Near-Infrared Multichannel Raman Spectroscopy with a 1064 nm Excitation Wavelength for Ex Vivo Diagnosis of Gastric Cancer

Abstract

Gastric cancer is one of the major causes of death in Japan. We have previously reported, using biopsy specimens, the usefulness of the 1064 nm near-infrared multichannel Raman spectroscopy (RAS) system as a novel diagnostic modality for gastric cancer. However, our study might not have reflected invivo use of RAS due to a lack of tissue other than the mucosal layer in the biopsy specimens. Here, we used RAS exvivo for optical diagnosis of gastric cancer in surgically resected stomach. A total of 213 Raman spectra were obtained from 12 cancer lesions and their corresponding non-neoplastic areas in 10 stomachs following resection for gastric cancer. To develop optical diagnostic systems for gastric cancer, principal component analysis (PCA) of all the Raman spectra was performed. The averaged Raman spectra of the cancer lesions could be distinguished from those of the non-neoplastic regions. Discrimination analysis of cancer from non-neoplastic regions with 10 principal components revealed that sensitivity, specificity, and accuracy of cancer diagnosis were 73%, 73%, and 72%, respectively. RAS discriminated between differentiated and undifferentiated cancers, early and advanced cancers, as well as T1a (M) and T1b (SM) cancers with high accuracy (98%, 93%, and 98%, respectively). The 1064 nm near-infrared multichannel RAS system is useful not only for gastric cancer detection, but also for discrimination between differentiated and undifferentiated, as well as early and advanced cancers. RAS could help establish indications for endoscopic treatment by eliminating cancer lesions with an undifferentiated component or submucosal invasion.