A cohort study of twins and cancer.

Given the current explosion of knowledge of the genetics and molecular biology of cancer, the possibility of widespread testing for inherited predisposition to cancer has been raised. The main objective of this study was to assess the effect of inherited predisposition on cancer mortality among the National Academy of Sciences-National Research Council Twin Registry. The twins were white male United States veterans of World War II, who were born during the period 1917-1927. The follow-up period was from 1946 to 1990, and some cause of death was determined with the use of death certificates. We compared concordance for death from cancer among 5690 monozygotic twin pairs to that among 7248 dizygotic pairs. A possible effect of inherited predisposition to death from cancer was considered present if concordance for cancer mortality among monozygotic twin pairs was greater than it was among dizygotic twin pairs. Among monozygotic and dizygotic twins, a total of 1918 cancer deaths was observed. Concordance for death from cancer at all sites among monozygotic twins was higher than it was among dizygotic twins (overall rate ratio, 1.4; 95% confidence interval, 1.0-2.0). For each zygosity group, two or fewer pairs were observed to be concordant for death from cancer of a specific site, with the exception of lung cancer.(ABSTRACT TRUNCATED AT 250 WORDS)