Analysis of hereditary component of cancer by use of a familial index by site

To quantify hereditary factors In the risk of cancer, we matched 1283047 ca ncer patients listed In the Swedish Cancer Registry with healthy controls f rom a national database, and Identified the number of Individuals who were first-degree relatives of other indivduals In the same cohort. Division of the number of relatives In the patient cohort by the number In the control cohort yielded a "familial index". The following cancers had high familial Indices: eye :16.5 (95% CI 2.5-666), testis 9.0 (3.2-35), Hodgkin's disease 6.5 (2.3-26.0), and thyroid 6.2 (3.7-12). Overall, however, familial facto rs made only a minor contribution to susceptibility to cancer.