Patients will undergo 50.4 to 54Gy of radiation in 1.8Gy daily fractions delivered Monday through Friday for a total of 28-30 fractions. The acceptable duration of chemoradiation, including treatment breaks or delays, is up to 8 weeks total. Six to ten weeks after completing their neoadjuvant therapy, patient will undergo a tumor specific mesorectal excision as per standard of care with evaluation of pathologic response rate. Patients will be followed for disease-free survival, progression free survival, local recurrence, and overall survival. A three patient safety lead-in will be performed, where a six week safety period following completion of radiation will be completed prior to enrolling subsequent patients.