The current standard of care for rectal cancer has diminished local recurrence and enhanced survival. Quality of life, however, remains poor for many patients and the probability of distant recurrence is high. In this study, we will attempt to reduce the distant recurrence rate and improve quality of life by making changes in the timing and administration of chemotherapy and radiation and doing less invasive rectal surgery when indicated.

The purpose of the study is to determine if neo-adjuvant FOLFOX therapy and lengthening the time interval between neo-adjuvant chemotherapy and transanal local excision will increase the percentage of patients with pathologic complete remission.

This is a prospective pilot study to examine the impact of two variables: 1) addition of neo-adjuvant FOLFOX chemotherapy, and 2) increasing the time interval between completion of chemo-radiotherapy and subsequent surgery, on the rate of achieving pathologic complete remission with avoidance of radical resection while maintaining an excellent local control with improvement of quality of life.

All procedures in this study are standard of care, the study question relates to the use of neo-adjuvant FOLFOX and the timing between the end of radiation and surgery.

Inclusion Criteria:

1. Age ≥ 18 years
2. Diagnosis of rectal invasive adenocarcinoma
3. Tumor in the low or mid rectum (up to 11 cm from the anal verge)
4. Clinical stage T3/N0-N1M0. Patients with low T2 who will need abdominal perineal resection are also eligible.

1. Clinical staging will be estimated based on the combination of the following assessments:

1. Physical examination by the primary surgeon
2. Computed Tomography or Positron Emission Tomography/Computed Tomography scan of chest, abdomen and pelvis
3. Pelvic MRI and endoscopic ultrasound

Exclusion Criteria:

• Less than 18 years of age
• Do not complete informed consent
• Pregnant women