[Molecular pathology of lung cancer. State of the art 2014]

Liquid Biopsy Promotes Non-Small Cell Lung Cancer Precision Therapy

The range of potential applications of liquid biopsies for non-small cell lung cancer management is expanded by the use of circulating tumor deoxyribonucleic acid and circulating tumor cells. Principal studies have demonstrated the predictive accuracy of droplet digital polymerase chain reaction detection, next-generation sequencing, and circulating tumor cells detection in patients with non-small cell lung cancer. The translational potential of these liquid biopsy technologies promotes the improvement of sensitivity and specificity in genomic and molecular methods. Here, we highlight the realities and challenges associated with the use of liquid biopsies for the detection of non-small cell lung cancer in patients. However, liquid biopsy technologies including circulating tumor cells detection, droplet digital polymerase chain reaction detection, and next-generation sequencing detection for precision therapy in non-small cell lung cancer will show substantive clinical applications in the future.

[Diagnosis, prognosis, and prediction of non-small cell lung cancer. Importance of morphology, immunohistochemistry and molecular pathology]

Tumor diagnostics are based on histomorphology, immunohistochemistry and molecular pathological analysis of mutations, translocations and amplifications which are of diagnostic, prognostic and/or predictive value. In recent decades only histomorphology was used to classify lung cancer as either small (SCLC) or non-small cell lung cancer (NSCLC), although NSCLC was further subdivided in different entities; however, as no specific therapy options were available classification of specific subtypes was not clinically meaningful. This fundamentally changed with the discovery of specific molecular alterations in adenocarcinoma (ADC), e.g. mutations in KRAS, EGFR and BRAF or translocations of the ALK and ROS1 gene loci, which now form the basis of targeted therapies and have led to a significantly improved patient outcome. The diagnostic, prognostic and predictive value of imaging, morphological, immunohistochemical and molecular characteristics as well as their interaction were systematically assessed in a large cohort with available clinical data including patient survival. Specific and sensitive diagnostic markers and marker panels were defined and diagnostic test algorithms for predictive biomarker assessment were optimized. It was demonstrated that the semi-quantitative assessment of ADC growth patterns is a stage-independent predictor of survival and is reproducibly applicable in the routine setting. Specific histomorphological characteristics correlated with computed tomography (CT) imaging features and thus allowed an improved interdisciplinary classification, especially in the preoperative or palliative setting. Moreover, specific molecular characteristics, for example BRAF mutations and the proliferation index (Ki-67) were identified as clinically relevant prognosticators. Comprehensive clinical, morphological, immunohistochemical and molecular assessment of NSCLCs allow an optimized patient stratification. Respective algorithms now form the backbone of the 2015 lung cancer World Health Organization (WHO) classification.

Transcriptome analysis of distinct long non-coding RNA transcriptional fingerprints in lung adenocarcinoma and squamous cell carcinoma

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related death, including two major pathologic subtypes, adenocarcinoma (AD) and squamous cell carcinoma (SCC). There are significant differences in the aberrant gene profiling and molecular characteristics among LUAD and LUSC, which lead to the different chemotherapeutic regimens administered to the two NSCLC subtypes. Therefore, unique genetic or epigenetic accurately distinguishing these two subtypes is critical for the diagnosis and treatment of patients. In this study, we tried to develop and validate novel long non-coding RNA (lncRNA)-based signatures to facilitate the diagnosis and individualized treatment of LUAD and LUSC. To analyze the distinct lncRNA profiling in LUAD and LUSC, the paired tissue samples of RNA sequencing or microarray data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) was used. We found that lncRNA expression pattern is different in LUAD and LUSC, and three up-regulated and down-regulated lncRNAs expressions in LUAD and LUSC tissues were validated. In addition, knockdown of the up-regulated lncRNA AFAP1-AS1 and LINC00511 impaired LUAD cell proliferation, while knockdown of PVT1 inhibited LUSC cell growth. Furthermore, four 6-lncRNAs signature expression patterns were found to be significantly associated with LUAD and LUSC patient overall and progression-free survival. Taken together, the different lncRNAs signature might accurately distinguish LUAD and LUSC and predict clinical outcome for these two different subtypes of NSCLC.

[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.

Individualized medicine and demographic change as determining workload factors in pathology: quo vadis?

The advent of individualized medicine with novel guidelines, extended quality assessment as well as intensified conventional, immunohistochemical, and molecular characterization of diseases has led to a substantial increase of pathologists' workload. Furthermore, in industrialized countries, we are facing the challenges of demographic change with an aging population. This raises the question of how pathology will be affected by these developments in the future. We extracted German population data and data on the number of board-certified physicians and pathologists from official sources. These data were reviewed in the light of data on caseload, case complexity, auxiliary diagnostic procedures, and matching patient data from a large German pathology department serving as a sector independent regional service provider. The refinement of diagnostic procedures over the last decade has resulted in a 60 % increase in slide numbers per case, doubling of immunohistochemistry procedures, and more than tripling of molecular analyses. Correlation of this development to demographics suggests that an aging population will further increase the caseload and case complexity in the coming decades since patient age is tightly linked to both parameters. This development is currently not accompanied by a sufficient increase in the number of pathologists. Our data point toward an imbalance between the increase in pathology workload and the number of pathologists. Extrapolations suggest a further aggravation of this development in the future. Thus, healthcare systems need to address this problem urgently in order to cope with these challenges.

[Molecular diagnostics of non-small cell lung cancer: New markers and technologies]

Lung cancer is the prototypical tumor entity for the development of new diagnostic and individualized therapeutic strategies based on molecular patient stratification. Developments in this field specifically concentrate on predictive biomarkers for the response to conventional therapeutic agents, novel drugs targeting specific mutations and also new immunomodulatory drugs. The multitude of upcoming new predictive biomarkers requires the development and implementation of efficient test strategies and comprehensive technical methods, specifically when tissue restrictions inherent to lung cancer diagnostics are also taken into account. Novel procedures and technical aspects of these issues are discussed in this review.