Women with a BRCA genetic mutation who have their ovaries and fallopian tubes removed preventively — called prophylactic bilateral salpingo-oophorectomy — are likely to have lower bone density after surgery, especially if a woman is premenopausal at the time of surgery, according to a study.
The research was published online on Aug. 7, 2019, by the journal JAMA Network Open. Read the abstract of “Changes in Bone Mineral Density After Prophylactic Bilateral Salpingo-Oophorectomy in Carriers of a BRCA Mutation.”
Gene mutations linked to breast cancer
Two of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1 and BRCA2. Women who inherit a mutation in either of these genes — from their mothers or their fathers — have a much higher-than-average risk of developing breast cancer and/or ovarian cancer.
Men with these mutations also have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer.
About 5% to 10% of breast cancers are thought to be hereditary, meaning the cancer is linked to mutations in genes passed from parent to child.
You are substantially more likely to have a genetic mutation linked to breast cancer if:
- You have blood relatives (grandmothers, mother, sisters, aunts) on either your mother's or father's side of the family who had breast cancer diagnosed before age 50.
- There is both breast and ovarian cancer on the same side of the family or in a single individual.
- You have a relative(s) with triple-negative breast cancer.
- There are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, and/or sarcoma.
- Women in your family have had cancer in both breasts.
- You are of Ashkenazi Jewish (Eastern European) heritage.
- You are African American and have been diagnosed with breast cancer at age 35 or younger.
- A man in your family has had breast cancer.
- There is a known breast cancer gene mutation in your family.
Preventive ovary removal
Women who are at high risk for breast cancer and/or ovarian cancer because they have a BRCA mutation may choose to have their healthy breasts and/or ovaries removed. Prophylactic bilateral salpingo-oophorectomy surgery means that both ovaries and fallopian tubes are removed before cancer is detected in them. The ovaries are the body’s main source of the hormones estrogen and progesterone. The fallopian tubes connect the ovaries to the uterus.
According to the National Cancer Institute, removing both the ovaries and the fallopian tubes preventively can reduce the risk of ovarian cancer by about 90% and the risk of breast cancer by about 50% in women at high risk for the diseases.
Although prophylactic ovary removal can significantly reduce the risk of developing ovarian cancer — and also reduce the risk of breast cancer — this surgery is a serious choice that can have a considerable impact on your life. The sudden loss of estrogen can cause a range of side effects, such as hot flashes, depression, difficulty sleeping, and lessened sex drive. Estrogen loss may also affect bone and heart health. Ovary removal also takes away your ability to have children.
How this study was done
While doctors know that the loss of estrogen that happens after the ovaries are removed can affect a woman’s bone health, not much research has been done on the subject.
This Canadian study included 95 women with a confirmed BRCA mutation who had prophylactic bilateral salpingo-oophorectomy between January 2000 and May 2013:
- 50 of the women were premenopausal before surgery, and 45 were postmenopausal
- average age at surgery was 48 years
- 16 women had only bilateral salpingo-oophorectomy; 79 women had bilateral salpingo-oophorectomy and a hysterectomy, meaning they also had the uterus removed
- 43 women had a history of breast cancer, including 14 premenopausal women and 29 postmenopausal women
- 32 of the 43 women with a history of breast cancer were treated with chemotherapy
- 47 women had a BRCA1 mutation
- 48 women had a BRCA2 mutation
The women’s bone mineral density was measured using a DEXA scan before the surgery to remove the ovaries and fallopian tubes and then about 1 year after surgery.
Also called dual-energy X-ray absorptiometry, a DEXA scan uses low levels of X-rays to measure bone density. Using a DEXA scan to measure bone mineral density at the hip and spine is considered the most reliable way to diagnose osteoporosis and predict the risk of breaking a bone.
DEXA scan results are in the form of two scores:
- T-score: The T-score is the difference between a woman’s bone density and the average bone density of a young, healthy woman. A score above −1 is considered normal. A score between −1 and −2.5 is classified as osteopenia, and a score below −2.5 is classified as osteoporosis.
- Z-score: The Z-score is the amount of bone a woman has compared to other women of her age and race.
The researchers also collected information on the women’s:
- history of child birth
- menopausal status
- cancer history
- surgical history
- use of any medicines, including hormone replacement therapy
- smoking status
- physical activity
- use of tamoxifen and/or aromatase inhibitors
Before preventive surgery, DEXA scan scores found:
- 52 women had normal bone density
- 39 women had osteopenia, or lower-than-normal bone density
- 4 women had osteoporosis, or bone density so low they were at high risk of breaking a bone
After preventive surgery, DEXA scan scores found:
- 38 women had normal bone density
- 51 women had osteopenia
- 6 women had osteoporosis
Overall, all the women had a decrease in bone mineral density after surgery, but the decrease was greatest in the premenopausal women. Women who were premenopausal before preventive surgery who took hormone replacement therapy after surgery had less bone loss than women who didn’t take hormone replacement therapy.
“Although [hormone replacement therapy] minimized the amount of [bone mineral density] loss, it did not completely prevent postsurgery bone loss,” the researchers wrote. “These findings strongly support including routine monitoring of [bone mineral density] in this high-risk population and recommending adequate calcium intake, weight-bearing exercise, and the use of [hormone replacement therapy] among those without a history of breast cancer.”
What this means for you
If you know you have a BRCA mutation, you may be considering taking steps to keep your risks of breast and ovarian cancer as low as they can be. There are many lifestyle choices you can make, including:
- maintaining a healthy weight
- exercising regularly
- limiting alcohol
- eating nutritious food
- never smoking
You also may be considering preventive ovary and fallopian tube removal. As this study shows, in addition to side effects from the loss of estrogen after the ovaries are removed, the surgery also can affect your bone health.
If you’ve had or will be having preventive ovary and fallopian tube removal surgery, there are lifestyle changes you can take to keep your bones as healthy as they can be:
- get enough calcium
- get enough vitamin D
- do weight-bearing exercise
- limit or avoid alcohol
- quit smoking
There are also a number of medicines you can take to help prevent bone loss, including bisphosphonates, selective estrogen receptor modulators, and targeted therapies.
For more information on bone loss and ways to keep your bones strong, visit the Breastcancer.org Bone Health pages.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser