All patients with recurrent colorectal cancer in the pelvis are eligible. The original primary tumour staging scans and resected surgical specimen needs to be available. Patients' recurrence will be staged using our proposed MRI classification. We will be assessing the original primary staging scans and histopathology to learn about risk factors for recurrence. We will record treatment for the recurrence, and patients will be followed up for three years.

A prospective and retrospective cohort study to improve surgical and treatment planning using an imaging assessment proforma of advanced and recurrent colorectal cancers. This involves the implementation of imaging assessment proformas describing anatomic pelvic compartments and aetiology of disease recurrence for treatment planning.

Inclusion Criteria:

1. Had a primary colorectal adenocarcinoma proven by biopsy taken as part of routine clinical practice
2. Has a confirmed diagnosis of recurrent pelvic colorectal cancer
3. Has previously completed surgical treatment of primary adenocarcinoma of the colon, sigmoid colon or rectum
4. Are able to undergo high resolution MRI for staging prior to treatment decisions
5. Have provided written informed consent to participate in the study
6. Be aged 16 years or over

Exclusion Criteria:

1. Have irresectable extra-pelvic metastatic disease
2. Original baseline staging and preoperative restaging scans (MR for rectal and sigmoid cancers and/or CT for colon and sigmoid cancers) are unavailable
3. Original preoperative, surgical and adjuvant treatment has not been documented or is unavailable