Potential Application of Raman Spectroscopy for Real-time Diagnosis and Classification of Colorectal Cancer

Abstract

Raman spectroscopy has become a remarkable tool for real-time detection and diagnosis of various cancers. We investigated whether Raman spectroscopy can be used to diagnose colorectal cancer. Samples of cancerous and non-cancerous tissues were obtained from 12 patients undergoing surgery for such cancer. A handheld Raman spectrometer employing an excitation wavelength of 1,064nm was used at 94 points: 48 points on cancerous tissues and 46 points on normal tissues. Using principal component analysis （PCA）, we selected 12 PCs from the Raman spectra obtained at each of the 94 observed points. We then used linear discriminant analysis （LDA） to distinguish cancer from normal tissues and early cancer from advanced cancer, and we calculated sensitivity, specificity, and accuracy of the Raman spectroscopy for such diagnoses. We immediately confirmed that there was no local temperature rise, color change, or damage at the irradiated points, and we found that Raman spectroscopy was able to distinguish cancer from normal tissues with a sensitivity of 87.5％, specificity of 82.6％, and accuracy of 85.1％. In addition, Raman spectroscopy distinguished early cancer from advanced cancer with a sensitivity of 85.7％, specificity of 83.3％, and accuracy of 85.4％. Thus, near-infrared Raman spectroscopy shows potential as an objective, rapid, non-invasive diagnostic modality for colorectal cancer.