What to Do When Surgical Resection Does Not Achieve Clear Margins in Localised Lower or Middle Third Rectal Cancer with Organ Preservation Intent

This protocol applies to patients with localised rectal cancer in the lower or middle third of the rectum, where the clinical goal is organ preservation and the tumour is mismatch repair proficient (microsatellite stable). It defines the management step indicated after the preceding surgical approach does not meet its primary oncological goal.

Clinical Scenario

Localised rectal cancer situated in the lower or middle third of the rectum, with organ preservation as the stated treatment intent and a mismatch repair proficient / microsatellite stable tumour profile. Multimodal treatment strategies for this population increasingly incorporate a watch-and-wait approach to pursue organ preservation.

Previous Line — Failure Condition

The preceding approach — surgical resection (including organ-preservation options such as local excision or salvage resection following watch-and-wait regrowth) — is considered insufficient when it does not achieve a microscopically complete R0 resection with a clear circumferential resection margin (tumour >1 mm from the CRM). Failure to reach this goal is the trigger for the next management step defined in this protocol.

Next Management Step — Overview

For eligible patients in this setting, an adjuvant combination chemotherapy approach may be considered on an individualised basis following prior radiotherapy or chemoradiotherapy.

Full eligibility criteria, regimen details, and clinical sequencing are available in the complete structured protocol.

Instant Access to Structured Evidence-Based Regimens

References

Management of localised rectal cancer located in the lower or middle third of the rectum when organ preservation is intended.
Multimodal treatment strategies for patients with rectal cancer are increasingly incorporating a watch-and-wait approach for organ preservation.
An adjuvant fluoropyrimidine-oxaliplatin combination can be offered on a case-by-case basis after RT or fluoropyrimidine-based CRT in patients achieving cCR with initial cN+ disease [I, B].

DOI: 10.1016/j.annonc.2025.05.528

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