Neuroendocrine differentiation in non-small cell lung cancer and its relation to prognosis and therapy

A platform-independent AI tumor lineage and site (ATLAS) classifier

Histopathologic diagnosis and classification of cancer plays a critical role in guiding treatment. Advances in next-generation sequencing have ushered in new complementary molecular frameworks. However, existing approaches do not independently assess both site-of-origin (e.g. prostate) and lineage (e.g. adenocarcinoma) and have minimal validation in metastatic disease, where classification is more difficult. Utilizing gradient-boosted machine learning, we developed ATLAS, a pair of separate AI Tumor Lineage and Site-of-origin models from RNA expression data on 8249 tumor samples. We assessed performance independently in 10,376 total tumor samples, including 1490 metastatic samples, achieving an accuracy of 91.4% for cancer site-of-origin and 97.1% for cancer lineage. High confidence predictions (encompassing the majority of cases) were accurate 98-99% of the time in both localized and remarkably even in metastatic samples. We also identified emergent properties of our lineage scores for tumor types on which the model was never trained (zero-shot learning). Adenocarcinoma/sarcoma lineage scores differentiated epithelioid from biphasic/sarcomatoid mesothelioma. Also, predicted lineage de-differentiation identified neuroendocrine/small cell tumors and was associated with poor outcomes across tumor types. Our platform-independent single-sample approach can be easily translated to existing RNA-seq platforms. ATLAS can complement and guide traditional histopathologic assessment in challenging situations and tumors of unknown primary.

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.

Depiction of neuroendocrine features associated with immunotherapy response using a novel one-class predictor in lung adenocarcinoma

BACKGROUND

Tumours with no evidence of neuroendocrine transformation histologically but harbouring neuroendocrine features are collectively referred to as non-small cell lung cancer (NSCLC) with neuroendocrine differentiation (NED). Investigating the mechanisms underlying NED is conducive to designing appropriate treatment options for NSCLC patients.

METHODS

In the present study, we integrated multiple lung cancer datasets to identify neuroendocrine features using a one-class logistic regression (OCLR) machine learning algorithm trained on small cell lung cancer (SCLC) cells, a pulmonary neuroendocrine cell type, based on the transcriptome of NSCLC and named the NED index (NEDI). Single-sample gene set enrichment analysis, pathway enrichment analysis, ESTIMATE algorithm analysis, and unsupervised subclass mapping (SubMap) were performed to assess the altered pathways and immune characteristics of lung cancer samples with different NEDI values.

RESULTS

We developed and validated a novel one-class predictor based on the expression values of 13,279 mRNAs to quantitatively evaluate neuroendocrine features in NSCLC. We observed that a higher NEDI correlated with better prognosis in patients with LUAD. In addition, we observed that a higher NEDI was significantly associated with reduced immune cell infiltration and immune effector molecule expression. Furthermore, we found that etoposide-based chemotherapy might be more effective in the treatment of LUAD with high NEDI values. Moreover, we noted that tumours with low NEDI values had better responses to immunotherapy than those with high NEDI values.

CONCLUSIONS

Our findings improve the understanding of NED and provide a useful strategy for applying NEDI-based risk stratification to guide decision-making in the treatment of LUAD.

PRMT5 promotes chemotherapy-induced neuroendocrine differentiation in NSCLC

BACKGROUND

In response to therapeutic treatments, cancer cells can exhibit a variety of resistance phenotypes including neuroendocrine differentiation (NED). NED is a process by which cancer cells can transdifferentiate into neuroendocrine-like cells in response to treatments, and is now widely accepted as a key mechanism of acquired therapy resistance. Recent clinical evidence has suggested that non-small cell lung cancer (NSCLC) can also transform into small cell lung cancer (SCLC) in patients treated with EGFR inhibitors. However, whether chemotherapy induces NED to confer therapy resistance in NSCLC remains unknown.

METHODS

We evaluated whether NSCLC cells can undergo NED in response to chemotherapeutic agents etoposide and cisplatin. By Knock-down of PRMT5 or pharmacological inhibition of PRMT5 to identify its role in the NED process.

RESULTS

We observed that both etoposide and cisplatin can induce NED in multiple NSCLC cell lines. Mechanistically, we identified protein arginine methyltransferase 5 (PRMT5) as a critical mediator of chemotherapy-induced NED. Significantly, the knock-down of PRMT5 or pharmacological inhibition of PRMT5 suppressed the induction of NED and increased the sensitivity to chemotherapy.

CONCLUSION

Taken together, our results suggest that targeting PRMT5 may be explored as a chemosensitization approach by inhibiting chemotherapy-induced NED.

Targeting programmed cell death protein 1 (PD-1) for treatment of non-small-cell lung carcinoma (NSCLC); the recent advances

The immune system uses various immune checkpoint axes to adjust responses, support homeostasis, and deter self-reactivity and autoimmunity. Nevertheless, non-small-cell lung carcinoma (NSCLC) can use protective mechanisms to facilitate immune evasion, which leads to potentiated cancer survival and proliferation. In this light, many blocking anti-bodies have been developed to negatively regulate checkpoint molecules, in particular, programmed cell death protein 1 (PD-1) / PD-ligand 1 (L1), and bypass these immune suppressive mechanisms. Meanwhile, anti-PD-1 anti-bodies such as nivolumab, pembrolizumab, cemiplimab, and sintilimab have shown excellent competence in successfully inspiring immune responses versus NSCLC. Accordingly, the United States Food and Drug Administration (FDA) has recently approved nivolumab (alone or in combination with ipilimumab) and pembrolizumab (alone or in combination with chemotherapy) as first-line treatment for advanced NSCLC patients. However, PD-1 blockade monotherapy remains inefficient in more than 60% of NSCLC patients, and many patients don't respond or acquire resistance to this modality. Also, toxicities related to anti-PD-1 anti-body have been progressively identified in clinical trials and oncology practice. Herein, we will outline the clinical benefits of PD-1 blockade therapy alone or in combination with other treatments (e.g., chemotherapy, radiotherapy, anti-angiogenic therapy) in NSCLC patients. Moreover, we will take a glimpse into the recently identified predictive biomarkers to determine patients most likely to suffer serious adverse events to decrease untoward toxicity risk and diminish treatment costs.

Lung adenocarcinoma with neuroendocrine differentiation: Molecular markers testing and treatment outcomes

BACKGROUND

Among the histologic types of lung cancer, adenocarcinoma is the most common. Moreover, lung adenocarcinoma with neuroendocrine differentiation (LANED) is a rare histologic character. So far, the clinical significance remains unclear.

MATERIAL AND METHODS

We searched for the patients diagnosed with LANED from the electronic pathology database between January 2000 and June 2020 in a tertiary hospital. The tumor specimens were reviewed by a pathologist to confirm the diagnosis. EGFR mutation, ALK translocation, as well as programmed death ligand 1 (PD-L1) and rearranged during transfection (RET) expression were tested in the specimens of LANED. The clinical data were also collected and analyzed.

RESULTS

A total of 10 patients diagnosed with LANED were included. Most were male (80%) and ever smokers (70%). The median age was 71.5 years old. At diagnosis, most had tumors harboring no EGFR mutation (70%), negative ALK translocation (88.9%), and without PD-L1 expression (90%). All specimens tested by immunohistochemical staining for RET expression (n = 9) showed positive results. Among the 10 patients, five underwent operation (stage I, n = 4; stage II, n = 1). The patient with stage II disease had recurrence 11 months later. For patients with advanced stages (stage III, n = 1; stage IV, n = 4), the treatment modalities varied and the overall survival ranged from 11.0 to 46.7 months.

CONCLUSION

LANED might be associated with a high proportion of RET expression, whereas EGFR mutation, ALK alteration, and PD-L1 expression were uncommon. Further large-scale prospective studies on molecular testing profile and clinical significance of LANED are warranted.

Analysis of neuroendocrine clones in NSCLCs using an immuno-guided laser-capture microdissection-based approach

Clonal evolution and lineage plasticity are key contributors to tumor heterogeneity and response to treatment in cancer. However, capturing signal transduction events in coexisting clones remains challenging from a technical perspective. In this study, we developed and tested a signal-transduction-based workflow to isolate and profile coexisting clones within a complex cellular system like non-small cell lung cancers (NSCLCs). Cooccurring clones were isolated under immunohistochemical guidance using laser-capture microdissection, and cell signaling activation portraits were measured using the reverse-phase protein microarray. To increase the translational potential of this work and capture druggable vulnerabilities within different clones, we measured expression/activation of a panel of key drug targets and downstream substrates of FDA-approved or investigational agents. We isolated intermixed clones, including poorly represented ones (<5% of cells), within the tumor microecology and identified molecular characteristics uniquely attributable to cancer cells that undergo lineage plasticity and neuroendocrine transdifferentiation in NSCLCs.

SOX11 is a sensitive and specific marker for pulmonary high-grade neuroendocrine tumors

BACKGROUND

Synaptophysin (SYN), chromogranin A (CGA), CD56 and insulinoma-associated protein 1 (INSM1) are proposed neuroendocrine (NE) markers used for diagnosis of pulmonary NE tumors. These NE markers have been identified in subsets of non-NE tumors requiring differential diagnosis, thus we sought to explore new NE markers.

METHODS

We evaluated the immunohistochemical expression of SOX11, a transcription factor involved in neurogenesis, in pulmonary NE tumors and large cell carcinomas (LCCs).

RESULTS

We found that SOX11 showed a sensitivity similar to INSM1 and CGA, and less than SYN and CD56 in small cell lung carcinomas (SCLCs) and large cell neuroendocrine carcinomas (LCNECs). While SOX11 is more specific than the other four markers for diagnosis of high-grade neuroendocrine carcinomas (HG-NECs) because 1) None of LCCs (0/63), the most challenging non-NE tumor type for differential diagnosis due to overlapped morphology with LCNECs displayed SOX11 positivity. While expression of at least one of SYN, CGA, CD56 or INSM1 was identified in approximately 60% (18/30) of LCCs. 2) SOX11 was only expressed in 1 of 37 carcinoid tumors in contrast to diffuse expression of SYN, CGA, CD56 and INSM1. In HG-NECs, we noticed that SOX11 was a good complementary marker for SCLC diagnosis as it was positive in 7 of 18 SYN^-/CGA^-/CD56^- SCLCs and 3 of 8 SYN^-/CGA^-/CD56^-/INSM1^- SCLCs, and SOX11 positivity in 4 of 6 SYN^-/CGA^-/CD56^- cases previously diagnosed as LCCs with NE morphology provides additional evidence of NE differentiation for reclassification into LCNECs, which was further confirmed by electromicroscopical identification of neurosecretory granules. We also found SOX11 expression cannot predict the prognosis in patients with HG-NECs.

CONCLUSIONS

Therefore, SOX11 is a useful complementary transcriptional NE marker for diagnosis and differential diagnosis of SCLC and LCNEC.

Insulinoma-associated Protein 1 (INSM1) in Thoracic Tumors is Less Sensitive but More Specific Compared With Synaptophysin, Chromogranin A, and CD56

OBJECTIVE

Recognition of neuroendocrine differentiation is important for tumor classification and treatment stratification. To detect and confirm neuroendocrine differentiation, a combination of morphology and immunohistochemistry is often required. In this regard, synaptophysin, chromogranin A, and CD56 are established immunohistochemical markers. Insulinoma-associated protein 1 (INSM1) has been suggested as a novel stand-alone marker with the potential to replace the current standard panel. In this study, we compared the sensitivity and specificity of INSM1 and established markers.

MATERIALS AND METHODS

A cohort of 493 lung tumors including 112 typical, 39 atypical carcinoids, 77 large cell neuroendocrine carcinomas, 144 small cell lung cancers, 30 thoracic paragangliomas, 47 adenocarcinomas, and 44 squamous cell carcinomas were selected and tissue microarrays were constructed. Synaptophysin, chromogranin A, CD56, and INSM1 were stained on all cases and evaluated manually as well as with an analysis software. Positivity was defined as ≥1% stained tumor cells in at least 1 of 2 cores per patient.

RESULTS

INSM1 was positive in 305 of 402 tumors with expected neuroendocrine differentiation (typical and atypical carcinoids, large cell neuroendocrine carcinomas, small cell lung cancers, and paraganglioma; sensitivity: 76%). INSM1 was negative in all but 1 of 91 analyzed non-neuroendocrine tumors (adenocarcinomas, squamous cell carcinomas; specificity: 99%). All conventional markers, as well as their combination, had a higher sensitivity (97%) and a lower specificity (78%) for neuroendocrine differentiation compared with INSM1.

CONCLUSIONS

Although INSM1 might be a meaningful adjunct in the differential diagnosis of neuroendocrine neoplasias, a general uncritical vote for replacing the traditional markers by INSM1 may not be justified.

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.

Neuroendocrine differentiation in a large series of genetically-confirmed Ewing's sarcoma family tumor: Does it provide any diagnostic or prognostic information?

Given the potential for neuroendocrine differentiation in Ewing's sarcoma family of tumors (ESFT), we aimed to determine neuroendocrine expression in a large series of genetically-confirmed ESFT and its prognostic significance in clinically-localised neoplasms (n = 176). Slides prepared from tissue microarrays were stained for Insulinoma-associated protein 1 (INSM1), CD56, chromogranin-A and synaptophysin. INSM1 expression was present in 59% of ESFT, while synaptophysin, chromogranin-A and CD56 were expressed in only 13%, 8% and 5% of ESFT, respectively. Histological subtypes were only significantly correlated with INSM1 (p = 0.032) or CD56 (p = 0.016) immunoexpression. Regarding prognosis, no significant association was found between INSM1, synaptophysin or chromogranin-A immunoexpression and progression-free survival (PFS) or overall survival (OS). Despite the low proportion of tumors with CD56 immunoreactivity, CD56 expression was shown to correlate with both poor PFS (p < 0.001) and poor OS (p < 0.001) in the present series. In conclusion, neuroendocrine differentiation is often present in ESFT, and in the present study INSM1 expression in particular was found to be higher than previously described in Ewing's tumors. Nevertheless, this finding does not distinguish these tumors from other round cell tumors that may show focal or diffuse neuroendocrine differentiation. CD56 expression could be used as a prognostic factor in ESFT, although given the results herein obtained, we recommend a prospective validation in independent series including localized and disseminated tumors in ESFT.

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.

INSM1 expression in a subset of thoracic malignancies and small round cell tumors: rare potential pitfalls for small cell carcinoma

INSM1 is a diagnostic marker for neuroendocrine tumors originating in multiple anatomic sites. In the lung, INSM1 shows 76-97% sensitivity for neuroendocrine tumors overall. Our aim was to characterize INSM1 as a diagnostic marker for small cell carcinoma in the context of its epithelial, lymphoid, and mesenchymal morphologic mimics. Immunohistochemistry was performed on 231 tumors, including lung neuroendocrine tumors, nonneuroendocrine carcinomas of the thoracic cavity, diffuse large B-cell lymphomas, and small round cell sarcomas, using an anti-INSM1 mouse monoclonal antibody. Extent (0-100%) and intensity (1-3+) of nuclear INSM1 staining was multiplied in each case to calculate an H-score. Demographic and clinical information was obtained from the medical record. INSM1 had an overall sensitivity and specificity of 81.5% and 82.7% for small cell carcinoma, respectively, using a threshold established with a receiver operating characteristic curve. 40/48 (82.7%) small cell carcinomas were positive for INSM1, including 19/24 (79%) small cell carcinomas that were negative for chromogranin and synaptophysin. 5/5 carcinoids and 21/28 (75%) large cell neuroendocrine carcinomas showed INSM1 expression. Among nonneuroendocrine tumors, 7/38 (18%) lung adenocarcinomas, 2/17 (12%) lung squamous cell carcinomas, 4/10 (40%) thymic carcinomas, 4/12 (33%) adenoid cystic carcinomas, 1/19 (5%) diffuse large B-cell lymphomas, 4/11 (36%) alveolar rhabdomyosarcomas, and 4/23 (17%) Ewing sarcomas were positive for INSM1. No synovial sarcomas or desmoplastic small round cell tumors were positive. Weak, focal INSM1 expression alone is insufficient as a diagnostic marker for small cell carcinoma, but is sensitive and specific, easy to interpret in small biopsies, and makes a valuable addition to a diagnostic panel.

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.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

Pathologic Considerations in Gastroenteropancreatic Neuroendocrine Tumors

This review serves as a primer on contemporary neuroendocrine neoplasm classification, with an emphasis on gastroenteropancreatic well-differentiated neuroendocrine tumors. Topics discussed include general features of neuroendocrine neoplasms, general neuroendocrine marker immunohistochemistry, the distinction of well-differentiated neuroendocrine tumor from pheochromocytoma/paraganglioma and other diagnostic mimics and poorly differentiated neuroendocrine carcinoma from diagnostic mimics, the concepts of differentiation and grade and the application of Ki-67 immunohistochemistry to determine the latter, the various WHO classifications of neuroendocrine neoplasms including the 2019 WHO classification of gastroenteropancreatic tumors, organ-specific considerations for gastroenteropancreatic well-differentiated neuroendocrine tumors, immunohistochemistry to determine site of origin in metastatic well-differentiated neuroendocrine tumor of occult origin, immunohistochemistry in the distinction of well-differentiated neuroendocrine tumor G3 from large cell neuroendocrine carcinoma, and, finally, required and recommended reporting elements for biopsies and resections of gastroenteropancreatic neuroendocrine epithelial neoplasms.

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.

[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.

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.

RETRACTED: Neuroendocrine differentiation contributes to radioresistance development and metastatic potential increase in non-small cell lung cancer

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the authors and their institute. The BBA Editor-in-Chief has agreed to retract the paper. In this paper, there were two errors identified to the journal by the authors: The first error was in Western blot gel band images of Fig. 4A (p-MAPK, MAPK, p-Erk, and Stat3) and the 8 gel band images of Fig. 4G. The second error was in the cell culture images of Figures 3F, 3J, and 4E. The authors state that these errors were due to uploading mistakes in the preparation of the manuscript. The authors apologize for these errors and any inconvenience caused. The Editor-in-Chief initially agreed to retract the paper based on the identification of these two errors. Readers are able to see further discussion of the paper on the PubPeer site here: https://pubpeer.com/publications/569EB2CE7A7335D7F3F8F3FF310936

Computed Tomographic Studies of Noncalcified Nodules Related to Neuroendocrine Lung Tumor Using 68Gallium-Tagged Somatostatin Variant for Improvement in Diagnosis: A Non-Experimental, Non-Randomized, Cross-Sectional Study

Background

¹⁸Fluoro-fluorodeoxyglucose (FDG)- based positron-emission computed tomography (PET) has less specificity for noncalcified nodules (NNs). Somatostatin receptors affect the expression of normal and malignant cells. The purpose of the study was to compare the sensitivity, specificity, and accuracy of ⁶⁸Gallium-tagged DOTA-octreotate (Ga-tDO) with that of FDG PET for diagnosis of newly detected and/or untreated NNs in lung cancer patients.

Material/Methods

A total of 45 patients with lung cancer were included in the cross-sectional study and underwent Ga-tDO and FDG PET. We further confirmed observed outcomes by testing immune histochemical staining for subtype 2A of somatostatin receptor in a granuloma tissue array. The chi-square test was performed for sensitivity and specificity of predictive values among the 3 diagnostic modalities. McNemar’s test was performed to compare accuracy between Ga-tDO and FDG PET. Results were considered significant at 95% confidence level.

Results

Ga-tDO had less sensitivity (69% vs. 89%) but more specificity (91% vs. 78%) than FDG PET. Ga-tDO and FDG PET were characterized as 36 and 6 and in 36 and 3 lesions as accurate and inaccurate, respectively. There was an insignificant difference between Ga-tDO and FDG PET regarding diagnostic accuracy (p=0.7). Dosimetry results showed that the lungs were one of the least critically affected organs.

Conclusions

Ga-tDO was more specific but less sensitive than FDG PET scanning and imaging.

Correlation of neuroendocrine features with prognosis of non-small cell lung cancer

The improvement in histological diagnostic tools, including neuroendocrine markers by immunohistochemistry (IHC), has led to increased recognition of non-small cell lung cancer (NSCLC) with neuroendocrine (NE) feature. However, little is known regarding the prevalence and clinical implications of NE feature in patients with NSCLC. In this study, we performed IHC in a tissue microarray containing 451 Chinese NSCLC cases, and analyzed correlation of the expression of neuroendocrine marker with pathological and clinical features of NSCLC. The result showed that NE feature in NSCLC was detectable in almost 30% of studied patients, and tumors with NE feature were significantly correlated with pathological classification, clinical stages and cell differentiation of NSCLC. Our data also revealed that NE feature indicated worse overall survival and disease free survival. Compared with mutant p53, NE markers showed more significance as for prognostic evaluation. Multi-factor COX analysis further suggested a potential clinical impact for NE feature as an independent indicator of poor prognosis for NSCLC patients.

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.

Potential paraneoplastic syndromes and selected autoimmune conditions in patients with non-small cell lung cancer and small cell lung cancer: A population-based cohort study

BACKGROUND

Little is known about the occurrence and distribution of types of paraneoplastic syndromes (PNS) in patients with lung cancer. Identification of autoimmune PNS is particularly important for discerning them from immune-related adverse events of novel immunotherapies. We estimated the occurrence of PNS among patients with lung cancer and compared it with that in the general population.

METHODS

In this registry-based cohort study in Denmark, we identified all patients with incident primary lung cancer between 1997 and 2010, and in a general-population comparison cohort matched on calendar time, sex, age, and residence. Among patients with non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC), we estimated prevalence of potential PNS and selected autoimmune conditions and compared their incidence rates with those of equivalent conditions in the general population cohort, using hazard ratios (HRs) adjusted for baseline comorbidity.

