Early menarche: A risk factor for cancer?

Yes. Early onset of menstruation (menarche) — before age 12 — is a risk factor for certain types of cancers in women. These include:

• Breast cancer. Early menarche is associated with an increased risk of breast cancer.
• Endometrial cancer. Early menarche may be associated with endometrial cancer. However, this hasn't been proved.
• Ovarian cancer. The more ovulation cycles a woman has in her lifetime, the more likely she is to develop ovarian cancer. So early menarche can be associated with increased risk of ovarian cancer. On the other hand, multiple pregnancies, early-onset menopause and the use birth control pills — which stop ovulation but not menstruation — decrease the risk of ovarian cancer.

However, it's important to note that the effect of early menarche on cancer risk is very small. Discuss your cancer risks with your doctor so that appropriate screening tests can be done.