[ CancerWeb Home
| Comments
| CancerWeb Report Index ]
The CancerWeb Report, What's New In Cancer
Cancer and oral contraceptives: September 1995
Last modified on:
Tuesday, April 20, 1999 12:03:10
Copyright © 1994-2008, Information Ventures, Inc.
Cancer and oral contraceptives - A report by Drs. dos Santos Silva and Swerdlow of the London
School Hygiene and Tropical Medicine in the August, 1995 issue of the British Journal of Cancer described trends in cancers of the breast, ovary, and endometrium in England and Wales in relation to fertility and oral contraceptive (OC) use. Between 1962 and
1987, there were increases in incidence of breast (0.95%/year) and ovarian (0.76%/year) cancers, but little change in endometrial cancer (0.13%/year). These increases were restricted to older age groups, masking significant declines in younger women. Mortality showed similar trends. Oral contraceptives were introduced in the UK in 1960, with cumulative ever users rising from 40% for women born in 1930s, to 70% for those born in the 1940s and 80-90% for those born in 1950s and 1960s. Only those born after the 1930s were exposed to OCs early in life; they showed the decrease in cancers. There was the expected
inverse relationship between fertility and breast cancer for women born before 1910, but it was opposite for subsequent birth cohorts: risks rose for those born 1910-1929 despite increased fertility, and then declined subsequently when fertility was falling. Nulliparity (having no children) halved between 1910 and 1935 while risks increased slightly, but nulliparity increased for the 1945-49 and 1955-59 groups, whereas breast cancer risks fell. As regards uterine cancer, women with two children are known from several studies to have an 80% reduction compared to those without. However, since the birth cohort of
the 1930s, risk for uterine cancer has continued dropping despite further reduction in parity, and the same goes for ovarian cancer. The conclusion: OCs protect against uterine and ovarian epithelial cancers, but the picture for breast cancer, although
apparently similar, is complicated by dietary fat and menarche age changes.
Copyright (c) 1994-2008, Information Ventures, Inc.
Mail us at: Customer-Service@infoventures.com
http://infoventures.com