Lung surfactant protein-A and carcinoembryonic antigen in pleural effusions due to lung adenocarcinoma and malignant mesothelioma

Our plain-English summary of Lung surfactant protein-A and carcinoembryonic antigen in pleural effusions due to lung adenocarcinoma and malignant mesothelioma, by N. Shijubo, Y. Honda, T. Fujishima, et al (The European Respiratory Journal, 1995).

The study

• Authors: N. Shijubo, Y. Honda, T. Fujishima, H. Takahashi, T. Kodama, Y. Kuroki, T. Akino, S. Abe
• Journal: The European Respiratory Journal
• Published: 1995;8(3):403-6
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Lung surfactant protein-A (SP-A) is a major phospholipid-associated glycoprotein in surfactant, and is a useful immunohistochemical marker for lung adenocarcinoma. Carcinoembryonic antigen (CEA) has not been immunohistochemically detected in mesothelioma. In pleural effusions due to malignant mesothelioma, very low concentrations of SP-A and CEA can be expected. We studied the value of combined determinations of CEA and SP-A in pleural fluid to distinguish between lung adenocarcinoma and mesothelioma. SP-A and CEA concentrations were measured in pleural effusions from 78 patients with lung adenocarcinoma and 10 with malignant mesothelioma. SP-A concentrations in pleural effusions due to lung adenocarcinoma and mesothelioma were 516 +/- 140 and 16.9 +/- 3.6 ng.ml-1 (mean +/- SEM), respectively. CEA concentrations in pleural effusions due to lung adenocarcinoma and mesothelioma were 239 +/- 92.4 and 1.7 +/- 0.3 ng.ml-1, respectively. SP-A values did not exceed 100 ng.ml-1 in any of 10 mesotheliomas, whilst in 37 of 78 lung adenocarcinomas they did. CEA values did not exceed 10 ng.ml-1 in any of 10 mesotheliomas, whilst in 53 of 78 lung adenocarcinomas they did. Increased values of SP-A and/or CEA were found in pleural effusions from 67 of 78 lung adenocarcinomas. It is concluded that a combination of CEA and SP-A assays in pleural effusions will be helpful for discriminating lung adenocarcinoma from mesothelioma.

In plain English

This study, from Sapporo Medical University and the National Cancer Center Hospital East in Japan, measured two proteins, lung surfactant protein-A (SP-A) and carcinoembryonic antigen (CEA), in fluid that collects around the lungs (pleural effusions). The aim was to see whether these proteins could help tell lung adenocarcinoma apart from malignant mesothelioma. It included 78 patients with lung adenocarcinoma and 10 patients with malignant mesothelioma who had a history of asbestos exposure. The article does not name fiber types. Average SP-A was 516 ng/ml in the adenocarcinoma group and 16.9 ng/ml in the mesothelioma group. Average CEA was 239 and 1.7 ng/ml respectively. Both differences were statistically significant. No mesothelioma sample exceeded the cut-offs used (100 ng/ml for SP-A, 10 ng/ml for CEA). Among adenocarcinoma samples, 53 of 78 exceeded the CEA cut-off, 37 of 78 exceeded the SP-A cut-off, and 67 of 78 exceeded one or both. The authors concluded that combining the two tests on pleural fluid will be helpful for distinguishing lung adenocarcinoma from mesothelioma when there is no apparent lung tumour. They noted that CEA alone stayed below the cut-off in a number of adenocarcinoma effusions.

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: Laboratory diagnostic study comparing levels of two markers (SP-A and CEA) in pleural fluid from patients with two different cancers
• Who was studied: 78 patients with lung adenocarcinoma whose pleural effusions contained malignant cells, and 10 patients with malignant mesothelioma (7 epithelial, 3 biphasic) who had a history of asbestos exposure. The patients were at Sapporo Medical University School of Medicine and the National Cancer Center Hospital East, Japan. Dates of patient collection are not given.
• Exposure: The mesothelioma patients had a history of asbestos exposure. No fiber type, job or dose is given. The study's measurements were SP-A (by ELISA) and CEA (by radioimmunoassay) in pleural fluid.
• Main results:
  • SP-A in pleural effusions, mean plus or minus SEM: lung adenocarcinoma 516 plus or minus 140 ng/ml (range 3.0 to 9,530; median 87.6); mesothelioma 16.9 plus or minus 3.5 ng/ml (range 2.0 to 38.2; median 17.0). Adenocarcinoma values were significantly higher (p less than 0.001).
  • CEA in pleural effusions: lung adenocarcinoma 239 plus or minus 92.4 ng/ml (range 1.0 to 6,530; median 26.3); mesothelioma 1.7 plus or minus 0.3 ng/ml (range 0.9 to 3.4; median 1.7). Adenocarcinoma values were significantly higher (p less than 0.001).
  • SP-A and CEA levels were not significantly correlated across all patients (r=0.129).
  • CEA above 10 ng/ml: 53/78 (64%) of lung adenocarcinoma effusions versus 0/10 mesothelioma effusions.
  • SP-A above 100 ng/ml: 37/78 (47%) of lung adenocarcinoma effusions versus 0/10 mesothelioma effusions.
  • CEA above 10 and/or SP-A above 100 ng/ml: 67/78 (86%) of lung adenocarcinoma effusions versus 0/10 mesothelioma effusions. The discrimination rate rose from 64% with CEA alone to 86% with both assays.
  • Immunohistochemistry showed no SP-A expression in the 10 mesothelioma tissues (data not shown).
• The authors' conclusion: The authors concluded that, in a malignant pleural effusion without an apparent lung tumour, combined pleural fluid SP-A and CEA testing will be helpful for discriminating lung adenocarcinoma from mesothelioma.
• Limitations the authors state:
  • CEA values in a number of lung adenocarcinoma effusions did not exceed the cut-off value.
  • It remains unclear whether SP-A production by malignant cells is specific to lung adenocarcinoma.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Carcinoembryonic Antigen (CEA), Pleural Effusion, Lung Adenocarcinoma, Malignant Mesothelioma, Glycoprotein, Mesothelioma.

Related studies

• Clara cell protein (CC-16) and surfactant-associated protein A (SP-A) in asbestos-exposed workers — O. Lesur, A.M. Bernard, et al. (1996)
• Ber-EP4 for differentiating adenocarcinoma from reactive and neoplastic mesothelial cells in serous effusions. Comparison with carcinoembryonic antigen, B72.3 and Leu-M1 — M.E. Bailey, R.W. Brown, et al. (1996)
• The distinction of adenocarcinoma from malignant mesothelioma in cell blocks of effusions: the role of routine mucin histochemistry and immunohistochemical assessment of carcinoembryonic antigen, keratin proteins, epithelial membrane antigen, and milk fat globule-derived antigen — E.S. Cibas, J.M. Corson, et al. (1987)
• Immunocytological staining reactions of anti-carcinoembryonic antigen, Ca, and anti-human milk fat globule monoclonal antibodies on benign and malignant exfoliated mesothelial cells — A.K. Ghosh, E.B. Butler (1987)
• Evaluation of pleural CYFRA 21-1 and carcinoembryonic antigen in the diagnosis of malignant pleural effusions — G. Salama, M. Miédougé, et al. (1998)
• Keratin proteins and carcinoembryonic antigen in lung carcinoma: an immunoperoxidase study of fifty-four cases, with ultrastructural correlations — J.W. Said, G. Nash, et al. (1983)

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