From metastatic disease to no evidence of disease after conversion liver surgery in advanced gastric cancer with liver metastases: A case report.

Stage IV gastric cancer with liver metastases has a poor prognosis. Conversion surgery may enable long-term disease control in selected patients, but pathological complete response is rare and is usually defined only for surgically resected specimens. Here, a 54-year-old female with initially unresectable, HER2-negative, pMMR-by-IHC, EBER-positive gastric cancer and synchronous liver metastases received first-line XELOX plus tislelizumab for 4 cycles. Because of suspected oxaliplatin hypersensitivity, treatment was changed to cisplatin plus capecitabine plus tislelizumab for 3 cycles. After subsequent suspected platinum hypersensitivity, treatment was changed to capecitabine plus tislelizumab for 7 cycles. After 14 cycles, repeat endoscopic biopsy showed no tumor cells. Imaging showed significant regression of liver lesions. After multidisciplinary discussion, the patient underwent conversion liver surgery comprising resection of selected liver lesions and radiofrequency ablation of other liver lesions. R0 status was confirmed only for the resected liver specimens; ablated lesions had no pathological specimen. Histopathological examination of the resected liver specimens showed no residual viable tumor cells, consistent with pathological complete response in the resected liver lesions. The gastric primary was assessed as clinical complete response by endoscopy and biopsy. At last follow-up 1 month after surgery, imaging showed no evidence of disease; long-term outcome remains unknown. This case illustrates that selected patients with advanced gastric cancer and liver metastases may achieve a strong response to tislelizumab-based immunochemotherapy and liver-directed conversion treatment. However, the long-term benefit, the role of omitting gastrectomy, and the significance of FAPI/FDG discordance remain uncertain.