Pilot Feasibility Study of Neoadjuvant Chemoradiotherapy with S-1 in Patients with Locally Advanced Gastric Cancer Featuring Adjacent Tissue Invasion or JGCA Bulky N2 Lymph Node Metastases

Abstract

To improve the prognosis of locally advanced gastric cancer, clinical trials of neoadjuvant chemotherapy (NAC) are being performed. Although neoadjuvant chemoradiotherapy (NACRT) generally achieves superior local tumor control to NAC, its efficacy for locally advanced gastric cancers remains unclear. Therefore, a prospective trial was conducted to explore the feasibility and safety of NACRT with oral S-1 in a series of cases. Patients who had Japanese Gastric Cancer Association (JGCA) cStage IIIB gastric cancer were enrolled onto this study and received oral S-1 (65 mg/m(2)/day) administration and 50-Gy radiotherapy followed by radical surgery. The primary end points were completion of therapy and safety. Between October 2005 and September 2008, 12 eligible patients were enrolled. Two could not complete the chemotherapy because of grade 3 toxicity. R0 resections were performed in 11 patients (91.7 %) (95 % confidence interval 61.5-99.8). Although operative morbidity was observed in two cases, there were no postoperative deaths. A pathologic response was observed in 10 patients (83.3 %). In five (62.5 %) of eight gastric cancers with invasion to adjacent structures, microscopic tumor deposits were not found in the affected organs. The 3-year survival rate was 58.3 % during a median follow-up period of 36 months. Although this study is preliminary, the present regimen seems to be feasible and safe as a treatment for locally advanced gastric cancers featuring adjacent tissue invasion or JGCA bulky N2 disease. This treatment approach should now be tested using the new tumor, node, metastasis staging system in a large clinical trial.