Inclusion Criteria:

- Adult patients, 18 to 75 years of age

- Curatively resected HER2-positive gastric or gastro-esophageal junction
adenocarcinoma; HER2+ status as defined by IHC2+ or IHC3+ with corroborative FISH+
result

- Patients with Stage IB (T1N1M0) disease or higher, except metastatic (Stage IV)
disease

- Eastern Cooperative Oncology Group (ECOG) performance status
- Left ventricular ejection fraction >/= 50%

- No known contraindication to capecitabine, oxaliplatin or trastuzumab

- No contraindication for radiotherapy or has not received any previous radiotherapy
for any reason

Exclusion Criteria:

- Previous neoadjuvant chemotherapy and/or radiotherapy

- Any disruption in the physical integrity of the upper gastrointestinal tract (except
surgical intervention for gastric or gastro-esophageal junction carcinoma)

- Known (previously diagnosed and on-going) malabsorption syndrome

- Active gastrointestinal bleeding

- Any other malignancies within the past 5 years, except for squamous cell carcinoma of
the skin

- Clinically significant cardiac or cardiovascular disease

- Uncontrolled hypertension

- Patients who have received any investigational anti-cancer treatment or are being
treated in a concomitant investigational drug study