NEO: Neoadjuvant Chemotherapy, Excision and Observation for Early Rectal Cancer

Inclusion Criteria: * Histologically confirmed invasive well-moderately differentiated rectal adenocarcinoma diagnosed within 90 days prior to enrollment. * Tumour stage cT1-T3abN0 based on pelvic MRI * cT1N0- tumour invasion into submucosa, no radiographic evidence of mesorectal nodal metastasis, tumour deposits or vascular invasion. * cT2N0 - tumour invasion into muscularis propria, no radiographic evidence of mesorectal nodal metastasis, tumour deposits or vascular invasion. * cT3a,bN0- tumour invasion through the muscularis propria no more than 5 mm into the subserosa/perirectal tissue and clear of the circumferential radial margin (CRM). Absence of radiographic evidence of mesorectal nodal metastasis, tumour deposits or lymphovascular invasion. Note: If the tumour is not visualized in the MRI but there is histological confirmation of rectal adenocarcinoma the patient is eligible. * cN0 stage based on pelvic MRI. Any nodes ≥ 10 mm in longest dimension are considered malignant, regardless of nodal morphology. For pelvic nodes \< 10 mm in longest dimension, if nodes are seen and are deemed to be morphologically benign in the opinion of the radiologist and surgeon, the patient is eligible. Patients with visible pelvic sidewall nodes are excluded * M0 stage based on no evidence of metastatic disease by CT imaging. * Mid to low-lying tumour eligible for local tumour excision in the opinion of the treating surgeon. * Age of at least 18 years. * Medically fit to underg…