The circular polarization (CP) of light scattered by biological tissues provides valuable information about the structural changes in tissues. We investigate the spatial discrimination of cancer using CP light scattering within the in-plane and along the depth direction. In-plane spatial resolution was investigated using experiments on sliced biological tissues, which show a noticeable difference in polarization values between healthy and cancerous parts in a wide angular range. The resolution in the depth direction is examined with the Monte Carlo calculation method on pseudo-tissues having thin cancerous layers on healthy tissues. The calculation results suggest that the thickness of cancer can be estimated by detecting the degree of circular polarization values with different detection angles. The in-plane and depth resolutions are approximately 0.3 mm and 0.6 mm, respectively.