Conversion surgery after successful response to chemotherapy (S-1 + oxaliplatin + nivolumab) in a patient with stage IV gastric cancer with peritoneal metastasis (P1, CY1): a case report

Takayuki Noma; Masaaki Nishi; Chie Takasu; Yuma Wada; Kozo Yoshikawa; Takuya Tokunaga; Toshihiro Nakao; Hideya Kashihara; Toshiaki Yoshimoto; Yuko Miyakami; Kengo Atsumi; Hisanori Uehara; Mitsuo Shimada

doi:10.1007/s13691-023-00628-4

Conversion surgery after successful response to chemotherapy (S-1 + oxaliplatin + nivolumab) in a patient with stage IV gastric cancer with peritoneal metastasis (P1, CY1): a case report

Int Cancer Conf J. 2023 Aug 12;13(1):11-16. doi: 10.1007/s13691-023-00628-4. eCollection 2024 Jan.

Affiliations

¹ Department of Surgery, Institute of Biomedical Sciences, Tokushima University Graduate School, 2-50-1 Kuramoto Town, Tokushima City, Tokushima 770-8503 Japan.
² Division of Pathology, Institute of Biomedical Sciences, Tokushima University Graduate School, 2-50-1 Kuramoto Town, Tokushima City, Tokushima 770-8503 Japan.

Abstract

We here present a case report of a patient with Stage IV gastric cancer with peritoneal metastasis (P1, CY1) who underwent conversion surgery after a successful response to chemotherapy (S-1 + oxaliplatin + nivolumab). The patient was a woman in her 60 s. Her chief complaint was epigastric pain. Upper gastrointestinal endoscopy showed Type 4 advanced carcinoma on the lesser curvature of the gastric body. Biopsy showed Group 5 (poorly differentiated adenocarcinoma) and HER2 was negative. Staging laparoscopy revealed seeding in the round ligament of the liver (P1) and adenocarcinoma cells in ascites (CY1). Ten courses of chemotherapy (S-1 + oxaliplatin + nivolumab) were administered, after which contrast-enhanced computed tomography showed that the primary tumor had shrunk and seeding was no longer detectable. Upper gastrointestinal endoscopy revealed scar-like changes. A second staging laparoscopy revealed that ascites cytology was negative and a biopsy of the round ligament of the liver showed no malignant cells (P0, CY0). Conversion surgery comprising laparoscopic total gastrectomy with D2 lymph node dissection and resection of the round ligament of the liver was performed. The postoperative course was uneventful. Histopathological examination of the resected specimen revealed no tumor cells in the gastric mesentery or the round ligament of the liver. The pathological diagnosis was gastric cancer [M, U, L, Less, Ant, Post, type4, T3(SS), N0, M0 (H0, P0, CY0), ypStage IIA]. Adjuvant chemotherapy (S-1) was commenced. The patient is still alive 7 months later with no evidence of recurrence.

Keywords: Advanced gastric cancer; Conversion surgery; Immune checkpoint inhibitor; Nivolumab; Oxaliplatin; S-1.

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