Hirofumi Kishimoto

Histological complete response in advanced gastric cancer after 2 weeks of S-1 administration as neoadjuvant chemotherapy

Single-agent or combined chemotherapy with the novel oral fluoropyrimidine anticancer drug, S-1 (TS-1), has been reported to be useful for the treatment of advanced gastric cancer. Here, we report a patient with advanced gastric cancer achieving a complete response (CR) after 2 weeks of administration of S-1 as neoadjuvant chemotherapy. A 78-year-old woman with epigastric pain was diagnosed as having advanced gastric cancer. S-1 was administered orally, at a dose of 50 mg twice a day every day for 2 weeks, followed by a 2-week drug-free period. No obvious adverse reactions occurred. Subsequently, the patient underwent distal partial gastrectomy with D2 lymph node dissection. Pathological examination indicated no remnant signet-ring cells in the excised specimen, no lymph node metastasis, and unnatural fibrosis in one of the No. 3 lymph nodes. The neoadjuvant chemotherapy induced a CR according to the Japanese classification of gastric carcinoma.

Multiple gastrointestinal stromal tumors with novel germline c-kit gene mutation, K642T, at exon 13

Multiple gastrointestinal stromal tumors (GISTs) caused by germline c-kit gene mutations are an extremely rare autosomal dominant disorder. A 57-year-old Japanese woman was referred to a hospital for appetite loss and severe weight loss. She had 2 large abdominal masses around the stomach, which were surgically resected. Histological examination revealed that these tumors were GISTs. Multiple microscopic GISTs and diffuse hyperplasia of the interstitial cells of Cajal were also seen in the background gastric and small intestinal walls. Characteristically, the GISTs showed severe hyalinization with calcification and partial heterotopic ossification, which may have caused the patients severe dysphagia. Mutational analysis of the c-kit gene revealed a substitution at codon 642 in exon 13 (K642T) in the tumor, normal ileal mucosa and peripheral blood leukocytes, indicating that the mutation is in the germline. This is the first case of multiple GISTs with novel germline c-kit gene mutation at exon 13.

The surgical and oncological outcomes of conversion surgery for patients with initially unresectable gastric cancer

Background: Conversion therapy is a surgical option for unresectable gastric cancer in cases wherein non-curative factors are initially managed by induction chemotherapy. However, the indications for resection remain unclear. Thus, this study aimed to assess the feasibility and efficacy of conversion therapy, based on the data from our facility. Methods: Patients (n=97) with unresectable gastric cancer received chemotherapy in our facility between January 2010 and August 2016. Surgical resection was performed in 16 of them after chemotherapy had rendered the tumor resectable. We retrospectively examined clinicopathological variables and oncologic outcomes in these 16 cases. Results: Of the 16 patients who underwent resection, R0 resection was possible in 15 patients, whereas R1 resection was performed in the remaining 1 patient. Postoperative complications arose in 6 patients (37.5%) but with no mortality. The median overall survival (OS) in the conversion therapy patients (n=16) was 50 months. Among the patients who underwent conversion therapy, univariate analysis showed that the patients with type 4 gastric cancer had a poor prognosis (P=0.0009). Conclusion: The conversion therapy may improve OS in only some of the patients who responded to induction chemotherapy, our results suggest that conversion therapy does not improve the outcomes in patients with type 4 gastric cancer.