MKI67 and breast cancer: Specifically, we investigated how DOT-based physiological parameters in malignant tumors, such as oxyhemoglogin, deoxyhemoglobin concentrations, tissue blood oxygenation, and tumor-to-normal ratio of the mammary metabolic rate of oxygen (rMMRO2) (derived from hemoglobin concentration and DCS blood flow data) correlate with microscopic histopathological biomarkers from the same malignant tumors, i.e., with the Ki67 proliferation marker, the CD34 stained vasculature marker, nuclear morphology and with hormonal receptor status of breast cancer.