Inherited predisposition to breast cancer

Published on September 3, 2014   53 min

Other Talks in the Series: Molecular Genetics of Human Disease

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My name is Professor Diana Eccles and I'm a professor of cancer genetics at the University of Southampton and have a clinical practice in the Wessex Regional Genetic Service.
Breast cancer is very common worldwide, and the incidence varies quite markedly between countries. In Western Europe through to Asia, as you can see from the graphs here, mortality is less variable, and this depends a little bit on the different sorts of breast cancer that occur in these countries, but also of course on early diagnosis and treatment.
There are many risk factors that are known for breast cancer, and increasing age is a very typical risk factor for breast cancer and many cancers in the Western world. Late age at first birth is associated with an increased risk for breast cancer, with a threefold increase in risk for women having children after 30 years of age compared to women having children below 25 years of age. And of course, women are having fewer children in the Western world now. Excessive iradiation of the chest in the teenage years is known to be associated with an increased risk of breast cancer, and the evidence from the Hiroshima bomb also indicates that radiation exposure increases breast cancer risk. Replacement of oestrogen at the natural menopause also increases breast cancer risk, but particularly if it's given with progesterone. Oestrogen only seems not to increase the breast cancer risk significant. Obesity is clearly a risk for postmenopausal breast cancer but less so for premenopausal breast cancer. However, in all ages it increases the risk of dying from breast cancer. Early onset of periods and late menopause also increase the duration of exposure to the oestrogen, and both of those are risk factors that increase breast cancer incidence. And then the main breast cancer risk factor that we're concentrating on in this lecture, of course, is a family history of breast cancer. But independent of that, and also very heritable, is the mammographic density.