Distinct Spectral Profiles of Pleural Effusions from Malignant Tumors Using Raman Spectroscopy

Our plain-English summary of Distinct Spectral Profiles of Pleural Effusions from Malignant Tumors Using Raman Spectroscopy, by M. Kujdowicz, P. Jeleń, M. Sitarz, et al (International Journal of Molecular Sciences, 2025).

The study

• Authors: M. Kujdowicz, P. Jeleń, M. Sitarz, M. Marcinek, J. Włodarczyk, M. Wiłkojć, L. Rudnicka, D. Adamek
• Journal: International Journal of Molecular Sciences
• Published: 2025;26(23)
• Read it: PubMed · Publisher · Free full text

Abstract

Raman spectroscopy is a powerful method in the field of cancer diagnosis, for which various sample types and measurement modalities can be used. In this study, pleural effusion samples from twenty patients with suspected malignancies were analyzed. After fluid samples were fixed with ethanol and dried, high-quality spectra were taken at three different points using two laser lines. Principal Component Analysis showed clustering of spectra from malignant samples. The results show that despite a strong fluorescence signal from blood with the 532 nm laser line, spectra collected with both 532 nm and 785 nm laser lines are complementary, as they produce different high-intensity bands; e.g., breast cancer and adenocarcinoma signals are stronger with 785 nm. The main change in cancer specimens is an increase in amino acids. In addition, in small-cell carcinoma of the lung and mesothelioma, elevated nucleic acids and lipids were observed, respectively. Raman spectroscopy shows distinct profiles for control and malignant effusions. Further investigation of the utility of spectral markers in personalized treatment could improve survival.

In plain English

This laboratory study from Krakow, Poland, tested whether Raman spectroscopy can tell apart pleural effusions (fluid around the lungs) caused by different cancers. Raman spectroscopy is a laser-based method that reads the chemical makeup of a sample. The authors analyzed fluid from 20 adults with suspected cancer: five controls with non-cancerous reactive changes, four with mesothelioma, and eleven with other cancers of the lung, colon, ovary, breast and kidney. Dried samples were measured at three points each with two lasers (532 nm and 785 nm). Asbestos exposure was not studied. A statistical pattern analysis grouped the samples best using the 400 to 1720 cm−1 range of the spectrum. The two lasers gave complementary information. For example, lung adenocarcinoma and breast cancer gave strong signals in one region with the 785 nm laser but weak ones with the 532 nm laser. The authors concluded that all cancer types showed increased amino acid residues, that small-cell carcinoma had the highest DNA content, and that mesothelioma was characterized by high lipid content. They stated that a larger group is needed, and they did not perform a diagnostic (discriminant) analysis.

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 proof-of-concept study: Raman spectroscopy of pleural effusion samples, analyzed with Principal Component Analysis
• Who was studied: 20 adult patients with clinical suspicion of malignancy at a thoracic surgery department in Krakow, Poland (9 females, 11 males; average age 71, range 57–88), collected over approximately one year. Groups: 5 controls (reactive changes), 4 mesotheliomas, 3 lung adenocarcinomas, 1 colon adenocarcinoma, 2 squamous lung carcinomas, 2 ovarian serous carcinomas, 1 small-cell lung carcinoma, 1 breast carcinoma, 1 renal cell carcinoma
• Exposure: No asbestos or other environmental or occupational exposure was studied. The study measured the chemical (spectral) profile of pleural fluid by tumor type. Asbestos minerals such as crocidolite appear only in the discussion, as the subject of other studies.
• Main results:
  • Across the samples, bands in the high-number region were more intense with the 532 nm laser, and bands in the fingerprint region were more intense with the 785 nm laser. Blood fluorescence signals appeared with the 532 nm laser.
  • Principal Component Analysis of three spectra from each of the 20 patients clustered the groups best in the fingerprint region (400–1720 cm−1), for both lasers.
  • With the 532 nm laser, the first three components explained 62.5%, 22.5% and 5.4% of the variance. The first component separated squamous lung carcinoma and small-cell carcinoma from the other groups.
  • Mesothelioma samples (4 patients) had a low-intensity signal in the fingerprint region. With the 532 nm laser, the third principal component was higher for mesothelioma than for the control group.
  • With the 532 nm laser, the third principal component was higher for mesothelioma than for controls.
  • Lung adenocarcinoma and breast carcinoma gave high-intensity signals in the high-number region with the 785 nm laser but low ones with the 532 nm laser. The authors said the reason is unclear.
  • With the 785 nm laser, the second principal component was low for mesothelioma and high for ovarian carcinoma, small-cell carcinoma and squamous carcinoma.
• The authors' conclusion: The authors concluded that all malignancy types investigated were characterized by increased amino acid residues, that small-cell carcinoma had the highest DNA content, and that mesothelioma was characterized by high lipid content. They also concluded that the 785 nm laser is likely preferable for samples with low organic matter and blood content, and that Raman spectroscopy holds potential for diagnosing malignant pleural effusions.
• Limitations the authors state:
  • Some effusion types are rare, so it was difficult to collect similar numbers of samples for each type.
  • A discriminant analysis for diagnostic use should be done on a larger group, and none was performed in this study.
  • Planned tissue measurements were discontinued because of small sample size and necrosis.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Adenocarcinoma, Carcinoma, Mesothelioma.

Related studies

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• EPR, optical, infrared and Raman spectral studies of Actinolite mineral — N.O. Gopal, K.V. Narasimhulu, et al. (2004)
• Application of portable Raman instruments for fast and non-destructive detection of minerals on outcrops — J. Jehlicka, P. Vítek, et al. (2009)
• Optical detection and grading of lung neoplasia by Raman microspectroscopy — P.R. Jess, M. Mazilu, et al. (2009)
• IMP3/L523S, a novel immunocytochemical marker that distinguishes benign and malignant cells: the expression profiles of IMP3/L523S in effusion cytology — K. Ikeda, G. Tate, et al. (2010)
• Profile of soluble factors in pleural effusions predict prognosis in mesothelioma — I.M. Dick, Y.C.G. Lee, et al. (2022)

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