was positive in 94.9% of small cell lung carcinomas and 91.3% of large cell neuroendocrine carcinomas, compared with 74.4% and 78.3% with the combined panel of traditional markers. INSM1 also stained all (100%) of the atypical carcinoids, typical carcinoids and mediastinal paragangliomas, but only 3.3% of adenocarcinomas and 4.2% of squamous cell carcinomas. Overall, INSM1 demonstrated a sensitivity of 96.4% across all grades of thoracic neuroendocrine tumors, significantly more than the 87.4% using the panel of traditional markers (P=0.02). INSM1 is sufficiently sensitive and specific to serve as a standalone first-line marker of neuroendocrine differentiation. A more restrained approach to immunohistochemical analysis of small thoracic biopsies is appropriate given the expanding demand on this limited material for therapeutic biomarker analysis.

The impact of immunohistochemistry on the classification of lung tumors

INTRODUCTION

To highlight the role of immunohistochemistry to lung cancer classification on the basis of existing guidelines and future perspectives.

AREAS COVERED

Four orienting key-issues were structured according to an extensive review on the English literature: a) cancer subtyping; b) best biomarkers and rules to follow; c) negative and positive profiling; d) suggestions towards an evidence-based proposal for lung cancer subtyping. A sparing material approach based on a limited number of specific markers is highly desirable. It includes p40 for squamous cell carcinoma ('no p40, no squamous'), TTF1 for adenocarcinoma, synaptophysin for neuroendocrine tumors and vimentin for sarcomatoid carcinoma. A close relationship between genotype and phenotype also supports a diagnostic role for negative profiles. Expert commentary: Highly specific and sensitive IHC markers according to positive and negative diagnostic algorithms seem appropriate for individual patients' lung cancer subtyping.

Expression of PD-L1 Identifies a Subgroup of More Aggressive Non-Small Cell Carcinomas of the Lung

OBJECTIVES

In light of various trials showing impressive response rates when treating non-small cell lung cancer (NSCLC) patients with anti PD-1/PD-L1 antibodies, the currently equivocal role of PD-L1 expression in NSCLC is in need of further clarification.

METHODS

We therefore analyzed the expression of PD-L1 on 293 well-documented NSCLC cases and correlated the results with clinical, histopathological and immunohistochemical characteristics.

RESULTS

The expression of PD-L1 on NSCLC was a poor prognostic factor for patients with nodal-negative adenocarcinoma (ACA) and, independent of other covariates, in tumors with increased CD8+ tumor-infiltrating lymphocytes (TILs). Expression of PD-L1 was more commonly seen in ACA and in male patients with a past and current smoking history. Finally, PD-L1+ TILs were more often found in squamous and large cell carcinomas.

CONCLUSIONS

Should the expression of PD-L1 be on the verge of becoming an additional biomarker for routine diagnostics in NSCLC, our findings will provide important further insight and could contribute towards more effectively stratifying patients. These results may single out certain patient groups with a potential for increased benefit from anti PD-1/PD-L1 treatment strategies and should be considered in future trials.

[Pulmonary neuroendocrine tumors in the new WHO 2015 classification: Start of breaking new grounds?]

CLASSIFICATION

In the recently published 4th edition of the World Health Organization (WHO) classification of tumors of the lungs, pleura, thymus and heart, all neuroendocrine tumors of the lungs (pNET) are presented for the first time in one single chapter following adenocarcinoma and squamous cell carcinoma and before large cell carcinoma. In this classification, high grade small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC) are differentiated from intermediate grade atypical carcinoids (AC) and low grade typical carcinoids as well as from preinvasive lesions (DIPNECH). In the 3rd WHO classification from 2004, which dealt with resection specimens, SCLC and carcinoids each had a separate chapter and LCNEC was previously listed in the chapter on large cell carcinoma of the lungs. The new WHO classification is for the first time also applicable to lung biopsies.

DIAGNOSTICS

Normally, common features of all pNET are a neuroendocrine morphology (as far as detectable in small biopsies) and expression of the neuroendocrine (NE) markers (chromogranin A, synaptophysin and CD56/NCAM). An immunohistochemical positive staining of at least one NE marker was already recommended in the 3rd edition of the WHO classification (2004) only for LCNEC. Differentiating features are a small or large cell cytomorphology/histomorphology, nuclear criteria and the mitotic rate (for SCLC >10 with a median of 80, for LCNEC >10 median 70, for AC 2 - 10, for TC < 2 each per 2 mm(2)). Tumor cell necrosis usually occurs in SCLC and LCNEC, partially in AC and not in TC. The guideline Ki67 proliferation rates are given for the first time in the new WHO classification for SCLC as 50-100 %, for LCNEC 40-80 %, for AC up to 20 % and for TC up to 5 %.

