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100

Pedunculated or sessile polyp (adenoma), GI did a colonoscopy, did peacemeal resection of the sessile peduncle, which showed invasive cancer with good histologic features; no nodes were examined. What would you do?

1) Be angry about why the patient is coming to you; It should be followed by surgery, GI. You don't do adjuvant chemo for T1.

2) piecemeal resection is in a way “fragmented specimen,” and you would do Pelvic MRI, CT C/A/P, Labs -CBC, CMP, CEA followed by consideration of colectomy with en bloc removal of regional Lymph nodes.

Answer -- 2

Fragmented specimen or margin cannot be assessed, or unfavorable histologic features need to be referred for surgical resection (segmental colectomy).

100

NICHE and NICHE 2 trial

NICHE Trial- Published: 2020 (Chalabi et al.)

  • Early-stage, non-metastatic colon cancer (T3–T4)

  • Included both dMMR and pMMR tumors.

Treatment:

  • Single dose ipilimumab (1 mg/kg) + two doses nivolumab (3 mg/kg)

  • Given pre-operatively (neoadjuvant)

  • Surgery followed ~4 weeks later

dMMR cohort

  • 100% pathologic response

  • 60% pathologic complete response (pCR)
    → exceptionally sensitive to immunotherapy

pMMR cohort

  • Very limited benefit

  • Major pathologic response in ~4%

Takeaway:
Proof-of-concept that short-course neoadjuvant immunotherapy is wildly effective in dMMR localized colon cancer.

✅ NICHE-2 Trial

Presented: ESMO 2022 (updated 2023)

Population:

  • Neoadjuvant treatment for locally advanced dMMR colon cancer

  • Much larger cohort than NICHE-1 (~112 patients)

Treatment:
Same short regimen:

  • Ipilimumab × 1 dose

  • Nivolumab × 2 doses

  • Surgery ~5 weeks later

Results:

  • 95% major pathologic response (MPR)

  • 67% pathologic complete response (pCR)

  • 0% recurrence at short-term follow-up

  • Treatment was well-tolerated; no surgical delays

Takeaway:
Confirms that brief neoadjuvant immunotherapy is highly effective and safe for dMMR colon cancer, potentially practice-changing.

✅ Clinical Implications (as of current practice)

  • For dMMR localized colon cancer, neoadjuvant immunotherapy is emerging as a new standard in trials.

  • pMMR tumors do not benefit—stick with standard surgery ± adjuvant chemo.

  • Still not routine outside trials, but rapidly evolving.