Radiation therapy plus concurrent chemotherapy has been demonstrated a significant improvement in overall and disease-free survival according to Intergroup Trial 0116 in patients with gastric cancer after surgical complete resection. Advantage of application of IMRT has been shown in planning comparison studies for postoperative gastric patients. So the investigators designed the trial to see safety and efficacy of postoperative concurrent chemoradiotherapy of capecitabine combined with IMRT for stage II/II gastric cancer.

In Intergroup 0116, only 64% patients in concurrent chemoradiation group completed treatment as planed, but in recently reported ARTIST trial, capecitabine was admitted to concurrent with radiotherapy,patients who completed treatment as planed in concurrent group reach high as 80%. IMRT is an advanced radiotherapy technology which allows high conformal dose distribution to Planing Tumor Volume (PTV) and low dose to organ at risk. The purpose of this study is to evaluate feasibility and efficacy of concurrent IMRT combined with capecitabine for the treatment of gastric cancer patients after D1/2 surgery.

Inclusion Criteria:

1. Postoperative histologically confirmed advanced adenocarcinoma of the stomach or the gastroesophageal junction.

2. Age of 18 to 75, Karnofsky score higher than 70.

3. Postoperative histologically conformed metastasis in perigastric lymph nodes and/or tumor invasion to muscularis propria or subserosa, without positive incisal margin. Stage II/III(AJCC 7th).

4. No severe functional damage of major organ, normal blood cell, normal liver and kidney function.

5. No clinical findings of distant metastasis.

6. Predictive survival time longer than 6 months.

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Exclusion Criteria:

1. Peritoneal carcinomatosis, as diagnosed by mandatory laparoscopy or distant metastasis
2. Concurrent treatment with other experimental drugs or other anti-cancer therapy, or treatment within a clinical trial within 30 days prior to trial entry
3. Severe or uncontrolled cardiovascular disease (congestive heart failure NYHA III or IV, no myocardial infarction within the last 12 months, unstable angina pectoris, or significant arrhythmia)
4. Active or uncontrolled infection.
5. Definitive contraindications for the use of corticosteroids as premedication
6. Prior systemic (chemo- or targeted) treatment. Prior radiotherapy to the upper abdomen
7. Any contraindication to treatment with cetuximab, capecitabine or cisplatin
8. Previous malignancy within 5 years, with the exception of adequately treated cervical carcinoma in situ or localized non-melanoma skin cancer
9. Known hypersensitivity against any of the study drugs ( capecitabine)