Optical Coherence Tomography (OCT) is an emerging optical technology that has shown great promise for early cancer detection. Using backreflected light to visualize tissue microstructure, OCT can provide information on nuclear size and shape, nuclear-to-cytoplasmic ratio, and the organization and structure of glands. It can also provide functional information, like blood flow, tissue birefringence, etc. These capabilities could potentially be employed in three ways: as a primary diagnostic test to replace biopsy, as a screening tool to direct biopsy, and as a diagnostic tool to guide therapy and monitor therapy response. In this paper we present an application of OCT for pancreatic cancer diagnosis and therapy guidance.