MOLECULAR PATHOLOGY

Molecular alterations occur in SCLC and LCNEC in large numbers and are very variable in quality. In AC and TC they occur much less frequently and are relatively similar.

CONCLUSION

The direct comparison of all pNET in one chapter facilitates the differential diagnostics of these tumors, provides a better transparency especially of LCNEC and allows a further comprehensive development of the clinical practical and scientific evaluation of pNET. Although a separate terminology of pNET is maintained for the lungs, a careful approach towards the gastroentero-pancreatic NET (gepNET) can be observed.

Expression of the CXCR4 ligand SDF-1/CXCL12 is prognostically important for adenocarcinoma and large cell carcinoma of the lung

The SDF-1/CXCR4 axis is associated with tumor progression and has been reported as a prognostic parameter, although with conflicting data for non-small cell lung cancer (NSCLC). This study examines a large cohort of clinically and pathologically well-characterized NSCLC patients and includes the activated form of CXCR4 (pCXCR4), which has not been studied in this context so far. SDF-1, CXCR4, and pCXCR4 were assessed immunohistochemically in 371 surgically resected NSCLC using a standardized tissue microarray platform. Extensive clinical and pathological data and a postoperative follow-up period of 17 years enabled detailed correlations. CXCR4 and pCXCR4 were frequently expressed on squamous cell carcinoma. Membranous expression of SDF-1 was a marker of poor prognosis and proved to be an independent prognostic parameter for the entire cohort and for patients with adenocarcinoma (ACA) and large cell carcinoma (LCC). Targeted cancer therapies blocking SDF-1/CXCR4 interaction already exist, and our data suggest that expression of SDF-1, especially on poorer prognosis subgroups of LCC and ACA, indicates patients that might benefit more than others. This should be taken into account when assessing the effectiveness of such targeted approaches for NSCLC patients and could lead to important implications.

Reevaluation and reclassification of resected lung carcinomas originally diagnosed as squamous cell carcinoma using immunohistochemical analysis

Currently, non-small cell lung carcinomas are primarily classified by light microscopy. However, recent studies have shown that poorly differentiated tumors are more accurately classified by immunohistochemistry. In this study, we investigated the use of immunohistochemical analysis in reclassifying lung carcinomas that were originally diagnosed as squamous cell carcinoma. Tumor slides and blocks were available for histologic evaluation, and tissue microarrays were constructed from 480 patients with resected lung carcinomas originally diagnosed as squamous cell carcinoma between 1999 and 2009. Immunohistochemical analyses for p40, p63, thyroid transcription factor-1 (TTF-1; clones SPT24 and 8G7G3/1), napsin A, chromogranin A, synaptophysin, and CD56 were performed. Staining intensity (weak, moderate, or strong) and distribution (focal or diffuse) were also recorded. Of all, 449 (93.5%) patients were confirmed as having squamous cell carcinomas; the cases were mostly diffusely positive for p40 and negative for TTF-1 (8G7G3/1). Twenty cases (4.2%) were reclassified as adenocarcinoma, as they were positive for TTF-1 (8G7G3/1 or SPT24) with either no or focal p40 expression, and all of them were poorly differentiated with squamoid morphology. In addition, 1 case was reclassified as adenosquamous carcinoma, 4 cases as large cell carcinoma, 4 cases as large cell neuroendocrine carcinoma, and 2 cases as small cell carcinoma. In poorly differentiated non-small cell lung carcinomas, an accurate distinction between squamous cell carcinoma and adenocarcinoma cannot be reliably determined by morphology alone and requires immunohistochemical analysis, even in resected specimens. Our findings suggest that TTF-1 8G7G3/1 may be better suited as the primary antibody in differentiating adenocarcinoma from squamous cell carcinoma.

