Cytokeratin 19 expression in primary thoracic tumors and lymph node metastases

Our plain-English summary of Cytokeratin 19 expression in primary thoracic tumors and lymph node metastases, by K. Masai, K. Nakagawa, A. Yoshida, et al (Lung Cancer, 2014).

The study

• Authors: K. Masai, K. Nakagawa, A. Yoshida, H. Sakurai, S. Watanabe, H. Asamura, K. Tsuta
• Journal: Lung Cancer
• Published: 2014;86(3):318-23
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The use of one-step nucleic acid amplification (OSNA), which allows for the rapid intraoperative detection of lymph node (LN) metastasis, is becoming more widely accepted in breast cancer. To provide basic data for the development of this method for lung tumors, we conducted a large-scale investigation of cytokeratin (CK) 19 expression in thoracic tumors.

Patients And Methods: We examined CK19 expression in specimens from a total of 801 surgically resected samples of primary lung adenocarcinoma (ADC), squamous cell carcinoma (SQC), large-cell carcinoma (LCC), pleomorphic carcinoma (PC), large cell neuroendocrine carcinoma (LCNEC), small cell carcinoma (SCC), and carcinoid tumor (CT) as well as pleural malignant mesothelioma and lung metastatic deposits from breast cancer using tissue microarrays (TMAs) and whole sections. We also compared the CK19 expression status between primary sites and LN metastatic deposits.

Results: The overall rate of CK19 expression as observed on TMAs and whole sections in the 801 analyzed cases was 88.0%. CK19 expression was detected in 94.6% of ADCs, 93.6% of SQCs, 54.5% of LCCs, 54.8% of PCs, 77.4% of LCNECs, 31.8% of SCCs, 34.0% of CTs, and 92.9% of malignant mesotheliomas. Expression of CK19 was also detected in 90.9% of lung metastatic deposits from breast carcinomas. CK19 expression was maintained between CK19-positive primary sites and the corresponding LN metastatic deposits. Of note, a portion of CK19-negative primary tumors showed upregulation of CK19 protein expression in LN metastases.

Conclusions: Most thoracic tumors, except for PCs, CTs, and SCCs, were positive for CK19. We also found that CK19 expression was maintained between CK19-positive primary tumors and the corresponding LN metastatic deposits. These results may be useful in the development of the OSNA method for the intraoperative detection of LN metastasis in non-small cell lung cancer (NSCLC).

Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

In plain English

This was a retrospective laboratory study of stored tumor tissue from the National Cancer Center Hospital in Tokyo. It did not study asbestos exposure. The authors stained samples from 801 cases seen between 1997 and 2007 for a protein called cytokeratin 19 (CK19). The cases were 726 primary lung tumors of seven types, 42 malignant mesotheliomas, and 33 breast cancers that had spread to the lung. The aim was basic data for OSNA, a rapid test that looks for cancer spread to lymph nodes during surgery. On small tissue cores, CK19 was found in 39 (92.9%) of 42 malignant mesotheliomas. After larger sections of the negative cases were also checked, the final rate was 95.2% for mesotheliomas, 99.3% for adenocarcinomas and 42.0% for carcinoid tumors. Among 38 lung tumors that had spread to lymph nodes, all 22 CK19-positive tumors were also positive in the nodes. In addition, 7 of 16 CK19-negative tumors were positive in the nodes. The authors concluded that most thoracic tumors, except pleomorphic carcinomas, carcinoid tumors and small cell carcinomas, were CK19-positive. They noted that their protein data do not apply directly to the mRNA-based test.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective immunohistochemical (tissue staining) study using tissue microarrays and whole tissue sections
• Who was studied: 801 surgically treated cases seen at the National Cancer Center Hospital, Tokyo, Japan, between 1997 and 2007. They were 726 primary lung tumors (294 adenocarcinomas, 157 squamous cell carcinomas, 11 large cell carcinomas, 42 pleomorphic carcinomas, 106 large-cell neuroendocrine carcinomas, 66 small cell carcinomas, 50 carcinoid tumors), plus 42 malignant mesotheliomas and 33 metastatic lung deposits from breast carcinomas.
• Exposure: No asbestos or other exposure was studied. The study measured expression of the protein cytokeratin 19 (CK19) in tumor tissue by immunohistochemical staining.
• Main results:
  • On tissue microarray sections, CK19 was detected in 643 (80.3%) of all 801 cases. This included 39 (92.9%) of 42 malignant mesotheliomas, 278 (94.6%) of 294 adenocarcinomas, 21 (31.8%) of 66 small cell carcinomas and 17 (34.0%) of 50 carcinoid tumors.
  • After whole-section analysis of the negative cases, CK19 expression rose from 80.3% to 88.0% of all cases. Final rates were 99.3% for adenocarcinoma, 96.2% for squamous cell carcinoma, 81.8% for large cell carcinoma, 71.4% for pleomorphic carcinoma, 87.7% for large-cell neuroendocrine carcinoma, 59.1% for small cell carcinoma, 42.0% for carcinoid tumor and 95.2% for malignant mesotheliomas.
  • CK19 was detected in 30 (90.9%) of 33 lung metastatic deposits from breast carcinomas. This rate was unchanged after whole-section analysis.
  • Among adenocarcinoma subtypes, there were no statistical differences in CK19 expression (P = 0.31).
  • In lymph node metastases from 38 lung tumors, all node deposits from the 22 CK19-positive primary tumors were CK19-positive. In addition, 7 (43.8%) of 16 node deposits from CK19-negative primary tumors were CK19-positive.
• The authors' conclusion: The authors concluded that most thoracic tumors except pleomorphic carcinomas, carcinoid tumors and small cell carcinomas were CK19-positive. They found that CK19 expression was maintained between CK19-positive primary tumors and their lymph node metastases. They stated these results may be useful in developing the OSNA method for detecting lymph node metastasis during surgery in non-small cell lung cancer.
• Limitations the authors state:
  • The OSNA assay measures CK19 mRNA, so the authors' protein expression data are not directly applicable to the assay.
  • Some inflammatory cells, including plasma cells and epithelioid macrophages, showed weak CK19 staining. The authors said results must be interpreted carefully.
  • Differences in antibody source, dilution and antigen retrieval method can significantly affect immunohistochemistry results.

Topics

Medical terms in this study, explained in our Lexicon: Metastasis, Lung Adenocarcinoma, Squamous Cell Carcinoma, Carcinoma, Pleomorphic, Malignant Mesothelioma, Non-Small Cell Lung Cancer.

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