Preoperative chemoradiation therapy is the preferred initial treatment option for distal rectal cancers. However, assessing tumor response to preoperative chemoradiation therapy remains a challenge to the colorectal surgeon, especially when determining if there is a complete response, observed in more than 10% of cases. The purpose of this study is to evaluate the use of the PET/CT in assessing distal rectal tumor response to preoperative chemoradiation therapy.