Conversion surgery for gastric remnant cancer with liver metastasis after nivolumab combination chemotherapy achieving pathological complete response: a case report and literature review

Abstract

Background: Nivolumab combination chemotherapy has recently emerged as a potential first-line treatment for patients with unresectable or metastatic gastric cancer (GC). Further research has indicated that R0 resection by conversion surgery could be an effective treatment strategy to improve overall survival. However, there have been limited reports on the successful application of conversion surgery following combination chemotherapy achieving pathological complete response (pCR) in cases of advanced gastric remnant cancer with liver metastasis. Here, we present a case of long-term survival in a patient who underwent this treatment.

Case presentation: A 54-year-old man was initially referred to our department for treatment of stage III (cT3N1M0) gastric cancer where he underwent laparoscopic distal gastrectomy and D2 lymph node dissection. After a year of uneventful follow-up, the patient was diagnosed with a tumor in the gastric remnant combined with liver metastasis, resulting in a diagnosis of stage IV (cT3N0M1) gastric remnant cancer. Subsequently, the patient was treated with four cycles of TS-1, Oxaliplatin, and Nivolumab as the first-line regimen. Remarkably, both the remnant tumor and liver metastasis exhibited significant shrinkage, and no new lesions were found. Given this response, conversion surgery was performed to achieve complete resection of the remnant gastric cancer and liver metastasis, followed by laparoscopic remnant gastrectomy and partial hepatectomy. Pathological examination revealed the absence of residual carcinoma cells and lymph node metastases. Postoperatively, the patient was treated with adjuvant chemotherapy with S-1 for 1 year, and survived without recurrence for 18 months after conversion surgery.

Conclusions: Nivolumab combination chemotherapy shows promise as a clinically beneficial treatment approach for gastric remnant cancer with liver metastasis, particularly when pCR can be achieved following conversion surgery.

Keywords: First-line chemotherapy; Gastric cancer; Nivolumab combination chemotherapy; Pathological CR.

Fig. 1

A Results of upper gastrointestinal endoscopy 1 year after initial surgery. Upper gastrointestinal endoscopy showing a Type 2 tumor in the efferent side of the remaining stomach. B Pathological findings of remaining stomach. From the biopsy of the remaining stomach tissue obtained by upper gastrointestinal endoscopy, a poorly differentiated adenocarcinoma was found histologically, characterized by the formation of solid nests and lacking glandular structures. Some tumor infiltrating lymphocytes, as indicated by arrows, were observed

Fig. 2

Result of CT 1 year after initial surgery. A CT showing a 2.5 cm low-density area in segments 6 and 7 of the liver. B FDG–PET performed at the same time as CT showing abnormal uptake at the site of liver metastasis

Fig. 3

Result of upper gastrointestinal endoscopy after four courses of nivolumab combination therapy. Upper gastrointestinal endoscopy revealed a trend in tumor reduction in the gastric remnant

Fig. 4

Result of CT after 4 courses of nivolumab combination therapy. CT demonstrating a reduction in the size of the liver metastasis to approximately 1 cm

Fig. 5

Resected remnant GC and liver with metastasis. A Resected remnant GC. Tumor residue was observed macroscopically, raising suspicion of malignancy. B Resected liver metastasis. The presence of the tumor was not clearly evident macroscopically

Fig. 6

Pathological findings after conversion surgery. A, B Pathological finding of remnant GC. A is with low power field and B is with high power field. The lesion, macroscopically classified as type 3, as shown in Fig. 5A, was dissected for pathological examination. However, no poorly differentiated adenocarcinoma was found. Extensive fibrosis and scarring were observed in all sections, with no apparent malignant cells identified. Therefore, histological assessment of therapeutic effect was determined to be grade 3, indicating evidence of pCR. C, D Pathological findings of liver with metastasis. C is with low power field and D is with high power field. This demonstrates fibrous scar formation with moderate infiltration of lymphocytes and histiocytes, suggesting the disappearance of cancer cells due to preoperative treatment. No residual malignant cells were identified