[Neuroendocrine tumors of the lungs. From small cell lung carcinoma to diffuse idiopathic pulmonary neuroendocrine cell hyperplasia]

The new World Health Organization (WHO) classification announced for 2015 will for the first time present all neuroendocrine tumors (NET) of the lungs in one single section. In this classification high grade small cell lung carcinoma (SCLC) and large cell neuroendocrine carcinoma (LCNEC) will be discriminated from intermediate grade atypical carcinoid (AC) and low grade typical carcinoid as well as from the preinvasive lesion diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH). The LCNEC was previously listed under the section of large cell carcinomas. The LCNEC could previously be diagnosed according to the current WHO classification from 2004 which is designed for resection specimens. According to this the main diagnostic criteria are a neuroendocrine growth pattern which can be difficult or impossible to detect in biopsy material, non-small cell cytological features, more than 10 mitoses per 2 mm(2) (mean 70-80 per 2 mm(2)), tumor cell necrosis, and an immunohistochemical positivity for at least one neuroendocrine marker other than neuron-specific enolase (NSE). The presentation of all neuroendocrine tumors of the lungs in one section allows a more direct comparison and a better differential diagnostic discrimination of the different entities.

NSCLC without Antineoplastic Treatment: Incidence, Characteristics, and Outcome as Outlined in the TYROL Study

BACKGROUND

The treatment of non-small cell lung cancer (NSCLC) has become more and more individualized with the availability of potent and less toxic therapies. However, there are still patients who do not receive antineoplastic treatment. The aim of this study was to investigate the incidence of 'no treatment', its reasons, and the outcome of untreated NSCLC patients in recent years.

PATIENTS AND METHODS

Medical files of 1,256 consecutive NSCLC patients diagnosed between 2001 and 2009 at the Medical University of Innsbruck and affiliated hospitals were retrospectively analyzed.

RESULTS

In 66 of the 1,256 patients (5.3%), the absence of antineoplastic treatment could be ascertained. The median age was 72.1 years, and 42 patients (63.3%) were males. The majority of patients presented with stage IV (n=45; 68.2%). Treatment was omitted due to physical deterioration in 41 patients (62.1%), and 25 patients (37.9%) refused any treatment. The median overall survival of the untreated patients was 3.1 months (refusal: 9.7 months; physical deterioration: 2.1 months).

CONCLUSION

This study provides information on the incidence of NSCLC patients without antineoplastic treatment and gives a detailed description of the characteristics and comorbidities. These data might help clinicians in the survival estimations of their NSCLC patients in scenarios like therapy refusal or poor physical condition.

Large cell carcinoma of the lung: a tumor in search of an author. A clinically oriented critical reappraisal

Large cell carcinoma (LCC) is a merely descriptive term indicating a subtype of lung cancer with no specific features of small-cell lung cancer (SCLC), adenocarcinoma (ADC) or squamous cell carcinoma (SQC). This diagnosis is allowed on surgical specimens only, whereas its counterpart in biopsy/cytology samples is non-small-cell lung carcinoma (NSCLC), not otherwise specified (NOS). Although these two terms do not fulfill the same concept, they can be interchangeable synonyms at the clinical level, reflecting, in different ways, the inability to define a specific subtype. Immunohistochemistry (IHC), next generation sequencing (NGS) analysis and, historically, electron microscopy have been unveiling diverse cell differentiation lineages in LCC, resulting in LCC-favor ADC, LCC-favor SQC and LCC-favor large-cell neuroendocrine carcinoma (LCNEC), the latter hopefully to be included into the neuroendocrine tumor (NET) group in the future. Paradoxically, however, the interpretation issues of LCC/NSCLC-NOS are not diminishing, but even increasing albeight an accurate diagnosis is oncologically required and crucial. Also, rare LCC/NSCLC-NOS cases exhibiting null/unclear phenotype, are difficult to classify, and this terminology could be maintained for the sake of classification (basically these tumors are serendipitous ADC, as also confirmed by the lack of p40). In this review article, seven relevant issues to LCC have been addressed by using a question-answer methodology, with final key points discussing major interpretation issues. In conclusion, most LCC/NSCLC-NOS may be eventually re-classified and addressed by exploiting IHC and/or molecular testing to satisfy the criteria of precision medicine (the right drug, to the right patient, at the right time).

Predictors of survival after operation among patients with large cell neuroendocrine carcinoma of the lung

BACKGROUND

Large cell neuroendocrine carcinoma (LCNEC) represents a rare entity in non-small cell lung cancer, with only partially understood biology and poor survival. A diagnosis is difficult to obtain on the basis of small biopsy specimens, but surgical procedures may be indicated in only a small fraction of patients. The aim of this study was to assess the clinical and immunohistochemical features of patients with LCNEC to identify predictors of outcome and long-term survival.

