Raman spectroscopy for the diagnosis of unlabeled and unstained histopathological tissue specimens

AIM: To investigate the possibility of diagnosing gastric cancer from an unstained pathological tissue using Raman spectroscopy, and to compare the findings to those obtained with conventional histopathology. METHODS: We produced two consecutive tissue specimens from areas with and without cancer lesions in the surgically resected stomach of a patient with gastric cancer. One of the two tissue specimens was stained with hematoxylin and eosin and used as a reference for laser irradiation positioning by the spectroscopic method. The other specimen was left unstained and used for Raman spectroscopy analysis. RESULTS: A significant Raman scattering spectrum could be obtained at all measurement points. Raman scattering spectrum intensities of 725 cm(-1) and 782 cm(-1), are associated with the nucleotides adenine and cytosine, respectively. The Raman scattering spectrum intensity ratios of 782 cm(-1)/620 cm(-1), 782 cm(-1)/756 cm(-1), 782 cm(-1)/1250 cm(-1), and 782 ​​cm(-1)/1263 cm(-1) in the gastric adenocarcinoma tissue were significantly higher than those in the normal stomach tissue. CONCLUSION: The results of this preliminary experiment suggest the feasibility of our spectroscopic method as a diagnostic tool for gastric cancer using unstained pathological specimens.