Does the Age that I First Got My Menstrual Period Affect My Risk for Breast Cancer?

— -- Question: Does the age that I first got my menstrual period and its pattern affect my risk for breast cancer?

Answer:One of the risk factors for breast cancer is the breast's exposure to your own hormones. That sounds like a tough situation because you can't do much about your own hormones, but in fact we believe that the more menstrual cycles or hormone cycles that the breast is exposed to, the greater the chance of developing a breast cancer.

Well, every time you go through a menstrual cycle, the breast gets ready for a potential pregnancy and so some of the cells that are designed to do this, start doubling -- we call that proliferation. They're building structures that may be needed if a pregnancy were to occur. Well that means that DNA has to be copied and copied correctly; every time the cell divides, you have to have an equal set of chromosomes in the new cells and so the DNA divides and gets copied and so on. The more times that happens, as you can imagine, the greater the chance that the DNA won't get copied accurately and so there's an increased risk of breast cancer the more hormone cycles the breast is exposed to.

So women who start getting their periods early in life and therefore have more hormone cycles are at a little bit of an increased risk, and women who continue to menstruate later on in life, again, having more hormone cycles are at a little bit increased risk. So there is some risk associated with having early periods.

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