Carcinoma of the Breast in Homologous Twins

Abstract

The role of heredity in disease has interested observers since early times. The recurrence of such diseases as hemophilia and peroneal atrophy in male members of certain families illustrates well the sex-linked hereditary character of these diseases. Likewise the direct inheritance of Huntington9s chorea seems well established. The part played by heredity in tumors has been less easy to trace, however. It is generally agreed that certain types of cancer can be hereditary in mice. Maud Slye (1) says: “That the occurrence of cancer has its basis in inherited susceptibility seems now to be satisfactorily established by the results obtained in many controlled breeding experiments.” Proof of the hereditary nature of the disease in man is less satisfactory. Macklin (2) gives a number of reasons why it is so difficult for observers to agree on this point. She reaches the conclusion that no matter what the mechanism of inheritance is, whether the tumor tendency is inherited as a single characteristic or whether it comes about by the influence of many factors, it is dependent on heredity. Among the arguments assumed to be in favor of the hereditary nature of tumors is the occurrence of similar tumors in similar positions in homologous twins. It is with this argument in mind that the following cases are reported.