Background: Gastric cancer is one of the most common cancers in Japan. The use of endoscopy is increasing, along with the number of histological examinations of specimens obtained by endoscopy. However, it takes several days to reach a diagnosis, which increases the medical expense. Raman spectroscopy is one of the available optical techniques, and the Raman spectrum for each molecule and tissue is characteristic and specific. The present study investigated whether Raman spectroscopy can be used to diagnose gastric cancer.
Methods: A total of 251 fresh biopsy specimens of gastric carcinoma and non-neoplastic mucosa were obtained from 49 gastric cancer patients at endoscopy. Without any pretreatment, the fresh specimens were measured with a near-infrared multichannel Raman spectroscopic system with an excitation wavelength of 1064 nm, and Raman spectra specific for the specimens were obtained. A principal component analysis (PCA) was performed to distinguish gastric cancer and non-neoplastic tissue, and a discriminant analysis was used to evaluate the accuracy of the gastric cancer diagnosis.
Results: The Raman spectra for cancer specimens differed from those for non-neoplastic specimens, especially at around 1644 cm(-1). Sensitivity was 66%, specificity was 73%, and accuracy was 70%. The accuracy of diagnosis using the single Raman scattering intensity at 1644 cm(-1) was 70%, consistent with the PCA result.
Conclusions: The present results indicate that near-infrared multichannel Raman spectroscopy with a 1064-nm excitation wavelength is useful for gastric cancer diagnosis. Establishment of a Raman diagnostic system for gastric cancer may improve the clinical diagnosis of gastric cancer and be beneficial for patients.