To improve rectal cancer management, there is a need for better visualization of drug targets in rectal cancer to identify patients who might benefit from specific targeted treatments. Molecular imaging of rectal cancer associated targets is a promising technique to accommodate this need. Vascular Endothelial Growth Factor (VEGF), which is differentially expressed in normal versus malignant colon tissue, has proven to be a valid target for molecular imaging. Fluorescent labeling of bevacizumab (a VEGF targeting humanized monoclonal antibody currently used in anti-cancer therapy) using IRDye800CW (a fluorescent dye) has potential advantages in view of safety, infrastructure, costs, stability and imaging resolution. Therefore, the fluorescent tracer bevacizumab-IRDye800CW has been developed at the University Medical Center Groningen (UMCG) and was recently approved to be administered to patients in a tracer dose. To detect this tracer in vivo in patients with colorectal cancer, a newly developed flexible near-infrared (NIR) fluorescence endoscope and optoacoustic endoscope have been developed which can be used in clinical studies. Optical fluorescence imaging may support response evaluation following chemoradiotherapy and give insight which patient might benefit from anti-VEGF targeted therapy in future studies.