A Phase II Trial of Postoperative Radiation Therapy of Gastric Cancer Patients Basing on a New Method of Lymph Node Target Volume Delineation: The Study Protocol, Toxicity and Efficacy

Purpose/Objective(s): To prospectively investigate the safety and efficacy of neoadjuvant radiation therapy with concurrent weekly oxaliplatin plus TS-1 (nSOXRT) or TS-1 alone (nSRT) followed by D2 resection for locally advanced gastric cancer. Materials/Methods: The patients with stage IIB-IIIC gastric cancer who received chemoradiation therapy (CRT) and surgery in Peking University Cancer Hospital from March 2009 to October 2014 were enrolled. They were treated with neoadjuvant intensity-modulated radiation therapy (IMRT), given to 45 Gy to clinical targeting volume (CTV) and a concomitant boost to 50Gy to gross targeting volume (GTV) in 25 fractions, 5 fractions per week. Concurrent chemotherapy regimens included oral TS-1 (60 mg/m/day in twice daily) plus oxaliplatin 40 mg/m intravenously weekly or TS-1 alone (120mg/day in twice daily). Surgery was performed within 6-8 weeks after the last irradiation. Results: Thirty-five patients were studied according to the inclusive criteria. The median age was 61 years (range 33-73), and all were male. Clinical staging were as follows: 3 cT3, 32 cT4; 1 cN1, 24 cN2, 10 cN3. Twenty-five and ten patients received nSOXRT and nSRT, respectively. All patients completed radiation therapy. Five patients cannot tolerate concurrent chemotherapy due to toxicity, with a completion rate of 85.7%. There was no grade 4 toxicity. The incidence of grade 3 toxicity was 11.4%, including: thrombocytopenia (5.7%), neutropenia (2.9%) and radiation esophagitis (2.9%). The overall response rate (CR+PR) was 62.9%(22/35). None of these patients withdrew from surgery due to toxicity; two patients did not undergo resection due to distant metastases and five due to peritoneal metastases observed in time of laparoscopic approach. Twenty-eight patients (80%) underwent radical D2 resection. Pathological complete response occurred in 8.6% (3/35) of patients. The T and N downstaging rate were 92.9% (27/28) and 89.2% (25/28), respectively. Surgery-related complications consisted of anastomotic leakage in 2 (7.1%), infection in 3 (10.7%) and hemorrhage in 2 (7.1%) patients. The perioperative mortality was nil. The median survival time was 29.6 months (95% confidence interval, 19.7-39.5 months). The 1year and 2-year overall survival (OS) rates were 89.2% and 56.8% respectively. Conclusion: The present schedule of multimodality treatment for locally advantage gastric cancer showed an acceptable toxicity, promising efficacy and safety for D2 resection. Author Disclosure: Y. Li: None. Z. Li: None. X. Li: None. J. Ji: None. Y. Cai: None.