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Prophylactic Surgery Reduces Risk for Women With Abnormal Breast Cancer Genes

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Women with an abnormal breast cancer gene have a much-higher-than-average risk of developing both breast cancer and ovarian cancer. One aggressive option to reduce this risk is to remove the breasts and/or ovaries even though no cancer has been diagnosed. Removing both breasts to reduce risk is called bilateral prophylactic mastectomy. Removing both ovaries (and the fallopian tubes) to reduce risk is called bilateral prophylactic salpingo-oophorectomy. Doctors commonly recommend prophylactic salpingo-oophorectomy for women with an abnormal breast cancer gene. Prophylactic mastectomy is sometimes recommended, too.

You may wonder why removing the ovaries reduces breast cancer risk. Most of the estrogen in women's bodies is made by the ovaries. Estrogen can promote the development, growth, and spread of breast cancer. One drawback of prophylactic salpingo-oophorectomy is that puts premenopausal women into menopause because of the abrupt and permanent drop in estrogen levels.

A study found that women with an abnormal breast cancer gene who had prophylactic salpingo-oophorectomy:

  • lowered their risk of both ovarian cancer and breast cancer
  • improved their chances of living longer, even if they eventually were diagnosed with ovarian or breast cancer

Women with an abnormal breast cancer gene who had prophylactic mastectomy lowered their risk of breast cancer.

Most inherited cases of breast cancer are associated with one of two abnormal breast cancer genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two). Women with an abnormal BRCA1 or BRCA2 gene have up to an 85% risk of developing breast cancer by age 70. Women with an abnormal BRCA1 or BRCA2 gene who already have been diagnosed with breast cancer also have a higher risk of developing a new, second breast cancer compared to women who don't have an abnormal breast cancer gene. Women with an abnormal BRCA1 or BRCA2 gene also have a higher-than-average risk of ovarian cancer.

The study involved 2,482 women with an abnormal BRCA1 or BRCA2 gene that was diagnosed between 1974 and 2008. Some of the women already had been diagnosed with breast cancer, which is why they had genetic testing.

  • 38% of the women had prophylactic salpingo-oophorectomy
  • 10% of the women had prophylactic mastectomy

The women were followed for 3 years after prophylactic surgery. Their health was compared to the health of the women who didn't have prophylactic surgery.

The women who had prophylactic salpingo-oophorectomy reduced their risk of dying from any cause during the 3 years of follow-up and substantially reduced their risk of ovarian cancer and breast cancer.

  • 3% of women who had prophylactic salpingo-oophorectomy died compared to 10% of women who didn't have the surgery
  • 1% of women previously diagnosed with breast cancer who had prophylactic salpingo-oophorectomy were diagnosed with ovarian cancer compared to 6% of women previously diagnosed with breast cancer who didn't have the surgery
  • 2% of women who weren't previously diagnosed with breast cancer who had prophylactic salpingo-oophorectomy were diagnosed with ovarian cancer compared to 6% of women who weren't previously diagnosed with breast cancer who didn't have the surgery
  • 14% of women with an abnormal BRCA1 gene who had prophylactic salpingo-oophorectomy were diagnosed with breast cancer compared to 20% of women with an abnormal BRCA1 gene who didn't have the surgery
  • 7% of women with an abnormal BRCA2 gene who had prophylactic salpingo-oophorectomy were diagnosed with breast cancer compared to 23% of women with an abnormal BRCA2 gene who didn't have the surgery

Women who had prophylactic salpingo-oophorectomy were less likely to die of cancer if they were later diagnosed with either ovarian or breast cancer.

  • the risk of dying after being diagnosed with ovarian cancer was 56% lower
  • the risk of dying after being diagnosed with breast cancer was 79% lower

Women with either abnormal breast cancer gene who had prophylactic mastectomy had a lower risk of breast cancer.

It's understandable that thinking about getting tested for an abnormal BRCA1 or BRCA2 gene may make you anxious. An abnormal breast cancer gene substantially increases your risk of both ovarian and breast cancer. Still, if your personal or family health history suggests that you might have one of these abnormal genes or your doctor recommends genetic testing, it makes sense to consider being tested. Knowing that you don't have an abnormal gene likely will be reassuring. If the results show that you have an abnormal gene, it may be scary, but it will allow you and your doctor to talk about all your options to reduce your cancer risk.

If you do have an abnormal breast cancer gene, prophylactic removal of your ovaries and fallopian tubes is an option that can reduce your risk of both ovarian and breast cancer. Prophylactic mastectomy also can reduce your breast cancer risk.

Decisions about prophylactic surgery require a great deal of thought, patience, and discussion with your doctors, genetic counselors, and family -- plus a tremendous amount of courage. Take as much time as you need to consider these options and make decisions that you're comfortable with and are the best for your unique situation.

Editor’s note: In 2014, a study found that an abnormal PALB2 gene increases breast cancer risk 5 to 9 times higher than average. Research is being planned to see if risk reduction strategies that work for women with an abnormal BRCA1 or BRCA2 gene will work for women with an abnormal PALB2 gene.

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