Endoscopic resection as a “resect-to-confirm” strategy after neoadjuvant downstaging for remnant gastric cancer

For locally advanced gastric remnant cancer (GRC), radical resection surgery remains the first-line clinical treatment ¹ but causes permanent organ loss and functional decline ² . Recent advances in neoadjuvant therapy (NAT), particularly targeted therapy (anti-CLDN18.2), have markedly elevated pathological complete response rates ³ , enabling exploration of organ-preserving strategies. We report a case of GRC treated with endoscopic local non-full-thickness resection (E-LNFR) after achieving the clinical complete response (cCR) following NAT.

A 69-year-old man with prior subtotal gastrectomy (24 years ago for duodenal ulcer) presented with an ulcerative lesion on the gastric remnant anastomosis ( Fig. 1 a ). Biopsy revealed moderately differentiated adenocarcinoma with high CLDN18.2 expression, HER2(–) ( Fig. 1 b, c ). Computed tomography (CT)/positron emission tomography-CT showed stage cT2N0M0 ( Fig. 1 d ). The patient declined radical total gastrectomy. After multidisciplinary discussion (MDT), a 3-week NAT regimen was formulated: oxaliplatin (130 mg/m ² , d1) + capecitabine (1,000 mg/m ² , bid, d1–14) + zolbetuximab (800 mg/m ² , d1). The patient completed two cycles but stopped due to grade 3 vomiting (CTCAE v5.0). Follow-up gastroscopy and radiology confirmed tumor regression, supporting the cCR ( Fig. 1 e–h ).

Fig. 1.

Pre‑therapeutic and post‑neoadjuvant diagnostic evaluations. a Anastomotic ulceration under white-light endoscopy (pre‑neoadjuvant; the black arrow indicates the lesion). b Pre‑treatment biopsy histopathology showing moderately differentiated adenocarcinoma (×100). c Immunohistochemistry demonstrating high Claudin 18.2 expression. d CT findings of the lesion prior to neoadjuvant therapy (the white asterisk indicates the lesion). e Anastomotic erosion under white light gastroscopy after neoadjuvant therapy (the black arrow indicates the lesion). f Magnifying gastroscopy revealed atypical tumor vessels after neoadjuvant therapy. g Post-treatment biopsy demonstrating inflammation without neoplasia (×100). h CT presentation of the lesion post-neoadjuvant therapy (the white asterisk indicates the lesion). CT, computed tomography.

To clarify pathological response and achieve curative treatment simultaneously, the MDT decided on E-LNFR ( Video 1 ). First, indigo carmine was sprayed to delineate lesion margins and argon plasma coagulation for boundary marking ( Fig. 2 a ). After submucosal injection, mucosal incision and dissection were done on the anastomosis’s oral side ( Fig. 2 b ). Dental floss-clip traction was used to expose the anastomotic lesion ( Fig. 2 c ). En bloc resection along the anastomosis was completed ( Fig. 2 d ). The specimen size was 4.5 × 3.8 cm ( Fig. 2 e ). Pathology revealed TRG 0 with negative margins ( Fig. 2 f ), confirming the pathological complete response. Postoperative recovery was uneventful.

Fig. 2.

The surgical procedure of E-LNFR. a Determination of the resection margin and marking of the lesion under endoscopy. b Incision of the mucosal layer and dissection of the submucosal layer. c Assistance with dental floss-tissue clip traction to facilitate resection of the anastomotic lesion. d Post‑resection wound bed after complete lesion removal. e A gross photograph of the resected specimen. f Postoperative pathology indicating low-grade dysplasia (×100). E-LNFR, endoscopic local non-full-thickness resection.

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E-LNFR for gastric remnant cancer. E-LNFR, endoscopic local non-full-thickness resection.

Video 1

This case introduces the “resect-to-confirm” strategy – an organ-preserving approach combining pathological verification with curative local resection for NAT-responsive gastric cancer. Prospective studies with a long-term oncologic follow-up are urgently needed.

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