RESULTS

There were 35,319 patients with NSCLC and 6,711 patients with SCLC. The incidence rates per 1000 person-years (95% confidence interval) of any potential PNS or selected autoimmune disorders were 135.4 (131.9-139.1) among NSCLC patients and 237.3 (224.4-250.5) among SCLC patients. Adjusted HRs for any potential PNS or selected autoimmune disorders were 4.8 (4.7-5.0) for NSCLC and 8.2 (7.6-8.8) for SCLC.

CONCLUSION

Incidence rate of any potential PNS or selected autoimmune disorders among patients with lung cancer was greater than that in the general population and was greater after SCLC than after NSCLC.

IMPACT

These results provide context to discerning PNS from adverse effects of novel immunotherapies during the clinical course of NSCLC and SCLC.

68Ga-DOTATATE PET/CT imaging of indeterminate pulmonary nodules and lung cancer

PURPOSE

18F-FDG PET/CT is widely used to evaluate indeterminate pulmonary nodules (IPNs). False positive results occur, especially from active granulomatous nodules. A PET-based imaging agent with superior specificity to 18F-FDG for IPNs, is badly needed, especially in areas of endemic granulomatous nodules. Somatostatin receptors (SSTR) are expressed in many malignant cells including small cell and non-small cell lung cancers (NSCLCs). 68Ga-DOTATATE, a positron emitter labeled somatostatin analog, combined with PET/CT imaging, may improve the diagnosis of IPNs over 18F-FDG by reducing false positives. Our study purpose was to test this hypothesis in our region with high endemic granulomatous IPNs.

METHODS

We prospectively performed 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT scans in the same 30 patients with newly diagnosed, treatment-naïve lung cancer (N = 14) or IPNs (N = 15) and one metastatic nodule. 68Ga-DOTATATE SUVmax levels at or above 1.5 were considered likely malignant. We analyzed the scan results, correlating with ultimate diagnosis via biopsy or 2-year chest CT follow-up. We also correlated 68Ga-DOTATATE uptake with immunohistochemical (IHC) staining for SSTR subtype 2A (SSTR2A) in pathological specimens.

RESULTS

We analyzed 31 lesions in 30 individuals, with 14 (45%) being non-neuroendocrine lung cancers and 1 (3%) being metastatic disease. McNemar's result comparing the two radiopharmaceuticals (p = 0.65) indicates that their accuracy of diagnosis in this indication are equivalent. 68Ga-DOTATATE was more specific (94% compared to 81%) and less sensitive 73% compared to 93%) than 18F-FDG. 68Ga-DOTATATE uptake correlated with SSTR2A expression in tumor stroma determined by immunohistochemical (IHC) staining in 5 of 9 (55%) NSCLCs.

CONCLUSION

68Ga-DOTATATE and 18F-FDG PET/CT had equivalent accuracy in the diagnosis of non-neuroendocrine lung cancer and 68Ga-DOTATATE was more specific than 18F-FDG for the diagnosis of IPNs. IHC staining for SSTR2A receptor expression correlated with tumor stroma but not tumor cells.

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.

Neuroendocrine Differentiation in Thymic Carcinomas: A Diagnostic Pitfall: An Immunohistochemical Analysis of 27 Cases

OBJECTIVES

Neuroendocrine differentiation in carcinomas of the nonneuroendocrine type has been observed in various organ systems. Awareness of this phenomenon is important since such tumors need to be separated from true neuroendocrine neoplasms because of therapeutic and prognostic consequences. To investigate this occurrence in thymic carcinomas, 27 cases of different histologies were analyzed using neuroendocrine immunohistochemical markers.

METHODS

Twenty-seven conventional thymic carcinomas from thymectomies were studied immunohistochemically with antibodies directed against synaptophysin, chromogranin A, and CD56 in addition to the standard markers for these tumors.

RESULTS

Focal expression of at least one neuroendocrine marker was identified in a total of 12 (44%) cases. Chromogranin A was positive in five (19%) cases, synaptophysin in eight (30%), and CD56 in 10 (37%). All three markers were coexpressed in four (15%) cases.

CONCLUSIONS

Neuroendocrine differentiation in conventional thymic carcinomas is a common occurrence. It is imperative to separate these tumors from true neuroendocrine neoplasms of the thymus-especially large cell neuroendocrine carcinoma-since both entities require different treatment modalities and likely show different biologic behavior. Contrary to prior suggestions, neuroendocrine differentiation should not be used to distinguish thymic carcinomas from thymomas, and these tumors should not be regarded as "mixed carcinomas."

The comparative pathology of genetically engineered mouse models for neuroendocrine carcinomas of the lung

INTRODUCTION

Because small-cell lung carcinomas (SCLC) are seldom resected, human materials for study are limited. Thus, genetically engineered mouse models (GEMMs) for SCLC and other high-grade lung neuroendocrine (NE) carcinomas are crucial for translational research.

METHODS

The pathologies of five GEMMs were studied in detail and consensus diagnoses reached by four lung cancer pathology experts. Hematoxylin and Eosin and immunostained slides of over 100 mice were obtained from the originating and other laboratories and digitalized. The GEMMs included the original Rb/p53 double knockout (Berns Laboratory) and triple knockouts from the Sage, MacPherson, and Jacks laboratories (double knockout model plus loss of p130 [Sage laboratory] or loss of Pten [MacPherson and Jacks laboratories]). In addition, a GEMM with constitutive co-expression of SV40 large T antigen and Ascl1 under the Scgb1a1 promoter from the Linnoila laboratory were included.

