The field of biomedical optics has grown quickly over the last two decades as various technological advances have helped increase the acquisition speeds and the sensitivity limits of the technology. During this time, optical coherence tomography (OCT) has been explored for a wide number of clinical applications ranging from cardiology to oncology to primary care. In this thesis, I describe the design and construction of an intraoperative clinical OCT system that can be used to image and classify breast cancer tumor margins as normal, close, or positive. I also demonstrate that normal lymph nodes can be distinguished from reactive or metastatic lymph nodes by looking at the difference in scattering intensity between the cortex and the capsule of the node. Despite the advances of OCT in the detection and diagnosis of breast cancer, this technology is still limited by its field of view and can only provide structural information about the tissue. Structural OCT would benefit from added contrast via sub-cellular or biochemical components via the use of contrast agents and functional OCT modalities. As with most other optical imaging techniques, there is a trade off between the imaging field of view and the high-resolution microscopic imaging. In this thesis, I demonstrate for the first time that MM-OCT can be used as a complimentary technique to wide field imaging modalities, such as magnetic resonance imaging (MRI) or fluorescence imaging, using targeted multi-modal protein microspheres. By using a single contrast agent to bridge the wide field and microscopic imaging modalities, a wide field imaging technique can be used to initially localize the contrast agent at the site of interest to guide the location of the MM-OCT imaging to provide a microscopic view. In addition to multi-modal contrast, the microspheres were functionalized with RGD peptides that can target various cancer cell lines. The cancer cells readily endocytosed bound protein microspheres, revealing the possibility that these protein microspheres could also be used as therapeutic agents. These investigations furthered the utility of the OCT technology for cancer imaging and diagnosis.