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

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

All-in-one Raman spectroscopy approach to diagnosis of colorectal cancer: analysis of spectra in the fingerprint regions

Objectives: Raman spectroscopy yields precise information, not only regarding the secondary structure of proteins but also regarding the discrimination between normal and malignant tissues. There is, however, no standard measurement method. We evaluated the use of a miniaturized, handheld, all-in-one Raman spectrometer with a 1064-nm laser excitation source for the diagnosis of colorectal cancer. The ultimate goal is real-time, in vivo diagnosis. Methods: Tissue samples were obtained from 20 patients who underwent surgery for colorectal cancer. The samples were irradiated with the portable Progeny™ Raman spectrometer, with which the Raman spectra were also obtained. We searched for characteristic Raman shifts and examined whether these shifts could distinguish the cancer tissues. To improve accuracy, we divided the spectra into 100 cm−1 bands and applied principal component analysis (PCA) to each range. We evaluated the contribution of each range for cancer discrimination. Results: Intensities at 1261 and 1427 cm−1 differed significantly between the normal tissues and cancer tissues, but these did not efficiently discriminate the cancer tissues. However, we were able to identify the characteristic spectral range in fingerprint regions; accuracy was 85.1%. Conclusions: Use of the all-in-one type Raman spectrometer can efficiently discriminate colorectal cancer, not on the basis of the intensities at 1261 and 1427 cm−1 but rather on the basis of PCA. Thus, Raman spectroscopy performed using a handheld device has potential to become a clinically powerful tool for producing high-quality data, obtaining highly reproducible measurements, and thus accurately diagnosing colorectal cancer