Insights into Biochemical Sources and Diffuse Reflectance Spectral Features for Colorectal Cancer Detection and Localization

SIMPLE SUMMARY: Colorectal cancer (CRC) is the third most common and second most deadly type of cancer worldwide. The early detection and accurate characterization of colorectal cancer are associated with improved outcomes. With increasing emphasis on early cancer detection and the use of minimally invasive microsurgical techniques, the development of accurate diagnostic technologies to identify tumors and define their boundaries in real time becomes of paramount importance. The current research identifies potential cancer biomarkers and associated light-based instrument specifications to manufacture next-generation medical devices for CRC detection. These specifications have been chosen so that miniaturized instruments can be integrated into colonoscopes. Cancer biomarkers are listed to enable the use of complementary biochemical methods to analyze biological tissues. The impact of using next-generation colonoscopes in reducing cancer deaths can be assessed once medical devices are manufactured. ABSTRACT: Colorectal cancer (CRC) is the third most common and second most deadly type of cancer worldwide. Early detection not only reduces mortality but also improves patient prognosis by allowing the use of minimally invasive techniques to remove cancer while avoiding major surgery. Expanding the use of microsurgical techniques requires accurate diagnosis and delineation of the tumor margins in order to allow complete excision of cancer. We have used diffuse reflectance spectroscopy (DRS) to identify the main optical CRC biomarkers and to optimize parameters for the integration of such technologies into medical devices. A total number of 2889 diffuse reflectance spectra were collected in ex vivo specimens from 47 patients. Short source-detector distance (SDD) and long-SDD fiber-optic probes were employed to measure tissue layers from 0.5 to 1 mm and from 0.5 to 1.9 mm deep, respectively. The most important biomolecules contributing to differentiating DRS between tissue types were oxy- and deoxy-hemoglobin (Hb and HbO(2)), followed by water and lipid. Accurate tissue classification and potential DRS device miniaturization using Hb, HbO(2), lipid and water data were achieved particularly well within the wavelength ranges 350–590 nm and 600–1230 nm for the short-SDD probe, and 380–400 nm, 420–610 nm, and 650–950 nm for the long-SDD probe.