Abstract: The present invention uses spectroscopic tissue volume measurements using non-ionizing radiation to detect pre-disease transformations in the tissue, which increase the risk for this disease in mammals. The method comprises illuminating a volume of selected tissue of a mammal with light having wavelengths covering a pre-selected spectral range, detecting light transmitted through, or reflected from, the volume of selected tissue, and obtaining a spectrum of the detected light. The spectrum of detected light is then represented by one or more basis spectral components, an error term, and an associated scalar coefficient for each of the basis spectral components. The associated scalar coefficient is calculated by minimizing the error term.