Evaluation of in vivo endoscopic autofluorescence spectroscopy in gastric cancer.

BACKGROUND: The aim of this study was to evaluate light-induced autofluorescence spectroscopy for the in vivo diagnosis of gastric cancer. METHODS: A total of 344 endogenous fluorescence spectra were obtained from normal (164) and cancerous gastric mucosa (180) in 15 patients with pure adenocarcinoma and in 16 patients with gastric cancer containing signet-ring cells. A special light source capable of delivering either white or violet-blue light for the excitation of tissue autofluorescence via the endoscope was used. Endogenous fluorescence spectra emitted by the tissue were collected with a fiberoptic probe and analyzed with a spectrograph. RESULTS: Gastric adenocarcinoma exhibits specific changes in the emitted fluorescence spectra as compared with normal gastric mucosa. By algorithmic classification of the spectra, a sensitivity of 84%, specificity of 87%, a likelihood ratio for a positive test of 6.5 and for a negative test of 0.18 were obtained for the diagnosis of pure adenocarcinoma of the stomach. However, gastric cancer with signet-ring cells exhibits great variation in emitted autofluorescence spectra as compared with normal mucosa. The sensitivity for the diagnosis of all carcinomas containing signet-ring cells was 55%, specificity 85%, the likelihood ratio for a positive test was 3.7 and for a negative test, 0.53. The diagnostic value decreases with increasing numbers of signet-ring cells and tumor grade. CONCLUSIONS: Light-induced autofluorescence spectroscopy is a new and promising bio-optical technique for the endoscopic in vivo diagnosis of gastric adenocarcinoma. The poor diagnostic accuracy for signet-ring cell carcinoma may be explained by the diffuse and frequent submucosal growth of this tumor and the presence of collagen fibers.

Endoscopic light-induced autofluorescence spectroscopy for the diagnosis of colorectal cancer and adenoma.

To evaluate the new, bio-optical method of light-induced autofluorescence spectroscopy for the endoscopic in-vivo diagnosis of (pre)-cancerous lesions of the colorectum, 311 endogenous fluorescence spectra were obtained from normal, adenomatous and cancerous colorectal tissue in 11 patients with cancer, six patients with familial adenomatous polyposis, and six patients with multiple adenomatous polyps. A light source delivered either white or violet-blue light for excitation of tissue autofluorescence via a flexible endoscope. Endogenous fluorescence spectra emitted by the tissue were picked up with a fiberoptic probe and analysed with a spectrograph. Biopsies were taken for definitive classification of the spectra. Rectal cancer (n=11) as well as adenomas with severe dysplasia (n=19) showed specific differences between the emitted fluorescence spectra as compared with normal mucosa and hyperplastic polyps. Having applied a mathematical algorithm to the spectra, a sensitivity of 96% and a specificity of 93% were obtained for the diagnosis of rectal cancer. The equivalent values for the diagnosis of dysplastic ademomas were 98 and 89%, respectively. Light-induced autofluorescence spectroscopy is a new and promising bio-optical procedure for the endoscopic in-vivo diagnosis of colorectal cancer and dysplasia.