Analysis of Normal and Cancer Tissue in the Stomach Using Raman Spectroscopy

ABSTRACT

PURPOSE: Raman spectroscopy is a vibrational spectroscopic technique, which is capable of providing details on the chemical composition, molecular structure and molecular interactions in cells and tissues. The primary objective of this study was to explore Raman spectroscopy for the detection of spectral changes between normal and cancer tissue in the stomach. METHODS: Tissue specimens were obtained from the resected stomach of advanced gastric cancer patients. The normal gastric and cancer tissues were harvested from the middle, lower portion of the stomach and from the tumor mass, respectively. 19 sets (antrum, body and cancer) of spectral data, with clearly defined histopathological findings, were selected in this study. FT-Raman spectroscopy (Bruker Inc., Karsruhe, Germany) was used for tissue Raman studies, with excitation at 1, 064 nm. The Raman spectra from the gastric tissue specimens were obtained with a 20 minute signal acquisition time. RESULTS: In the range 700~1, 900 cm-1, the Raman spectra of gastric antral tissue were dominated by a number of vibrational modes of biomolecules, such as proteins, lipids and nucleic acids. The Raman spectrum pattern of gastric body tissue was similar to that of the antrum, suggesting the structure and composition between the gastric antrum and body are much the same. The Raman spectra differed significantly between the normal and malignant cancer tissues, with cancers showing higher percentage signals for protein, lipid and nucleic acid compared to normal tissue (P<0.05). Difference were observed in the shapes of the Raman spectra between the normal and cancer tissues, particularly in the spectral ranges 1, 250~1, 255, 1, 330~1, 340 and 1, 440~1, 450 cm-1, which contain signals relating to protein and lipid conformations and CH2 bending mode of nucleic acids. CONCLUSION: This study demonstrates the ability of Raman spectroscopy to detect biochemical changes in malignant gastric tissue, and may become a useful adjunct to pathological diagnosis allowing guided biopsies and assessment of adequacy of resection margins.