In two prospective studies, including a total of 1,353 and 1,914 male and female participants, a variety of medical and psychosocial risk factors were assessed by means of personal interviews and observational categories. The incidence of gastric cancer was determined for the following study groups: 1) all persons with chronic atrophic gastritis and pernicious anemia who had one to three relatives with a history of gastric cancer, 2) persons with a previous operation for gastric ulcer (partial resection) and one to three relatives with gastric cancer, and 3) a comparable group without any of these characteristics, serving as a reference. The hypothesis was that significantly more gastric cancer was to be expected in groups 1 and 2. A second hypothesis was that interaction between the specific precursors and psychosocial risk factors (chronic hopelessness due to withdrawing objects) was useful for the prediction of gastric cancer. The results may open new avenues for the prevention of gastric cancer via preventive psychotherapy in identified risk groups.