[Epidemiologic studies on multiple cancers in Japan].

During a 21-year period, 3040 patients with malignant tumors were treated at the Division of Surgery, Fukuyama National Hospital. Of these 86 (2.8%) were diagnosed as having double cancers. The simultaneous double cancer rate was 27.3%. Statistical study showed that the etiology had a relation to family history and previous therapy, but not to immunology. The prognosis was good and diagnosis by RI was non-specific.