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

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.