Danielle Shapiro, MD, MPH, Cancer Prevention and Treatment Fund
Breast cancer is the most common type of cancer in women around the world, and the second leading cause of cancer deaths among U.S. women.
Women who are diagnosed with early-stage breast cancer almost always undergo surgery to remove the cancer (either lumpectomy/partial mastectomy or mastectomy). Most will also choose at least one other treatment in addition to surgery.
If their cancer is estrogen receptor positive (about 84% of breast cancers), many women will try to take hormonal therapy for at least five years after surgery to lower the chances of cancer coming back in the future.
For pre-menopausal women younger than 35-40 years old who have estrogen receptor-positive cancer, ovarian suppression therapy may be considered. Ovarian suppression can be permanent (surgery) or temporary (medication), and it stops the body from making hormones.
Suppression therapy is sometimes recommended for women with stage 1 or 2 breast cancer who have high chance of the cancer returning, but more often recommended in women with stage 2 or 3 breast cancer who would ordinarily need chemotherapy. Suppression therapy is given in addition to tamoxifen or an aromatase inhibitor, and instead of or after chemotherapy.
How Does Ovarian Suppression Therapy Work?
Ovarian suppression stops the ovaries from making hormones, which stops women from having menstrual cycles. It should only be used in women who are pre-menopausal and at high risk for cancer recurrence.
There are 3 types of ovarian suppression: 1) monthly hormone injections (temporary), 2) surgery to remove the ovaries (which results in irreversible menopause), and 3) radiation ablation therapy to remove the ovaries.
How Effective is Ovarian Suppression Therapy?
A 2016 study found that 13% of women receiving both tamoxifen and ovarian suppression therapy died within 5 years of breast cancer compared to 15% receiving tamoxifen therapy only. This is a very small difference, but was statistically significant, which means that it did not just happen by chance. For women who also received chemotherapy, 23% of patients receiving tamoxifen only died within 5 years, compared to 19% of women receiving tamoxifen plus ovarian suppression therapy. Since women who undergo chemotherapy are those who are known to have a higher risk of dying from breast cancer, the researchers concluded that “high risk” women should be considered for ovarian suppression therapy.
Women with stage I breast cancers who do not need chemotherapy and women who have small cancers (1 cm or less) without spread to lymph nodes should not receive ovarian suppression.
Another study found that combining ovarian suppression with an aromatase inhibitor instead of with tamoxifen can decrease the chances of dying from breast cancer within 5 years, from 13% to 9%.
Although women taking ovarian suppression therapy with hormone treatment were slightly less likely to die of breast cancer, they did not live longer than women who took hormone therapy alone. In other words, they died of a different cause.
What Are the Potential Harms?
Ovarian Suppression therapy causes symptoms of menopause, because it stops the ovaries from making hormones. There are risks to removing the ovaries by surgery or radiation, such as the risks of anesthesia, infection, bleeding, and damage to nearby organs and tissues.
Removal of ovaries causes early menopause, so a young woman will no longer have periods or be able to get pregnant. Hormone injections can cause hot flashes or flushing, mood changes, depression, sexual dysfunction, and breast changes.
Serious side effects include blood clots, strokes, heart attacks, high or low blood pressure, and brittle or weak bones (osteoporosis).
The Bottom Line
For young pre-menopausal women with estrogen-positive breast cancer, ovarian suppression therapy slightly reduces the chance of dying of breast cancer, but it doesn’t help women live longer. Because the therapy can be harmful with permanent side effects, young women should decide whether the small benefits outweigh the risks. Talk with your doctor about whether the risks outweigh the benefits for you.
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
1. American Cancer Society. Cancer Treatment and Survivorship: Facts and Figures 2016-2017. Available online: https://www.cancer.org
2. Burstein HJ. et al. Adjuvant Endocrine Therapy for Women With Hormone Receptor–Positive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline Update on Ovarian Suppression. Journal of Clinical Oncology. 2017;34(14): 1689-1701. Doi: 10.1200/JCO.2015.65.9573
3. Medscape. Drugs and Diseases: Gosarelin. Available online: https://reference.medscape.