METHODS

The clinical and pathologic data of 57 surgical patients with LCNEC between March 2003 and December 2012 were retrospectively reviewed. The tumor specimens were examined for expression of neuronal specific enolase, synaptophysin, CD 56, chromogranin-A, and the somatostatin receptor by immunohistochemistry. Statistical analysis was performed to determine significant predictors for overall survival and recurrence-free survival.

RESULTS

Fifty-seven patients (41 men, 16 women) underwent thoracic operations with curative intent. Complete resection was achieved in 91% of cases. The results of staining for CD56, synaptophysin, neuronal specific enolase, chromogranin-A, and somatostatin were positive in 86%, 81%, 68%, 61%, and 21%, respectively. Recurrence occurred in 28 patients (49%). Overall survival and recurrence-free survival were 50% and 45%, respectively, after 3 years. Advanced nodal status (N1, p < 0.025; N2, p < 0.02) and simultaneous expression of CD56 and chromogranin-A (p < 0.04) were significantly associated with poorer outcome.

CONCLUSIONS

LCNEC is a rare neuroendocrine pulmonary malignancy that is associated with poor prognosis and high recurrence rates. Surgical treatment can achieve satisfactory results in selected cases. Neuroendocrine marker profiles may predict prognosis and may influence the decision for adjuvant therapy or follow-up intervals.

Longitudinal analysis of 2293 NSCLC patients: a comprehensive study from the TYROL registry

INTRODUCTION

The aim of this study was to describe a large consecutive cohort of non-small cell lung cancer (NSCLC) patients treated in daily routine within the last 25 years. An extensive list of general baseline characteristics (comorbidities, laboratory values, symptoms, performance state), NSCLC related factors (stage, histology), treatment related parameters (approach, applied therapies) and outcome (PFS, RFS, OS, perspective of decades) were analyzed in detail.

PATIENTS AND METHODS

Medical files of 2293 consecutive NSCLC patients diagnosed between 1989 and 2009 at the Medical University of Innsbruck and affiliated hospitals were retrospectively analyzed. Patients were documented within our institution's comprehensive lung cancer project "Twenty-Year Retrospective of Lung Cancer (TYROL study)".

RESULTS

Mean age at diagnosis was 64.1 years and 1611 patients (70.3%) were male. Most patients were diagnosed in stage IV (37.9%). The most frequent comorbidities present at diagnosis were cardiovascular disease (62.1%) and COPD (62.0%). The most common symptoms at diagnosis were coughing (54.7%) and dyspnea (45.3%). Of all 2293 patients 1981 (86.4%) received adequate antineoplastic treatment. In total 874 patients were radically operated, 119 received radiotherapy/radio-chemotherapy and the majority of patients (n=1278) were treated in palliative intent. A 2nd, 3rd, 4th and 5th-line palliative therapy was administered to 612, 278, 102, and 36 patients. Median OS, RFS and PFS were 16.4 months, 86.4 months and 5.1 months, respectively. A multitude of factors was associated with all three outcome variables. Of note, outcome has improved stepwise in the recent decade based on increased response rates leading to prolonged OS.

CONCLUSION

This work incorporates most clinical aspects relevant in the treatment of NSCLC and beyond. Therefore, this comprehensive analysis provides a definite benchmark for prognostication and epidemiology of NSCLC in a Western European society.

Neuroendocrine differentiation in acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitor

Background

Small cell lung cancer (SCLC) transformation during epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment in lung cancer has been suggested as one of possible resistance mechanisms.

Methods

We evaluated whether SCLC transformation or neuroendocrine (NE) differentiation can be found in the cell line model. In addition, we also investigated its effect on responses to conventional chemotherapeutic drugs of the SCLC treatment.

Results

Resistant cell lines to various kinds of EGFR-TKIs such as gefitinib, erlotinib, CL-387,785 and ZD6474 with A549, PC-9 and HCC827 lung adenocarcinoma cell lines were established. Among them, two resistant cell lines, A549/GR (resistant to gefitinib) and PC-9/ZDR (resistant to ZD6474) showed increased expressions of CD56 while increased synaptophysin, Rb, p16 and poly(ADP-ribose) polymerase were found only in A549/GR in western blotting, suggesting that NE differentiation occurred in A549/GR. A549/GR cells were more sensitive to etoposide and cisplatin, chemotherapeutic drugs for SCLC, compared to parental cells. Treatment with cAMP and IBMX induced synaptophysin and chromogranin A expression in A549 cells, which also made them more sensitive to etoposide and cisplatin than parental cells. Furthermore, we found a tissue sample from a patient which showed increased expressions of CD56 and synaptophysin after development of resistance to erlotinib.