RESULTS

The lung tumors in all of the models had common as well as distinct pathological features. All three conditional knockout models resulted in multiple pulmonary tumors arising mainly from the central compartment (large bronchi) with foci of in situ carcinoma and NE cell hyperplasia. They consisted of inter- and intra-tumor mixtures of SCLC and large-cell NE cell carcinoma in varying proportions. Occasional adeno- or large-cell carcinomas were also seen. Extensive vascular and lymphatic invasion and metastases to the mediastinum and liver were noted, mainly of SCLC histology. In the Rb/p53/Pten triple knockout model from the MacPherson and Jacks laboratories and in the constitutive SV40/T antigen model many peripherally arising non-small-cell lung carcinoma tumors having varying degrees of NE marker expression were present (non-small-cell lung carcinoma-NE tumors). The resultant histological phenotypes were influenced by the introduction of specific genetic alterations, by inactivation of one or both alleles of specific genes, by time from Cre activation and by targeting of lung cells or NE cell subpopulations.

CONCLUSION

The five GEMM models studied are representative for the entire spectrum of human high-grade NE carcinomas and are also useful for the study of multistage pathogenesis and the metastatic properties of these tumors. They represent one of the most advanced forms of currently available GEMM models for the study of human cancer.

High-grade fetal adenocarcinoma of the lung is a tumour with a fetal phenotype that shows diverse differentiation, including high-grade neuroendocrine carcinoma: a clinicopathological, immunohistochemical and mutational study of 20 cases

AIMS

High-grade fetal adenocarcinoma (H-FLAC) is a rare variant of pulmonary adenocarcinoma; this study aims to elucidate its clinicopathological features and genetic abnormalities.

METHODS AND RESULTS

Clinicopathological, immunohistochemical and mutational analyses were performed on 20 surgically resected lung cancers that showed H-FLAC histology in various proportions. These tumours predominantly occurred in elderly males and in 10 patients who were heavy smokers. Four cases were pure H-FLAC, and 16 cases were mixed H-FLAC, which were found to be combined with conventional-type adenocarcinoma (15 cases), large-cell neuroendocrine carcinoma (three cases), small-cell carcinoma (one case), enteric adenocarcinoma (two cases), choriocarcinoma (two cases), and a solid-clear cell pattern (seven cases). The fetal phenotype and diverse differentiation were supported by the immunoexpression of α-fetoprotein (95%), thyroid transcription factor-1 (TTF-1) (50%), neuroendocrine markers (30-45%), proneural markers (50-69%), and CDX2 (40%). Except for TTF-1 expression (pure H-FLACs, 0%; mixed H-FLACs, 63%), there were no significant differences in histological or immunohistochemical findings between pure and mixed H-FLACs. EGFR, KRAS, BRAF and PIK3CA mutations were identified in 20%, 0%, 0% and 7% of the tumours, respectively.

CONCLUSIONS

Lung adenocarcinomas with H-FLAC features possess the potential for multidirectional differentiation, and are not strongly associated with known major driver gene mutations.

Plasma neuron-specific enolase level as a prognostic marker in patients with non-small cell lung cancer receiving gefitinib

Determination of the presence of epidermal growth factor receptor (EGFR) gene mutation is useful for predicting the efficacy of gefitinib. However, the survival rate following the initiation of treatment with gefitinib varies among individuals. A retrospective study was conducted to investigate the associations of the pretreatment serum pro-gastrin-releasing peptide (pro-GRP) and plasma neuron-specific enolase (NSE) levels to the patient survival rate following initiation of treatment with gefitinib in non-small cell lung cancer (NSCLC) patients receiving gefitinib treatment. Patients with NSCLC harboring EGFR gene mutations who received gefitinib therapy between 2004 and 2012 were included in the study. Data from a total of 41 patients were analyzed. The serum pro-GRP level was measured in 31 patients and the plasma NSE in 22 patients. The progression-free survival (PFS) (P=0.013) and overall survival (OS) (P=0.014, log-rank test) rates decreased as the plasma NSE level increased. Statistical analysis using a Cox proportional hazards regression model adjusted for age, gender, performance status (PS) and disease stage showed that higher NSE levels were associated with shorter PFS (P=0.021) and OS (P=0.0024). By contrast, no association was detected between the serum level of pro-GRP and survival rate. The results suggest that pretreatment NSE measurement could be clinically useful in patients with NSCLC scheduled to receive gefitinib treatment.

Paraneoplastic limbic encephalitis in a male with squamous cell carcinoma of the lung

Background

Paraneoplastic limbic encephalitis (PLE) is a rare syndrome characterized by memory impairment, symptoms of hypothalamic dysfunction, and seizures. It commonly precedes the diagnosis of cancer. Small-cell lung cancer is the neoplasm that is most frequently reported as the etiology underlying PLE.

Case Report

This report describes a male patient who presented with neurologic symptoms consistent with anterograde amnesia, apathy, and disorientation. MRI revealed diffuse hyperintensities located predominantly in the medial bitemporal lobes, basal ganglia, frontal lobes, and leptomeninges on fluid attenuated inversion recovery images, suggesting PLE. Study of the primary tumor revealed squamous cell carcinoma of the lung. The patient was treated with neoadjuvant chemotherapy followed by surgery and adjuvant chemoradiotherapy, which resulted in his neurologic symptoms gradually improving.

Conclusions

PLE might be a rare debut of squamous cell carcinoma of the lung. Treatment of the primary tumor may improve the neurologic symptoms.

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).

Erk/MAP kinase signaling pathway and neuroendocrine differentiation of non-small-cell lung cancer

INTRODUCTION

Almost all small-cell lung cancers (SCLC) and carcinoid tumors express neuroendocrine differentiation (NED), and 10% to 20% of non-small-cell lung cancers (NSCLC) are associated with NED. Although distinct clinical features and histology of SCLC and carcinoid tumors are well recognized, the clinical significance and the molecular basis of NED in NSCLC remain unclear.

