Conversion surgery after S-1 plus oxaliplatin combination chemotherapy for advanced gastric cancer with multiple liver metastases.

Conversion therapy for gastric cancer is a new therapeutic concept. We report a case of a patient with advanced gastric cancer who underwent conversion surgery due to a remarkable regression of multiple liver metastases following chemotherapy. A 71-year-old man was referred to our hospital with gastric cancer. Esophagogastroduodenoscopy (EGD) revealed an irregular, nodular, ulcerated lesion in the lower third of the stomach. Analysis of biopsy specimens revealed a poorly differentiated adenocarcinoma. Abdominal contrast-enhanced computed tomography (CT) showed multiple liver mass lesions. The patient was clinically diagnosed with advanced gastric cancer with liver metastases and received S-1 plus oxaliplatin chemotherapy. After 6 cycles of chemotherapy, CT and magnetic resonance imaging showed complete resolution of the liver metastases, and EGD detected mucosal irregularities only. Since there was no evidence of further metastatic lesions in other organs, the patient underwent distal gastrectomy with D2 lymphadenectomy. The gross appearance of the surgically resected specimen showed a slightly elevated tumor measuring 4.5 × 3.5 cm. Pathological examination confirmed the diagnosis of a moderately differentiated gastric adenocarcinoma invading the muscularis propria with no lymph node metastases. The postoperative course was uneventful. The patient has continued to receive S-1 and oxaliplatin chemotherapy, and there has been no evidence of recurrence for 3 months following the operation. We propose that conversion therapy might be an effective treatment for patients with advanced gastric cancer; however, further studies and assessments are needed to confirm and establish this treatment strategy.