Conclusion

NE differentiation can occur during acquisition of resistance to EGFR-TKI, leading to increased chemosensitivity.

Alterations in gene expression of proprotein convertases in human lung cancer have a limited number of scenarios

Proprotein convertases (PCs) is a protein family which includes nine highly specific subtilisin-like serine endopeptidases in mammals. The system of PCs is involved in carcinogenesis and levels of PC mRNAs alter in cancer, which suggests expression status of PCs as a possible marker for cancer typing and prognosis. The goal of this work was to assess the information value of expression profiling of PC genes. Quantitative polymerase chain reaction was used for the first time to analyze mRNA levels of all PC genes as well as matrix metalloproteinase genes MMP2 and MMP14, which are substrates of PCs, in 30 matched pairs of samples of human lung cancer tumor and adjacent tissues without pathology. Significant changes in the expression of PCs have been revealed in tumor tissues: increased FURIN mRNA level (p<0.00005) and decreased mRNA levels of PCSK2 (p<0.007), PCSK5 (p<0.0002), PCSK7 (p<0.002), PCSK9 (p<0.00008), and MBTPS1 (p<0.00004) as well as a tendency to increase in the level of PCSK1 mRNA. Four distinct groups of samples have been identified by cluster analysis of the expression patterns of PC genes in tumor vs. normal tissue. Three of these groups covering 80% of samples feature a strong elevation in the expression of a single gene in cancer: FURIN, PCSK1, or PCSK6. Thus, the changes in the expression of PC genes have a limited number of scenarios, which may reflect different pathways of tumor development and cryptic features of tumors. This finding allows to consider the mRNAs of PC genes as potentially important tumor markers.

Low-dose zoledronic acid reduces spinal cord metastasis in pulmonary adenocarcinoma with neuroendocrine differentiation

Zoledronic acid (ZOL), a nitrogen-containing compound, is effective in the treatment of skeletal disorders, but its long-term use in high doses gives rise to complications such as osteonecrosis. We aimed to investigate the effect of low-dose ZOL on the expression of the neural cell adhesion molecule (NCAM), which may be correlated with tumor growth and spinal cord metastasis in lung adenocarcinoma with neuroendocrine differentiation. First, we used the small hairpin RNA technique to directly knock down NCAM expression in cells of a murine lung adenocarcinoma line, line 1 cells, and found that the tumor cells generated showed lower invasive capacity, slower tumor growth, and lesser tendency for spinal cord metastasis than control cells. Further, ZOL decreased NCAM expression and invasiveness in line 1 tumor cells in vitro. Line 1/lacZ cells, a stable clone tagged with the lacZ gene, were introduced into mice, followed by ZOL treatment (1 μg/kg/weekly). Low-dose ZOL significantly reduced spinal cord metastasis probably through reduced NCAM expression in vivo. These findings indicated that NCAM is involved in tumor growth and spinal cord metastasis of lung adenocarcinoma with neuroendocrine differentiation. Treatment with low-dose ZOL can reduce NCAM expression that may contribute toward reduced spinal cord metastasis, suggesting that NCAM is an alternative therapeutic target and that the low-dose ZOL treatment protocol is a reasonable approach for its treatment.

Diagnosis of lung cancer in small biopsies and cytology: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification

The new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society lung adenocarcinoma classification provides, for the first time, standardized terminology for lung cancer diagnosis in small biopsies and cytology; this was not primarily addressed by previous World Health Organization classifications. Until recently there have been no therapeutic implications to further classification of NSCLC, so little attention has been given to the distinction of adenocarcinoma and squamous cell carcinoma in small tissue samples. This situation has changed dramatically in recent years with the discovery of several therapeutic options that are available only to patients with adenocarcinoma or NSCLC, not otherwise specified, rather than squamous cell carcinoma. This includes recommendation for use of special stains as an aid to diagnosis, particularly in the setting of poorly differentiated tumors that do not show clear differentiation by routine light microscopy. A limited diagnostic workup is recommended to preserve as much tissue for molecular testing as possible. Most tumors can be classified using a single adenocarcinoma marker (eg, thyroid transcription factor 1 or mucin) and a single squamous marker (eg, p40 or p63). Carcinomas lacking clear differentiation by morphology and special stains are classified as NSCLC, not otherwise specified. Not otherwise specified carcinomas that stain with adenocarcinoma markers are classified as NSCLC, favor adenocarcinoma, and tumors that stain only with squamous markers are classified as NSCLC, favor squamous cell carcinoma. The need for every institution to develop a multidisciplinary tissue management strategy to obtain these small specimens and process them, not only for diagnosis but also for molecular testing and evaluation of markers of resistance to therapy, is emphasized.

