Inclusion Criteria:

1. Rectal adenocarcinomas located 10 cm or less from the inferior anal verge measured
using a rigid rectoscope at the time of the EUS.

2. Preoperative staging by EUS and pelvic MRI of T2 or T3 superficial, N0. In case of
disparity, the higher staging is considered as the definitive diagnosis.

3. Tumours equal to or less than 4 cm of diameter maximum measured using colonoscopy,
EUS or MRI. We use the highest score on both scores.

4. ASA score III or less.

5. Absence of distance metastasis as shown on abdominal CT.

Exclusion Criteria:

1. Preoperative staging by EUS or pelvic MRI of T1, deep T3, T4 or N1.

2. Presence of distance metastasis.

3. Synchrony with other colorectal adenocarcinomas.

4. Undifferentiated rectal adenocarcinomas or with presence of poor prognosis factors in
preoperative biopsy.

5. Patients with intolerance of preoperative chemotherapy or radiotherapy.

6. Refusal to sign informed consent to enter the study.