Heredity of Cancer Elucidated by a Study of Unselected Twins

Abstract

In an unselected sample of 6,893 Danish twin pairs, a total of 1,038 cases of cancer were found. In the group of identical twins (1,528), 143 cancer probands had unaffected partners, 8 had partners with cancer of the same site, and 13 had partners with cancer of other localizations. In the same-sexed fraternal twins (2,609), the corresponding numbers were 292, 9, and 39. Thus the concordance rates in the two groups do not differ significantly, indicating that gene differences can only to a limited extent explain the diversity in the population with regard to the occurrence of malignant growth.