METHODS

To explore the potential molecular pathway involved in NED of NSCLC and its clinical relevance, we conducted investigations using an NSCLC cell line (NCI-H157) as a NED induction model, and explored the potential intracellular signal transduction pathways involved in NED of NSCLC. We confirmed our findings using activators versus inhibitors to these signal transduction pathways in vitro. We also performed immunohistochemical stains of phospho-Erk1/2 of lung cancer specimens known to have NED and explored its clinical relevance.

RESULTS

We discovered that NED of NSCLC was associated with the activation of Erk1/2-mitogen-activated protein kinases (MAPK) signal transduction pathway, and the inhibition of the Akt signal transduction pathway. Using specific activator (Pb) and inhibitors (siRNA-Erk1/2 and U0126) to the Erk1/2-MAP-kinase pathway, as well as the inhibitor (LY294002) to the Akt pathway, we found that Erk1/2-MAP-kinase activation was essential for NED of NCI-H157 cells. Staining of Erk1/2-MAP-kinase pathway revealed a high rate of positivity in NSCLC tumors with NED when compared with other neuroendocrine lung tumors.

CONCLUSIONS

To our knowledge, our findings are the first to describe the potential involvement of Erk/MAPK signal transduction pathway of NSCLC in the association with NED. Further investigation of the Erk/MAPK signal transduction pathway of NSCLC may yield discoveries in identifying specific molecular targets for the treatment of NSCLC with NED.

Combined large cell neuroendocrine carcinoma with giant cell carcinoma of the lungs: a case report

Combined large cell neuroendocrine carcinoma of the lungs (combined LCNEC) with giant cell carcinoma is extremely rare. A 65-year-old man was found to have an abnormal shadow in his left lung field. Computed tomography revealed a solid, round mass measuring 2.8 × 2.2 cm that was located in the left S9. The patient underwent left lower lobectomy and mediastinal lymph node dissection. Histopathological examination revealed an LCNEC, combined with giant cell carcinoma. The patient received by S-1 (TS-1, an oral fluoropyrimidine) chemotherapy, and he has been disease-free for over 8 months. Combined LCNEC with giant cell carcinoma is an extremely rare tumor with high malignant potential, and thus, multidisciplinary therapy and close follow-up are advised.

High-grade lung adenocarcinoma with fetal lung-like morphology: clinicopathologic, immunohistochemical, and molecular analyses of 17 cases

Low-grade lung adenocarcinoma of fetal lung type, which is well characterized by its unique clinicopathologic and molecular features, is recognized as a distinct variant of lung cancer. In contrast, high-grade lung adenocarcinoma with fetal lung-like morphology (HG-LAFM) has not been studied widely. To characterize this subset better, we analyzed 17 high-grade adenocarcinomas with at least focal component resembling a developing epithelium in the pseudoglandular phase of the fetal lung. These rare (ca. 0.4%) carcinomas occurred predominantly in elderly men with a heavy smoking history, who showed elevated serum α-fetoprotein in 4 of 5 cases tested. Histologic examination revealed a fetal lung-like component as a focal finding accounting for 5% to 60% of the total tumor volume. It was invariably admixed with tissues having a morphology not resembling that of a fetal lung. A coexisting non-fetal lung-like element was quite heterogenous in appearance, showing various growth patterns. However, clear-cell (88%), hepatoid (29%), and large cell neuroendocrine carcinoma (24%) histology seemed overrepresented. HG-LAFM was characterized immunohistochemically by frequent expression of α-fetoprotein (41%), glypican-3 (88%), SALL-4 (59%), neuroendocrine markers (82%), CDX-2 (35%), and p53 (65%). HG-LAFM was molecularly heterogenous in that EGFR or KRAS mutation was observed in 22% of cases tested for both. Our data indicate that HG-LAFMs might form a coherent subgroup of lung adenocarcinomas. However, the uniformly focal nature of the fetal lung-like element, widely diverse coexisting non-fetal lung-like histology, and inhomogenous molecular profiles lead us to believe that HG-LAFM is best regarded as a morphologic pattern showing characteristic association with several clinicopathologic parameters rather than a specific tumor entity.

Neuroendocrine tumours--challenges in the diagnosis and classification of pulmonary neuroendocrine tumours

Pulmonary neuroendocrine (NE) proliferations are a diverse group of disorders which share distinct cytological, architectural and biosynthetic features. Tumours composed of NE cells are dispersed among different tumour categories in the WHO classification of tumours and as such do not conform to a singular group with regards to treatment and prognosis. This is reflected by the highly variable behaviour of NE proliferations, ranging from asymptomatic, for instance in diffuse idiopathic pulmonary NE cell hyperplasia and tumourlets, to highly malignant cancers such as small cell lung cancer and large cell NE carcinoma. In this review NE proliferations are described as distinct entities ranging from low grade lesions to high grade cancers. The differential diagnoses are considered with each of the entries. Finally, mention is made of tumours which may show some NE features.

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.

Neuroendocrine differentiation in head and neck squamous cell carcinoma

OBJECTIVE

Tumours with neuroendocrine differentiation frequently express chromogranin A, synaptophysin and somatostatin receptors. The role of neuroendocrine differentiation in head and neck squamous cell carcinoma is not yet clear.

METHOD

The presence of chromogranin A, synaptophysin and somatostatin receptors was studied immunohistochemically in 78 head and neck squamous cell carcinoma specimens.