Tissue-sparing application of the newly proposed IASLC/ATS/ERS classification of adenocarcinoma of the lung shows practical diagnostic and prognostic impact

The histologic subtype of non-small cell lung cancer (NSCLC) determines treatment strategies and the need for genetic analyses. Since most NSCLC are diagnosed on small biopsy or cytologic specimens, an accurate but tissue-sparing approach is necessary. To date, consensus for a general diagnostic algorithm is lacking. To test the diagnostic and clinical relevance of the recently published multidisciplinary guidelines by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society, we examined 371 surgically resected NSCLCs brought into tissue microarray format. The antibody panel thyroid transcription factor-1 (TTF-1), p63, cytokeratin (CK)5/6, and CK7 is diagnostic for most cases (>94%). Faint/focal staining for CK7 is negligible for classificatory purposes. Grading adenocarcinomas according to histologic architecture is prognostically significant (median overall survival for well/moderate differentiation, 72.5 months; for poor differentiation, 38.5 months; P = .019). Double stains combining the aforementioned nuclear and membranous markers are highly diagnostic for NSCLC, conserving tumor tissue for subsequent analyses.

A comprehensive analysis of p16 expression, gene status, and promoter hypermethylation in surgically resected non-small cell lung carcinomas

INTRODUCTION

The role of p16 is gaining importance in non-small cell lung cancer (NSCLC) because of epigenetic therapy options. Further insight into the significance of protein expression, gene status and promoter methylation is needed and has the potential to optimize existing treatment strategies.

METHODS

This population-based study analyzes p16 in 383 surgically resected non-small cell lung carcinomas brought into a standardized tissue microarray platform. Immunohistochemistry and fluorescence in situ hybridization were performed. For selected cases, p16 promoter hypermethylation was assessed by a pyrosequencing assay. Extensive clinical data and a postoperative follow-up period of 15 years enabled detailed correlations.

RESULTS

Loss of p16 expression is a common event in NSCLC (232/365, 64%), especially in squamous cell carcinomas (97/115, 84%) in contrast to adenocarcinomas (93/186, 50%). Loss of p16 expression was associated with poorer survival time for the entire cohort and for certain subgroups including men, age younger than 65 years, smokers, early tumor stage, adenocarcinoma, and large-cell carcinoma. Promoter hypermethylation was absent for cases expressing p16 but was commonly observed when (heterozygous) p16 gene deletions were present and in cases negative for p16.

CONCLUSION

Our comprehensive data would be compatible with a two-step process leading to loss of p16 expression in NSCLC. Hypermethylation of the promoter region may represent an early event, followed by heterozygous deletion of the p16 locus. Because of the possibility of detection of hypermethylated gene regions, these data may lead to the identification of specific patient subgroups more likely to benefit from upcoming demethylating treatment strategies.

[Neuroendocrine differentiation is not a malignant index of non-small cell lung cancer]

BACKGROUND

A debate has been ongoing whether non-small cell lung cancer(NSCLC) with neuroendocrine(NE) differentiation likely indicates malignant behavior, poor prognosis, and sensitivity to chemotherapy. In response to this issue, we retrospectively investigated NE differentiation in NSCLC patients who underwent anatomical pulmonary surgery.

METHODS

A total of 274 patients who met the inclusion criteria through January 2000 to December 2008 were enrolled in this study because they had the detailed material and enough paraffin tumor samples for tissue microarray. The recommended antibody panel consisted of CgA, Syn, NCAM, Leu-7, PGP9.5, and MAP-2. We also counted Ki-67 in the tissues to present the nuclear proliferation index. The Kaplan-Meier estimator and the Cox proportional hazard model multivariate analysis were applied to observe the relationship between NE differentiation and postoperative survival of the patients.

