T3/T4 Rectal Cancer with Involved or Threatened CRM: Management After Total Neoadjuvant Therapy
This protocol applies to patients with locally advanced rectal cancer — clinically staged T3 (N any) with an involved or threatened circumferential resection margin (CRM) on MRI, T4 (N any), locally unresectable disease, or medically inoperable patients — who have completed total neoadjuvant therapy (TNT) and require a structured next-step management plan at restaging.
This population encompasses higher-risk presentations: T3 tumours where MRI confirms involvement or threat to the CRM (defined as within 1 mm of the mesorectal fascia; or, for lower-third rectal tumours, within 1 mm of the levator muscle; or, for anal canal lesions, invasion into or beyond the intersphincteric plane), as well as T4 disease, locally unresectable tumours, and patients who are medically inoperable. For all of these presentations, total neoadjuvant therapy (TNT) is the only recommended primary approach.
The preceding treatment — TNT combining radiotherapy and chemotherapy — aimed to achieve a complete clinical response with no evidence of residual disease on digital rectal examination, rectal MRI, and direct endoscopic evaluation, assessed at restaging approximately 8 weeks after completion of radiotherapy. When complete clinical response is not confirmed at restaging, the next step in management applies.
Following restaging, management centres on surgical resection including total mesorectal excision, with intraoperative radiation considered for select candidates. For patients in whom resection is contraindicated, a systemic approach for advanced disease is used. The complete algorithm, patient-selection criteria, and full range of options remain in the structured protocol.
References
- T3, N any with involved or threatened CRM (by MRI); T4, N any or Locally unresectable or medically inoperable.
- Involved CRM: within 1 mm of mesorectal fascia; or, for lower third rectal tumors, within 1 mm from levator muscle; or, for anal canal lesions, invasion into or beyond the intersphincteric plane.
- For patients with higher-risk stage II or III rectal cancer, including cT3 lesions with involved or threatened CRM by MRI, cT4 lesions, and locally unresectable or medically inoperable disease, TNT is the only recommended approach.
- Transabdominal resection.
- For select patients who may be candidates for intraoperative radiation therapy (IORT), see Principles of Radiation Therapy (REC-E*).
- When resection is contraindicated following primary treatment, patients should be treated with a systemic regimen for advanced disease.