The purpose of this study was to comparatively analyze the signature Raman spectra of genomic DNA, nuclei, and tissue of normal gastric mucosa and gastric cancer and to investigate the biochemical transformation of molecules associated with gastric mucosa malignancy. Genomic DNA, nuclei, and tissue from normal gastric mucosa and gastric cancer were analyzed by Raman spectroscopy. 1) The Raman spectrum of gastric cancer genomic DNA showed that two peaks appeared, one at approximately 1090 cm^-1 with a higher intensity than the peak at 1050 cm^-1 in the spectrum. Characteristic peaks appeared at 950 cm^-1, 1010 cm^-1, and 1100-1600 cm^-1. 2) Using a hematoxylin and eosin (H&E)-stained section, the intensity of the characteristic peak of nucleic acids at 1085 cm^-1 was increased and shifted to 1088 cm^-1 in cancer cells. The relative intensity of the characteristic peaks of nucleoproteins at 755 cm^-1 and 1607 cm^-1 was significantly increased in cancer cells compared with normal cells. 3) Compared with normal tissues, the peak representing PO^2- symmetric stretching vibration shifted from 1088 cm^-1 to 1083 cm^-1 in cancer tissue, and the characteristic peak for collagen at 938 cm^-1 shifted to 944 cm^-1. In addition, an extra characteristic peak indicating C = C stretching vibration appeared at 1379 cm^-1 in the lipid spectrum in cancer tissue. The position, intensity, and shape of peaks in the Raman spectra of DNA, nuclei, and tissue from gastric cancer were significantly different compared with those of normal cells. These results indicate that the DNA phosphate backbone becomes unstable in cancer cells and might be broken; the relative content of histones is increased and stable; the relative collagen content is reduced, facilitating cancer cell metastasis; and the relative content of unsaturated fatty acids is increased, increasing the mobility of the plasma membrane of cancer cells.

A fiber-optic Raman spectrum sensor system is used for the fast diagnosis of esophageal cancer during clinical endoscopic examination. The system contains a 785 nm exciting laser, a Raman fiber-optic probe with 7 large core fibers and a focus lens, and a highly sensitive spectrum meter. The Raman spectrum of the tissue could be obtained within 1 second by using such a system. A signal baseline removal and denoising technology is used to improve the signal quality. A novel signal feature extraction method for differentiating the normal and esophageal cancer tissues is proposed, based on the differences in half-height width (HHW) in 1200 cm^‒1 to 1400 cm^‒1 frequency band and the ratios of the spectral integral energy between 1600 cm^‒1 − 1700 cm^‒1 and 1500 cm^‒1 − 1600 cm^‒1 band. It shows a high specificity and effectivity for the diagnosis of esophageal cancer.

Objective. To evaluate the accuracy of double vital staining with lugol's iodine and methylene blue in the diagnosis of superficial esophageal lesions. Methods. Doubtful superficial esophageal lesions identified with conventional endoscope were sprayed with 3% lugol's iodine and 0.5% methylene blue in order and observed in detail after each staining. Depending on the mucosal staining, biopsy specimen was obtained and underwent pathological examination. Results. Using conventional endoscope, we found 356 lesions in 297 patients, among which 179 were esophageal squamous cell carcinoma and precancerous lesions (CAPs) (including 71 early esophageal squamous cell carcinoma, 23 esophageal high-grade intraepithelial neoplasias, 85 esophageal low-grade intraepithelial neoplasias) and 177 were non-cancer non-precancerous lesions (NCNPs) (i.e. esophagitis and esophageal squamous cell hyperplasia). Most of CAPs were lightly stained or unstained, while NCNPs were hyperstained after lugol's iodine stained. The specificity, sensitivity, positive predictive value, negative predictive value and accuracy of lugol's lightly stained and unstained for identifying CAPs were 34.5%, 100%, 60.7%, 100% and 67.4%, respectively. Most of CAPs were lightly stained or hyperstained, while NCNPs were unstained after double vital staining. The specificity, sensitivity, positive predictive value, negative predictive value and accuracy of double vital staining lightly stained and hyperstained for identifying CAPs were 97.7%, 100%, 97.8%, 100% and 98.9%, respectively. The accuracy of double vital staining for identifying CAPs was higher than that of lugol's iodine stained (p = 0.000). Conclusion. The double staining with lugol's iodine and methylene blue significantly improves the detection and diagnosis of early esophageal squamous cell CAPs.

Aim. To identify lesional and nonlesional tissues from early gastric cancer (EGC) patients by Raman spectroscopy to build a diagnostic model and effectively diagnose EGC. Method. Specimens were collected by endoscopic submucosal dissection from 13 patients with EGC, and 55 sets of standard Raman spectral data (each integrated 10 times) were obtained using the fiber optic Raman system; there were 33 sets of lesional tissue data, including 18 sets of high-grade intraepithelial neoplasia (HGIN) data and 15 sets of adenocarcinoma data, and 22 sets of nonlesional tissue data. After the preprocessing steps, the average Raman spectrum was obtained. Results. The nonlesional tissues showed peaks at 891 cm^-1, 1103 cm^-1, 1417 cm^-1, 1206 cm^-1, 1234 cm^-1, 1479 cm^-1, 1560 cm^-1, and 1678 cm^-1. Compared with the peaks corresponding to nonlesional tissues, the peaks of the lesional tissues shifted by different magnitudes, and a new characteristic peak at 1324 cm^-1 was observed. Comparing the peak intensity ratio and the integral energy ratio of the lesional tissues with those of the nonlesional tissues revealed a significant difference between the two groups (independent-samplest-test, P<0.05). Considering the peak intensity ratio of I1560 cm^-1/I1103 cm^-1 as a diagnostic indicator, the accuracy, sensitivity, and specificity of diagnosing EGC were 98.8%, 93.9%, and 91.9%, respectively. Considering the integral energy ratio (noncontinuous frequency band and continuous frequency band) as a diagnostic indicator, the accuracy, sensitivity, and specificity of diagnosing EGC were 99.2-99.6%, 93.9-97.0%, and 95.5%, respectively. Conclusions. The integral energy ratio of the Raman spectrum could be considered an effective indicator for the diagnosis of EGC.