Pilot Study of Advanced MR Imaging for Early Biologic Tumor Changes to Neoadjuvant Chemoradiation Treatment for Rectal Cancer

This is a pilot study of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI, aka perfusion MRI) and diffusion-weighted MRI (DWI-MRI), herein referred to in combination as advanced MRI (aMRI) in the investigation of early tumor response to standard multi-dose, fractionated external beam radiotherapy (EBRT) of the pelvis given in the neoadjuvant setting concurrent with chemotherapy as well as induction chemotherapy prior to chemoradiotherapy or consolidation chemotherapy after chemoradiotherapy for primary rectal adenocarcinoma. This protocol aims to expand upon the growing body of knowledge concerning early changes in tumor neovascularity and cellular density as a potential biomarker of therapy efficacy. It further aims to address the trend towards more refined treatment stratification for lower risk tumors to avoid morbidity from potentially unnecessary radiation, chemotherapy or even radical surgery, by assessing the earliest changes that occur in microvasculature and perfusion and diffusion of water during this treatment to see if these can be predictive of long-term efficacy of therapy.