Conversion Surgery for Alpha-Fetoprotein-Producing Esophagogastric Junction Cancer with Multiple Liver Metastases and Portal Vein Tumor Thrombus after Nivolumab Combination Chemotherapy: A Case Report and Literature Review. - Akai M; Takagi S; Toji T; Mitani Y; Shimabara M; Nobunaga Y; Matsumura T; Inoue M (Surgical case reports, 2026)