residual mucosal lesions in patients with locally advanced rectal cancer after CRT are still confusing for decision to continue follow up or excise.

Investigators decided to compare two groups with cCR or nCR with MDT management decision to whether do ESD for this residual lesion or continue follow up and its effect on disease free survival.

Colorectal cancer (CRC) represents a significant health challenge in Egypt. According to GLOBOCAN 2020, rectal cancer ranks sixth in all cancers among males and females, with 5,231 new cases, accounting for 3.9% of all cancers. El-Moselhy et al., 2025 reported that the rectum was involved in up to 20% of CRC cases in Egypt .

In recent years, there was a shift in management of locally advanced rectal cancer (LARC) toward organ preserving strategies. After neoadjuvant chemoradiotherapy (CRT) or total neoadjuvant therapy (TNT), a notable proportion of patients achieve a clinical complete response (cCR) or near-complete response (nCR) making them candidates for either structured watch-and-wait (W&W) surveillance or selective local interventions designed to avoid total mesorectal excision (TME) .

In phase II OPRA trial, long-term organ preservation was achieved in approximately 50% of participants, with most tumor regrowth occurring within the first two years.

Despite that, small residual mucosal/submucosal lesions with cCR post CRT are still challenging in management with either W&W or ESD. Endoscopic submucosal dissection (ESD) offers en-bloc resection, comprehensive histopathologic evaluation (depth of invasion, lymphovascular invasion, budding, margins), and the option of salvage surgery if needed. Early evidence supports its feasibility and safety in this setting .

One meta-analysis confirms strong effectiveness and low rate of recurrence when ESD is used for residual or recurrent lesions with prior surgery or endoscopy.

Inclusion Criteria:

• Adult patients with rectal adenocarcinoma who underwent full course locoregional chemoradiotherapy with organ-preservation intent.

Post-CRT assessment showing either:

A. Small residual mucosal/submucosal lesion amenable to en-bloc ESD (CRT→ESD), OR B. Clinical/radiologic near-complete/complete response and decision to observe (CRT→Follow-up).

Exclusion Criteria:

• - Evidence of distant metastasis at post-CRT restaging.
• Lesions unsuitable for endoscopic resection (circumferential, deeply invasive on EUS/MRI).
• Patients who had immediate TME after CRT for other reasons.
• Unfit for endoscopy or follow-up.

Patients who completed locoregional chemoradiotherapy with organ preservation intent will be prospectively enrolled. Post-CRT restaging at 8-12 weeks will be discussed at MDT. Patients with a small residual mucosal/submucosal lesion amenable to en-bloc endoscopic resection will be offered ESD (CRT→ESD). Patients with clinical/radiologic complete or near-complete response and no endoscopically resectable residual lesion will be managed with structured surveillance (CRT→Follow-up)