Plasma-based near-infrared spectroscopy combined with aquaphotomics for colorectal cancer screening

Fast, noninvasive and cost-effective methods for screening colorectal cancer (CRC) before uncomfortable colonoscopy are highly desirable. This study aimed to explore the feasibility of using near-infrared spectroscopy (NIRS) combined with aquaphotomics for CRC screening. Forty-nine CRC patients and forty-seven healthy controls (HC) were enrolled, and their plasma samples were measured via NIRS. Aquaphotomics analysis, including principal component analysis, partial least squares discriminant analysis (PLS-DA), and difference spectra calculation, was performed to identify water matrix coordinates and form water absorption spectral patterns (WASPs) with aquagrams. The aquaphotomics results demonstrated that the PLS-DA diagnostic model with Savitzky-Golay second derivative preprocessing yielded a high predictive accuracy of 97 %, with sensitivity and specificity of 100 % and 94 % in the independent test set. The aquagrams displayed an evident shift in WASPs of CRC comparing to HC in both train and test sets. These findings reveal that combing NIRS with aquaphotomics is effective and visually interpretable, and the distinct differences between water of strong (1482 nm, 1486 nm) and weak (1429 nm, 1436 nm) hydrogen bonds in the WASPs may serve as a biomarker for CRC screening.