Period and cohort trends in mortality from cancers of the uterus in England and Wales. A new theory of changing gene frequencies

Abstract

Analysis of the age distribution of cancers of the uterus reveals three clearly distinctive types: early- and late-onset cancers of the cervix and one form of cancer of the corpus. England and Wales mortality data are available for the three types combined from 1911; cancers of the cervix and corpus have been listed separately from 1951; In the highest age groups, 60–64yr and above, death rates fell fairly steadily from 1921–1925 to 1981–1982 whereas cigarette smoking — an alleged cause of cervical cancer — rose over much of that period. In the younger age groups, 55–59yr and below, the more complicated temporal trends include two marked cohort dips. The first dip affected cohorts born around 1911; this was followed by a rise up to the 1921 central cohort, then a steep fall to the 1936 central cohort and, finally, a further rise up to the 1946 cohort (at least). The period trends are probably caused by a decline in the impact of one or more precipitators of cervical cancer, such as the papilloma virus. Cohort shifts are attributed to autoaggressive attacks on parental germ cells, the zygote, or early-stage embryo that induce gene change to affect the frequency of women genetically predisposed to early-onset cervical cancer. Attacks are also triggered by one or more precipitating agents with a temporal, and possibly a seasonal, dependence. Implications of this hypothesis of cohort shifts are discussed.