[Breast cancer associated with other organ cancer reviewed from cancer family history].

Double cancers and related family histories were studied in eight patients who had developed cancers in the breasts and other organs. The incidence of double cancer among patients with breast cancer was 1.7% (8/472), and the age at first onset averaged 48. The organs involved were mainly the digestive system, thyroid and female sexual organs. The incidence of cancer was higher in the pedigree of double breast cancer patients than in those with solitary cancer. In follow-up study, it is necessary to elucidate the difference in characteristics between double and solitary breast cancer.