We report an approach for determination of the scattering coefficient, the reduced scattering coefficient, and the anisotropy factor from the quantitative phase map measured by differential interference contrast microscopy based on the scatteringphase theorem. The approach is first validated by showing the excellent agreement between the retrieved optical properties of polystyrene spheres and Intralipid-20% suspension and their known values. The scattering properties of unstained pathological prostate cancer slides and fresh cancerous and normal colon tissue samples are then investigated. A clear trend with cancer in the reduced scattering coefficient and the anisotropy factor is shown. The potential of the approach for tissue diagnosis is discussed at the end.