Estrogen and Breast Cancer Risk: Separating Fact from Fiction

James A. Simon, MD, reproductive endocrinologist, menopausal medicine specialist and Clinical Professor at George Washington University in Washington, DC, has been treating women for gynecologic issues and seeks to re-educate women and the medical community about the importance of and safety of menopausal hormone therapy.

Dr. Simon wants to debunk the long-held belief that hormone therapy for women in the early menopausal years leads to breast cancer. It is not that simple. Women’s health status, breast cancer status, lifestyle, age and other factors contribute to the risk of cancer, including breast cancer. Estrogen, once lauded as providing great relief to women experiencing hot flashes and night sweats, became vilified when The Women’s Health Initiative hormone study appeared to demonstrate a cause and effect between menopausal use of hormone and the risk of breast cancer. About 8-10% of women are walking around with breast cancer and don’t know it. Either they haven’t had a mammogram or the cancer is still too small to be detected. According to Dr. Simon, when women who have undiagnosed breast cancer go on hormone therapy, and it shows up in the follow-up mammogram, some will attribute the cancer to the hormone therapy. But did the hormone therapy cause the cancer?

Estrogen alone may actually have a protective benefit from breast cancer while helping with all the uncomfortable symptoms of menopause, and yet estrogen plus synthetic forms of progesterone, like those used in the Women’s Health Initiative, may increase the apparent risk of breast cancer, but the drugs themselves are not carcinogenic.

Estrogen versus Estrogen Plus Progesterone
Joann Manson, MD, professor of Medicine, Harvard Medical School, Brigham and Women’s Hospital, and Past President of the North America Menopause Society, echoes Dr. Simon’s point about the efficacy and safety of estrogen alone. Dr. Manson has worked for more than 20 years in the field of menopause. In a video on MyMenopause.com Dr. Manson who was involved in the Women’s Health Initiative (WHI) study offers key learning points from the WHI study:

  • Estrogen, given alone, without a progestogen to women who have undergone hysterectomy, had no increase in the risk of breast cancer.
  • In women who had an intact uterus and needed a progestogen to protect the uterine lining, who also took estrogen, were at higher risk for breast cancer. However, cancer was not detected until around year 4 or 5, so doctors do not recommend taking the combined medication for a prolonged period.

“I think it’s important to understand that all medications do have risks. It really comes down to the balance of benefits versus risk,” said Dr. Manson. “In a woman in early menopause who is having moderate to severe symptoms—hot flashes, night sweats, really worsening her quality of life, really interrupting her sleep and interfering with her daily activities, in most cases the benefits of hormone therapy outweigh the risk,” she adds.

Estrogen Timing Matters: The Estrogen Window
Dr. Simon recently spoke about this issue at the 2016 Annual Meeting of The American Congress of Obstetricians and Gynecologists (ACOG) and also in a video with Dr. Mache Seibel, a gynecologic expert and Editor of MyMenopause.com.

“Early use of hormone therapy…and by early I mean 50’s, is of overall benefit to women’s health in a variety of ways…If they are outside of the window, or late, they get mostly risk for being on estrogen only or hormone therapy,” says Dr. Simon.

So women should take hormone therapy early, during their late 40’s, or as close to menopause as possible, to benefit the most and experience fewer risks.

Women with BRCA Mutations
A portion of the women going through menopause carry BRCA gene mutations, which already puts them at an increased risk for breast and ovarian cancer. Susan Domchek, MD, of the University of Pennsylvania spoke at the 2015 North America Menopause Society Annual Meeting regarding this issue. Dr. Domchek’s recommendation is for women who have had their ovaries or ovaries and fallopian tubes removed to offset the risk of ovarian cancer, to add estrogen therapy in order to mitigate the risk of breast cancer.

“It’s important to know that women know that this is an option for them and they need to talk to their doctor about it,” Dr. Domchek.

Who May Have BRCA 1 or BRCA 2 Mutations?

  • Women with family members (sister, mother, aunt, or even father) who had early onset breast cancer (before the age of 40)
  • Women with family members who have had ovarian cancer
  • Women of Ashkenazi Jewish descent whose family members have had early onset breast, ovarian or pancreatic cancer.

SIDEBAR
Hormone Therapy and Breast Cancer Risk

  • Combination (estrogen and synthetic progestogen) hormone therapy increases breast cancer risk by about 26%. This sounds like a tremendous increase, but it represents the difference between 3.3 cases of breast cancer/1000 women increased to 4.1 cases of breast cancer/1000 for each year of hormone therapy…less than one women/year/1000.
  • Estrogen-only hormone therapy increases the risk of breast cancer, but only when used for more than 10 years. In the Women’s Health Initiative, estrogen-only hormone therapy reduced the risk of breast cancer by a similar amount (23%).
  • Whether an increase or a decrease, the size of these changes are considered to be rare. (=1/10,000 and < 1/1,000; =0.01% to < 0.1%; between 0.1 and 0.9/1000).

Contributed by

James A. Simon

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