Response-adapted Total Neoadjuvant Therapy Guided by Induction Chemotherapy in Early- and Intermediate-risk Low Rectal Cancer for Implementation of a Watch-and-wait Strategy

Summary

This study investigates the feasibility of an organ-preserving "watch-and-wait" strategy in patients with mid-to-low rectal cancer who achieve a good response after total neoadjuvant therapy (TNT). By retrospectively and prospectively analyzing patients who complete TNT following effective induction chemotherapy, the study aims to assess organ preservation rates and evaluate whether non-surgical management can provide comparable oncologic outcomes to radical surgery while improving functional recovery and quality of life.

Eligibility

Inclusion Criteria:

* Age: 18-80 years; no restriction on sex.
* Histologically confirmed rectal adenocarcinoma with immunohistochemistry and/or genetic testing showing pMMR/MSS status.
* Tumor characteristics assessed by chest-abdominal CT, rectal ultrasound, and MRI meeting all of the following criteria:

  1. The lower edge of the tumor is ≤5 cm from the anal verge as measured by digital rectal examination or MRI;
  2. Clinical stage cT1-3abN0-1M0 (for cT1N0, patients suitable for endoscopic resection are excluded);
  3. MRF (-) (\>1 mm), EMVI (±);
  4. Negative lateral lymph nodes and \<7 mm in size;
  5. Maximum tumor length ≤5 cm;
  6. Tumor circumference involvement ≤2/3.
* After receiving at least two cycles of induction chemotherapy with the XELOX regimen, MRI assessment shows treatment response (tumor length reduced by ≥30% compared with baseline).
* Completion of total neoadjuvant therapy (TNT), including long-course chemoradiotherapy and consolidation chemotherapy (radiotherapy: 25-28 fractions; chemotherapy: 6-8 cycles).
* (For the prospective cohort) Provision of written informed consent for participation in this observational study.

Exclusion Criteria:

* Patients with a history of, or concurrent, other malignant tumors (except for cured basal cell carcinoma of the skin or carcinoma in situ of the cervix);
* Patients with severely incomplete clinical data that preclude effective evaluation;
* (For the prospective cohort) Patients who refuse to provide written informed consent.

Conditions2

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