Clinical Research Directory

Inclusion criteria: To be eligible to participate in this study, a patient must meet all of the following criteria: * Adult patients (≥ 18 years of age). * Suspected rectal D-SMIC based on optical diagnosis using narrow-band imaging: * Hiroshima C2/3, JNET 3, NICE III, Kudo Vn pit pattern. * The presence of non-lifting together with features of superficial submucosal invasion (Hiroshima C1, JNET 2B, Kudo Vi pit pattern). * MRI shows cT1-T2 invasion and minimum of 1 mm preserved muscularis propria. * Tumour with its lower border situated on or below the level of the sigmoid take off as shown on rectal MRI. * Staging rectal MRI confirms absence of suspicious malignant mesorectal lymph nodes, defined as mucinous lymph nodes, perirectal lymph nodes \>9 mm in short-axis diameter, or ≥7 mm for lateral lymph nodes (classified as certain cN+), or 5-9 mm peri-rectal lymph nodes with at least 2 suspect morphological features: round shape, heterogeneity and/or irregular borders (classified as doubtful cN+). * Staging rectal MRI confirms absence of tumour deposits. * Staging rectal MRI confirms absence of extramural vascular invasion (EMVI). Exclusion criteria: A patient who meets one or more of the following criteria will be excluded from participation in this study: * Lesions involving more than 50% of the circumference. * Total lesion size larger than 6 cm. * Prior endoscopic or surgical resection attempts of the tumour. * Recurrent cancer after previous surgical or endoscopic local resection. * Severe pre-existing faecal incontinence with impaired quality of life. * Inflammatory bowel disease (IBD) with previous inflammation of the rectum. * Previous pelvic irradiation or neoadjuvant therapy. * Poor general health that prevents the use of general anaesthesia. * Inability or contraindication to undergo MRI scan. * Concomitant malignancies or other severe medical conditions that, in the opinion of the multidisciplinary team (MDT), are likely to result in death within 5 years. * AJCC stage II, III or IV CRC within the last 5 years or synchronous CRC. * Inability to complete questionnaires or sign informed consent. * Known pregnancy.