As a result, the optical tomography assisted with US has overcome problems associated with intense light scattering and has provided reliable tumor angiogenesis distributions. Initial results with a small group of patients who underwent biopsy have shown that early stage invasive cancers present two-fold greater total hemoglobin concentration on average than fibroadenomas and other benign lesions. Initial results of advanced cancers have shown that the angiogenesis distribution is highly distorted and heterogeneous, and the distorted distributions correlate with histological microvessel density counts and can be used to assess chemotherapy response.