RESULTS

Sparse chromogranin A expression was found in 41 per cent, associated with high chromogranin A messenger RNA expression and the presence of dense core granules. Low synaptophysin expression was found in 18 per cent. The highest staining scores were found for somatostatin receptor 5 (82 per cent), followed by somatostatin receptor 1 (69 per cent) and somatostatin receptor 2 (54 per cent), whereas somatostatin receptors 3 and 4 expression was low. Expression was not correlated with tumour stage or survival.

CONCLUSION

Cells with neuroendocrine differentiation are sparsely scattered in some head and neck squamous cell carcinomas. Their pathophysiological role is elusive. In contrast, somatostatin receptor and particularly somatostatin receptor 5 expression is frequent in head and neck squamous cell carcinoma. Somatostatin receptor expression is not considered to indicate neuroendocrine differentiation in head and neck squamous cell carcinoma.

Extrapulmonary small cell carcinoma: a clinicopathological study with identification of potential diagnostic mimics

AIMS

To evaluate the clinicopathological features of small cell carcinoma arising outside the lung.

METHODS AND RESULTS

Thirty-seven cases with a pathology diagnosis of extrapulmonary small cell carcinoma (EPSCC) were selected. The clinical notes were reviewed and tumour blocks were selected for a fresh haematoxylin and eosin (H&E) section and immunohistochemical stains. The most common tumour locations were cervix and bladder. Twenty-five cases (68%) were finally diagnosed as EPSCC, nine of which were found with coexisting non small cell carcinoma. Two cases (5%) were diagnosed as large cell neuroendocrine carcinoma (LCNEC) of the cervix. The remainder was classified as 10 poorly differentiated carcinomas (PDCs) (27%). Positive staining for thyroid transcription factor 1 (TTF-1) was noted in nine cases of EPSCC and in none of the cases of PDC (P = 0.034). Synaptophysin immunoreactivity was found in 20 cases of EPSCC and two cases of PDC with neuroendocrine differentiation (P = 0.002), as well as two cases of LCNEC. 34βE12 was positive in eight cases of SCC and two cases of PDC.

CONCLUSIONS

Based on this series, EPSCC may be overdiagnosed. Immunohistochemistry for TTF-1, used in combination with synaptophysin, may help to discriminate EPSCC from PDC.

Prognostic value of synaptophysin and chromogranin a expression in patients receiving palliative chemotherapy for advanced non-small-cell lung cancer

BACKGROUND

Chemotherapy is the principal treatment method for patients with advanced non-small-cell lung cancer (NSCLC). Treatment with platinum-based and novel chemotherapeutic regimens, compared to monotherapy, slightly increases the response rates to 20-40%. The predictive and prognostic values of molecular factors are highly variable; however, data on clinical-demographic factors are still burdened by significant limitations.

OBJECTIVES

The aim of this study was to assess the prognostic value of synaptophysin and chromogranin A protein expression in patients receiving palliative chemotherapy for advanced NSCLC.

METHODS

The study population consisted of 23 women and 116 men. The median age was 57.3 years. Expression of synaptophysin and chromogranin was assessed using a two-step model of immunohistochemical staining. Level 0 represented lack of activity, while level 1 represented its expression.

RESULTS

Expression of synaptophysin and chromogranin A was observed in 12 (8.6%) and 5 (3.6%) patients, respectively. The risk of death was significantly lower in patients with expression of synaptophysin (p = 0.008) and chromogranin A (p = 0.014). The 12- and 24-month survival rate of patients with synaptophysin expression was 64% (95% CI 0.35-0.93), while for patients without expression it was 46% (95% CI 0.36-0.56) and 16% (95% CI 0.07-0.25), respectively. The 12- and 24-month survival rate of patients with chromogranin expression was 80% (95% CI 0.44-1.00), while for chromogranin A-negative patients it was 47% (95% CI 0.37-0.57) and 19% (95% CI 0.10-0.28), respectively. We did not observe associations between expression of synaptophysin and chromogranin A and the other typical prognostic factors.

CONCLUSIONS

Expression of synaptophysin and chromogranin A was associated with a longer median overall survival and might have prognostic value. These results should be confirmed in a prospective study.

[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.

Neuroendocrine differentiation as an indicator of chemosensitivity and prognosis in nonsmall cell lung cancer

CONTEXT

Nonsmall cell lung cancers with neuroendocrine differentiation (NSCLC-ND) may demonstrate biologic behavior intermediate between NSCLC and small cell lung cancer (SCLC) with impact on prognosis.

METHODS

We analyzed 116 consecutive patients with Stage III and IV NSCLC who were diagnosed and treated between 2001 and 2006. Using immuno-histochemical staining for neuron-specific enolase (NSE), chromogranin A (ChrA), and synaptophysin (Syn), 29 (25%) NSCLC-ND were identified.

RESULTS

Expression of NSE was present in 22.4%, ChrA in 15.5% and Syn in 14.8% of patients with NSCLC. Therapeutic response was significantly better in the NSCLC-ND group and specimens with > 30% neuroendocrine (NE)-differentiated tumor cells showed favourable therapeutic response (P < 0.05). Multivariate binary logistic regression showed that percentage of NE positive tumor cells was a significant independent prognostic factor associated with a favourable outcome. Receiver operating characteristic (ROC) curves and areas under ROC curves confirmed that percentage of NE-differentiated tumor cells could be useful prediction factor of therapeutic response. Moreover, according to percentage of NE-differentiated tumor cells, optimal cutoffs and related sensitivities and specificities were determined for each markers.

CONCLUSION

Advanced-stage NSCLC with NE tumor cells are clinically less aggressive tumors. Percentage of NE-differentiated tumor cells identifies patients with favourable therapy response to paclitaxel-cisplatin.