Autofluorescence spectroscopy to identify normal and cancerous colorectal tissues

The light induced autofluorescence spectroscopy was performed to identify normal and cancerous colorectal tissues. In this study, a total of 20 normal and 20 cancerous tissues were obtained from patients receiving oncological surgery of colon and rectum. We measured and analyzed the autofluorescence spectra at 280 to 400 nm excitations in 10 nm increments to search for the optimal excitation wavelength. For each sample, we calculated the “two-peak ratio” value to distinguish between normal and cancerous tissues at different excitation wavelengths. By using the Student´s t-test, we found that there are statistically significant differences in the “two-peak ratio” of the autofluorescence spectra between normal and cancerous tissues at 300, 320, 330 and 340 nm excitations (p<0.001). Furthermore, by applying the Receiver Operating Characteristic (ROC) curves, the 330 nm excitation, which yielded 85% sensitivity, 90% specificity, and 89% positive predictive value when appropriate threshold was selected, appeared to be one of the optimal excitation wavelengths among the aforementioned excitation wavelengths. The “ex vivo” study and the development of the “two-peak ratio” algorithm might be useful for developing the diagnostic algorithm for colorectal cancer in vivo