Systems and methods for spectral analysis of a tissue mass using an instrument, an optical probe, and a Monte Carlo algorithm or a diffusion algorithm are provided. According to one method, an instrument is inserted into a tissue mass. A fiber optic probe is applied via the instrument into the tissue mass. Turbid spectral data of the tissue mass is measured using the fiber probe. The turbid spectral data is converted to absorption, scattering, and/or intrinsic fluorescence spectral data via a Monte Carlo algorithm or diffusion algorithm. Biomarker concentrations in the tissue mass are quantified using the absorption, scattering, and/or intrinsic fluorescence spectral data.
