Preoperative ChemoRadiation And FOLFOXIRI for Rectal Cancer (CRAFTER) for Rectal Cancer

To evaluate the safety and preliminary efficacy of Preoperative ChemoRadiation and FOLFOXIRI To Escalate Complete Response for Rectal Cancer patients. receive the experimental combination of drugs (chemoradiation (capecitabine and radiation) + FOLFOXIRI (Oxaliplatin, leucovorin, irinotecan, and fluorouracil) and undergo laboratory tests and study procedures on specified days during the study period, complete end of study evaluations and tests, and participate in post-study follow up every three months for three to four years.