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Lower GI: MRI risk stratification for neoadjuvant therapy

Free question published 03 August 2026

Lower GIMRI risk stratification for neoadjuvant therapy

A 58-year-old man has a mid-rectal adenocarcinoma. Staging MRI demonstrates a cT3c tumour extending more than 5 mm beyond the muscularis propria, with the tumour reaching to within 1 mm of the mesorectal fascia and unequivocal extramural venous invasion. There is no metastatic disease. The MDT is deciding whether neoadjuvant treatment is indicated. Which MRI feature is the principal driver of this decision?

  1. AA synchronous colorectal polyp identified in the sigmoid colon during preoperative imaging assessment
  2. BThe patient's carcinoembryonic antigen level
  3. CThe distance of the tumour from the anal verge
  4. DCRM at 1 mm or less with EMVI and advanced T3 substage
  5. EThe histological grade of the biopsy specimen alone

Why D is correct

The ESMO consensus guideline states that neoadjuvant treatment decisions should be based on MRI-predicted CRM (1 mm or less), EMVI and the more advanced T3 substages (T3c/T3d). A threatened mesorectal fascia with EMVI marks this tumour as high risk for local recurrence and an indication for neoadjuvant therapy, whereas a clear margin on a less advanced tumour would support primary surgery.

And why the others are not

  • AIncorrect. A synchronous sigmoid polyp does not influence the neoadjuvant decision for the rectal primary.
  • BIncorrect. CEA is a follow-up and prognostic marker; it does not drive the MRI-based neoadjuvant decision.
  • CIncorrect. Height from the verge informs surgical planning and sphincter preservation but is not the principal MRI determinant of neoadjuvant therapy in the ESMO framework.
  • EIncorrect. Histological grade contributes to overall risk but is not the MRI feature the ESMO consensus identifies as the principal driver.

Source ESMO Consensus Guidelines — management of rectal cancer (MRI risk stratification) — Glynne-Jones R, Wyrwicz L, Tiret E, et al. Rectal cancer: ESMO Clinical Practice Guidelines / ESMO Consensus Guidelines for management of patients with colon and rectal cancer. Ann Oncol.

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