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Study: Removing Ovaries Substantially Reduces Breast Cancer and Ovarian Cancer Risk for Women with BRCA Gene Mutations (dateline August 19, 2002)

A new study finds that removing the ovaries and fallopian tubes of women who are at genetically high risk of breast cancer and ovarian cancer significantly reduces the likelihood that they will develop either cancer. Researchers have known for years that women who carry abnormal forms of BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) are at higher risk of developing both breast cancer and ovarian cancer, compared to women without these genetic mutations. This is the first time that research has shown that surgery can reduce this risk.

BRCA gene mutations account for approximately 5% of breast cancer cases and approximately 9% of ovarian cancer cases. According to research by the Mayo Health Clinic, 20% of women who carry BRCA1 mutations will develop breast cancer by age 40, over 50% of women with BRCA1 mutations will get the disease by age 50, and over 80% of these women will be diagnosed with breast cancer by age 60. In addition, the lifetime ovarian cancer risk for women with BRCA1 or BRCA2 mutations is estimated to be between 17% and 44%.

To study the effect of surgery on women with BRCA gene mutations, Kenneth Offit, MD and his colleagues from Memorial Sloan-Kettering Cancer Center followed 173 women who had tested positive for mutations of either the BRCA1 or BRCA2 gene. During genetic counseling sessions, the women were told of their increased cancer risk and were given the option of either close monitoring by a physician or surgery to remove their ovaries and fallopian tubes (salpingo-oophorectomy). After considering the choices, 72 decided on close ovarian screening (with transvaginal ultrasound and a CA-125 blood test two times per year) and 101 opted to undergo surgery.

Two years later, 4 cases of cancer had been diagnosed among the women who had had surgery (3 breast cancer cases and 1 peritoneal cancer—ovarian cancer in the surrounding intestinal tissues). By comparison, 13 cancer cases had been diagnosed among the women who had opted for intense screening (8 breast cancer cases, 4 ovarian cancers, and 1 peritoneal cancer). In addition to these cases, three women who underwent the surgery were found to have small ovarian tumors, which according to the researchers, demonstrated the limitations of ovarian cancer screening.

"We now have prospective evidence to present to patients so that they can make informed decisions about their care," said Dr. Offit, Chief of the Clinical Genetics Service at Memorial Sloan-Kettering Cancer Center, in an ASCO statement. The finding was presented at the annual meeting of the American Society of Clinical Oncology (ASCO) in May 2002.

Dr. Offit and his colleagues estimate that the preventive removal of the ovaries and fallopian tubes can reduce the risk of breast cancer and ovarian cancer in women with BRCA gene mutations by as much as 75% compared to intensive ovarian screening.

Since many breast cancer and ovarian cancers depend on the hormone estrogen to grow, removing the ovaries and fallopian tubes reduces these cancer risks since the body’s main source of estrogen is eliminated with the surgery. The researchers say their study finds the preventive surgery a viable option for many women with BRCA gene mutations who are worried about developing cancer because of their family history. Many of these women may be past childbearing age at the time of the surgery.

However, surgery to remove the ovaries and fallopian tubes may not be the best option for all women at high risk of breast cancer and/or ovarian cancer.

Alternative options for women at very high risk of breast cancer include:

Options to help prevent ovarian cancer:

  • Close monitoring with transvaginal ultrasound and CA-125 blood tests (although Dr. Offit’s study found limitations to this method for women with BRCA gene mutations)
  • Taking oral contraceptives
  • Tubal ligation (tying the fallopian tubes) or hysterectomy (removing the uterus)

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