The objective of the proposed research is to develop new diagnostic modalities based on optical spectroscopy (auto fluorescence, absorption, and scattering) for the diagnosis of breast cancer and test its performance as an adjunct to core needle biopsy. For the surgery part of the study, all patients scheduled to have a mastectomy or lumpectomy for the treatment of breast cancer will be asked if they would be willing to participate in this study. For the core needle biopsy part of the study, patients with a higher pre-probability of cancer (based on mammography) will be recruited to increase the number of patients with malignant lesions and enrolled in this investigation.