Breast cancer risk after radiation to the chest: early menopause and hormone replacement therapy

Early menopause decreases the risk of subsequent breast cancer even for women who are treated with hormone replacement therapy

Published: 03/06/2018


In the general population, exposure to female hormones has been shown to increase risk of breast cancer. Breast cancer risk is increased for women who have early puberty and those who have late menopause. Hormone replacement therapy after menopause has also been linked to increased breast cancer risk. However, the relationship between hormone exposure and breast cancer risk in women treated with chest radiation for childhood cancer is unclear.  LTFU Study researchers conducted a study to learn more about this important topic.

The research team looked at the experiences of 1,108 female LTFU Study participants who received chest radiation for childhood cancer diagnosed between 1970 and 1986.

One hundred ninety-five participants were diagnosed with breast cancer during the course of the study. Of these, 102 had tumors that "were estrogen-receptor positive." This means that the tumor grows in response to the female hormone estrogen. Estrogen is naturally produced in the body and is important for reproductive health.

The study showed that:

  • Women who received chest radiation within one year of the time they started having menstrual periods had a greater risk of developing breast cancer than those who had been menstruating for longer when they were treated.
  • Early menopause decreased breast cancer risk.
  • Women treated with both chest radiation and chemotherapy that impaired the function of their ovaries had a decreased breast cancer risk.
  • Survivors who entered menopause before age 20, including those who were treated with hormone replacement therapy, had a lower breast cancer risk than premenopausal survivors.

What does this mean for you?

Hormone replacement therapy in post-menopausal childhood cancer survivors slightly increased breast cancer risk but not to the same degree as the naturally produced hormones in survivors who had not gone through menopause.

This is a very important finding because hormone therapy can prevent or delay osteoporosis, improve sexual function, and have other positive benefits for quality of life of menopausal survivors.

This new information can help survivors who experienced early menopause weigh the potential risks and benefits of hormone replacement therapy. For some survivors the benefits may outweigh the relatively small increase in breast cancer risk.


Moskowitz CS, Chou JF, Sklar CA, et al. Radiation-associated breast cancer and gonadal hormone exposure: a report from the Childhood Cancer Survivor Study. Br J Cancer. 2017 Jul 11;117(2):290-299.