Medical Consortium for Screening Upper Gastrointestinal Cancers With Magnetically Controlled Capsule Gastroscopy

Inclusion Criteria: * asymptomatic subjects undergong magnetically controlled capsule gastroscopy for health checkup in medical consotium; * subjects able to give informed consent Exclusion Criteria: * suspected or known intestinal stenosis, obstruction, or fistula; * inoperability of refusal to accept any abdominal surgery; * dysphagia or gastric paralysis; * previous history of gastrointestinal disease; * with pacemaker, implanted-cardiac defibrillator or other implanted electromedical devices; * need for standard magnetic resonance imaging examination within seven days after swallowing the MCCG, unless the capsule is confirmed to have been excreted; * other factors that are not suitable for inclusion evaluated by medical stuff