CONTRIBUTION OF FAMILIAL FACTORS TO THE OCCURRENCE OF CANCER BEFORE OLD-AGE IN TWIN VETERANS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 34  (4) , 658-671
Abstract
Familial factors were evaluated in deaths from all causes before age 62 among the 31,848 white male twin veterans who were followed during 1946-1978 through the National Academy of Sciences-National Research Council Twin Registry. Data is reported for this group on twin concordances and heritabilities of cancer recorded on the death certificate as an underlying or associated cause. The study subjects have a mortality from cancer 0.88 times, and one from all causes 0.84 times, that of USA white males, but this is very similar to the mortality of other USA veterans. Among 11,350 monozygotic (MZ) and 14,450 dizygotic (DZ) individuals in twin pairs alive on Jan. 1, 1946, 1162 MZ and 1646 DZ individuals died before Jan. 1, 1979. Cancer was diagnosed for 223 MZ and 323 DZ twins as an underlying or associated cause of death. Among the latter were 176 MZ and 274 DZ pairs with the only death in the pair a cancer death, 10 MZ and 8 DZ pairs concordant for cancer, and 12 MZ and 14 DZ pairs in which the 1st death in the pair from cancer was followed by death of the other twin from another cause. When account is taken of the 3 MZ and 2 DZ pairs concordant for lung cancer, most likely related to cigarette smoking, the twin cancer death concordance rates are very low, and they are not appreciably different between the 2 zygosity groups. Genetic factors may be important in some specific forms of cancer. However, genetic factors and early familial environment, generally shared by twin-pair members, apparently do not contribute much to mortality from most cancers between 30 and 60 yr of age.