Effect of Tumor Treating Fields (TTFields, 150 KHz) Concomitant with Chemotherapy As First Line Treatment of Unresectable Gastroesophageal Junction or Gastric Adenocarcinoma

Patients receive continuous TTFields treatment using the NovoTTF-100L(P) device. TTFields treatment will consist of wearing four electrically insulated electrode arrays on the abdomen. The treatment enables the patient to maintain regular daily routine.

Oxaliplatin 130 mg/m\^2 intravenous infusion will be administered once every 3 weeks

Capecitabine 1000mg/m\^2 taken by mouth, twice daily on day 1-14, 3 weeks per cycle

Trastuzumab (HER-2 positive patients only) intravenous infusion will be administered once every 3 weeks on Day 1 of each cycle. First dose is 8mg/kg, followed by 6 mg/kg.