65 Background: Combination chemotherapy involving S-1 and irinotecan (IRI-S) has failed to demonstrate a survival benefit over S-1 alone in metastatic gastric cancer. However, the tumor response rate was significantly higher with I-RIS. Therefore, we evaluated the effect of I-RIS as neoadjuvant chemotherapy for locally advanced gastric cancer. Methods: Patients with locally advanced gastric adenocarcinoma, T3-4, N0-3, M0, for whom curative surgery was planned after neoadjuvant chemotherapy, PS 0-1, with adequate organ function were enrolled in this study. Patients received irinotecan 80 mg/m2 on days 1 and 15 and oral S-1 80 mg/m2/day on days 1 to 21. Treatment was repeated every 28 days for 2 courses. Patients then underwent gastrectomy with lymphadenectomy. After surgery, patients resumed treatment with S-1 alone for 1 year. Results: Of the 39 patients enrolled, 37 were eligible. Two cycles of chemotherapy were completed in 34 patients, and surgery was performed in 33 patients. Of 27 RECIST-evaluable patients, 16 (59%) had a partial response and 9 (33%) had stable disease. Major grade 3 toxicities were neutropenia in 6, anorexia in 4, nausea in 3, diarrhea in 2, and fatigue in 2. Resection was performed in 32 (86%) patients and R0 resection was possible in 20 (54%) patients. The reason for R1/R2 were cy+ in 6, M1(LYM) in 5, M1(PER) in 4, M1(HEP) in 1 and PM+ in 2. Postoperative complications were observed in 13 (39%) patients. There were no treatment-related deaths. Pathological response was observed in 13 of 32 patients (41%); 2 patients had pathological CR. Median survival time was 15.9M and median progression-free survival (PFS) was 5.9M. Overall survival and PFS were significantly better in patients underwent R0 resection (p < 0.0001). Neither objective tumor response nor pathologic response predicted the survival. Conclusions: These results show that neoadjuvant S-1 and irinotecan combination chemotherapy was active and feasible for treating locally advanced gastric cancer. R0 resection is essential to achieve long-term survival. Therefore, careful diagnosis with staging laparoscopy before surgery is mandatory to avoid non-curative operation. Clinical trial information: NCT00134095.
Development and Validation of a Computed Tomography–Based Radiomics Signature to Predict Response to Neoadjuvant Chemotherapy for Locally Advanced Gastric Cancer