Complete response and long‑term survival after stereotactic body radiotherapy in a patient with liver metastasis from α‑fetoprotein‑producing gastric cancer: A case report

α-Fetoprotein (AFP)-producing gastric carcinoma (GC) (AFPGC) is a special subtype of GC that is clinically characterized by a high incidence of liver metastasis and poor prognosis. The present study reported the case of a patient with AFPGC who showed complete response (CR) after stereotactic body radiotherapy (SBRT) for liver metastasis. A 76-year-old male patient underwent total gastrectomy with D2 lymph node dissection for GC. The excised tumor was diagnosed as AFPGC due to the patient's high serum AFP level (3,763 ng/ml) and AFP expression on immunohistochemistry. The patient was diagnosed with liver metastasis two months after the surgery. F-fluorodeoxyglucose positron emission tomography indicated that the metastasis was a single recurrent focus. Although the patient underwent seven cycles of chemotherapy with S-1-based regimens, the metastatic tumor showed only a minor response despite the decrease in serum AFP levels. To realize high-quality disease control, SBRT was performed on the liver tumor (total dose of 48 Gy in four fractions). The metastasis showed a significant response two weeks after the completion of SBRT and CR two years later. CR was sustained and the patient survived with no evidence of recurrence 62 months after the diagnosis of liver metastasis. Literature data on the efficacy of radiotherapy for liver metastasis from AFPGC remain scarce. The present case report suggests that SBRT has high efficacy for oligometastatic diseases and may be included as an indication for the treatment of liver metastasis from AFPGC.