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Rectal cancer — multidisciplinary treatment
In locally advanced rectal cancer all non-surgical therapy is given before surgery (TNT), followed by TME resection or close surveillance when there is a complete clinical response; pelvic MRI sets the stage and the circumferential margin.
Why it matters in the exam
The radiation part of the bank asks a lot about the rectum: the advantage of pelvic MRI, what the German trial showed on preoperative versus postoperative therapy, what the Dutch trial showed on short-course radiation, and how a low tumour near the sphincter is treated. The stem gives the height from the anal verge, the T and N stage and the status of the mesorectal fascia margin.
There are also questions on dMMR rectal tumours, in which immunotherapy alone produced a complete response in almost all patients in a phase 2 trial, and on the watch-and-wait approach that preserves the sphincter and avoids surgery.
Key points
- Pelvic MRI sets the T and N stage and the distance to the mesorectal fascia.
- T3–T4 or node-positive: TNT then TME, or surveillance after a complete response.
- Short-course 25 Gy in 5 fractions and chemoradiation 50.4 Gy in 28 fractions are the two options.
- Preoperative therapy beats postoperative for local relapse and toxicity, with no survival difference.
- In dMMR rectal cancer start with immunotherapy, which achieved complete responses that allowed omitting surgery and radiation and preserving quality of life.
Summary table
| Situation | Treatment | Exam detail |
|---|---|---|
| T1–T2 N0 | TME surgery alone (low anterior or abdominoperineal resection) | Small low-risk T1 — local excision is possible |
| T3–T4 or node-positive | TNT: short-course 25 Gy in 5 fractions followed by chemotherapy, or chemoradiation 50.4 Gy in 28 fractions with capecitabine plus chemotherapy | Then TME, or close surveillance after a complete response |
| Threatened mesorectal fascia margin on MRI | Long preoperative treatment to shrink the tumour | Circumferential margin involvement is the key risk factor for local relapse |
| dMMR or MSI-high | Immunotherapy (dostarlimab) before any other treatment | Complete responses that allowed omitting surgery and radiation |
| Complete clinical response | Close surveillance with examination, endoscopy and MRI | Sphincter preservation; local regrowth is treated with salvage surgery |
| Trial findings | German: preoperative beats postoperative for local relapse and toxicity; Dutch: short-course radiation reduces local relapse | No overall survival difference in either |
| Treatment complications | After low anterior resection: LARS with urgency, frequency and faecal incontinence | After pelvic radiation: loss of fertility and sexual function, and pelvic fractures in older age |
A free exam question
בסרטן רקט ום, האם היה יתרון להעלאת מנת הקרינה הנאו- אדג'ובנטית מ- 45Gy ל- 54Gy ? (the question as examined, in Hebrew)
- א. כן .העלאת המנה הביא לשיפור במספר מדדים כולל הישרדות כוללת
- ב. לא, אמנם העלאת המנה הביאה לשיפור בשליטה המקומית, אך לא נראה יתרון בהישרדו ת , אשר מצדיק את הרעילות המוגברת
- ג. כן נראתה עליה בשיעו ר ה- pathological complete response וירידה במעורבות שוליים רדיאליים בניתוח, ללא שיפור בהישרדות
- ד. לא היתה עליה בסיבוכי ניתוח מיידים ולא נראתה תועלת משמעותית .במדדי השליטה על המחלה
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Oncology, General surgery, Medical licensing exam (IMLE), Diagnostic radiology.
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Sources
- NCCN Clinical Practice Guidelines in Oncology: Rectal Cancer, 2026 — Principles of radiation therapy and total neoadjuvant therapy
- ESMO Clinical Practice Guideline: Localised rectal cancer, 2017, updated 2024 — Diagnosis, treatment and follow-up
- Gunderson and Tepper's Clinical Radiation Oncology, 5th ed. (2021) — Rectal cancer
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.