RESULTS

The Cox analysis of different NE score combinations on the prognosis of NSCLC after surgical treatment did not reach statistical significance (score 1, score 2, and score≥3 vs score 0, P=0.527; score 0 vs score ≥1, P=0.791; score<2 vs score≥2, P=0.163; score<3 vs score≥3, P=0.293). The Kaplan-Meier estimator did not give significant difference in the survival of NE score combinations in each pTNM layer. In the perioperative chemotherapy group, we also did not find a positive correlation for the survival analysis of NE score combinations (score 1, score 2, and score≥3 vs score 0, P=0.692; score 0 vs score≥1, P=0.922; score<2 vs score ≥2, P=0.264; score<3 vs score≥3, P=0.484).

CONCLUSIONS

The NE differentiation of NSCLC reflects some structure and functional characteristics of NELT, although it cannot be used as an independent factor of biological behavior and survival for NSCLC patients who underwent surgery in our group.

High transforming growth factor β expression represents an important prognostic parameter for surgically resected non-small cell lung cancer

The tumor microenvironment comprises various cellular components and associated subcellular molecules with antitumor and protumor effects. Because respective targeted treatment strategies are arising, it is important to characterize the exact role of these parameters. This study provides a comprehensive analysis of key immunologic factors in the tumor microenvironment of 383 surgically resected non-small cell lung cancer specimens. CD4, CD8, forkhead box protein P3, transforming growth factor β, Casitas B-cell lymphoma-b, programed death 1, T-cell-restricted intracellular antigen 1, granzyme B, mast cell tryptase, and stromal cell-derived factor 1 were analyzed by immunohistochemistry using a standardized tissue microarray platform. Extensive clinical data enabled detailed clinicopathologic correlations over a postoperative follow-up period of 15 years. Among the immunologic variables focused on, transforming growth factor β expression was the only prognostically relevant factor. Transforming growth factor β was more frequently expressed in adenocarcinoma as compared with other histologic subtypes. Expression of transforming growth factor β in tumor-infiltrating lymphocytes or in tumor cells was associated with significantly reduced postoperative survival time especially in patients with squamous cell carcinoma (P = .035 and P = .046, respectively). In these patients, the amount of transforming growth factor β-positive tumor-infiltrating lymphocytes represented the only independent immunologic parameter with prognostic significance by multivariat analysis (P = .021; hazard ratio, 2.602; 95% confidence interval, 1.159-5.844). These results should help to identify patients who are most suitable for therapeutic strategies aiming to block the transforming growth factor β signaling pathway.

Diagnostic issues with cytopathologic interpretation of lung neoplasms displaying high-grade basaloid or neuroendocrine morphology

Basaloid squamous cell carcinoma (BSQCC) and high-grade neuroendocrine carcinomas (HGNEC) including small cell carcinoma (SMCC) and large cell neuroendocrine carcinoma (LCNEC) can be difficult to differentiate on lung cytology. This problem is particularly true in scant specimens where immunoperoxidase stains cannot be adequately performed. Sixty-six cases of BSQCC, LCNEC, and SMCC (22 cases of each) on lung or mediastinal cytology were retrospectively reviewed from the cytopathology archives of two hospitals. Common cytomorphologic characteristics were; hypercellularity, small to intermediate round blue (hyperchromatic) cells, lack of prominent nucleoli, lack of three dimensional architecture, karyorrhexis/necrosis, mitoses, naked nuclei, nuclear crush artifact, and nuclear molding. Distinctive features included: larger cell size with pleomorphism, more cohesive architecture, syncytial aggregation, slightly coarser chromatin texture, rare keratinized malignant cells, and a granular smear background seen more often in BSQCC as opposed to HGNEC. Larger cells with prominent nucleoli and more cytoplasm with focal rosette formation were helpful in distinguishing LCNEC from SMCC and BSQCC. Finally, SMCC displayed uniform small cells with extensive necrosis, and higher mitotic rate. Immunoperoxidase (IPOX) staining using p63, CK5, 6, neuroendocrine markers (chromogranin, synaptophysin and CD56) and TTF-1 were helpful. BSQCC showed p63 expression and was mostly negative for neuroendocrine markers and TTF-1. HGNEC showed immunoreactivity for neuroendocrine markers with variable immunoreactivity for TTF-1. BSQCC, SMCC, and LCNEC share overlapping cytomorphologic features and can be difficult to differentiate on limited cytology specimens. Careful consideration to subtle but definite cytomorphologic clues and attention to selective IPOX stains can lead to a definitive diagnosis.