Removing the ovaries may reduce risk of breast and ovarian cancers
Researchers have identified two genes related to breast cancer risk—BRCA1 and BRCA2. It’s estimated that women with a mutation of the BRCA1 gene have a 50% to 85% lifetime risk of developing breast cancer and a 20% to 40% risk of developing ovarian cancer. Women with a BRCA2 gene mutation have about the same breast cancer risk, but a slightly lower risk of ovarian cancer—about 10% to 20%.
Having a prophylactic double mastectomy can nearly eliminate the risk of breast cancer in women with BRCA gene mutations, but many women don’t want to have both breasts removed as a precaution. And because breast cancer is detectable and treatable in it’s early stages, such an extreme measure is considered controversial. Ovarian cancer, however, is not easily detected in its early stages and is generally fatal in advanced stages. For this reason, women with BRCA gene mutations are often advised to have their ovaries removed after their childbearing years to prevent ovarian cancer.
Two new studies reported in a recent issue of The New England Journal of Medicine suggest that women with BRCA1 or BRCA2 gene mutation can vastly reduce their risk of both breast and ovarian cancer by having both ovaries (and sometimes both fallopian tubes) removed as a preventive measure.
About the studies
The two studies were conducted by two separate groups of researchers.
Researchers at New York’s Memorial Sloan-Kettering Cancer Center enrolled 170 women age 35 and older with BRCA1 or BRCA2 gene mutation. At the start of the study, all of the women were free of breast and ovarian cancer and had no history of either cancer. Ninety-eight women chose to undergo surgery to remove both ovaries and both fallopian tubes in the hopes of preventing ovarian and breast cancers. Seventy-two women chose surveillance, which means their doctors monitored them closely for signs of ovarian and breast cancer. Surveillance involved yearly or twice-yearly gynecologic exams, transvaginal ultrasounds, CA-125 tests, mammograms, and clinical breast exams. These women were followed for an average of two years, during which time they answered annual questionnaires about their medical status and researchers reviewed their medical records.
In this study, researchers compared the number of breast and ovarian cancer cases that developed among women who had the surgery with the number of cases among women who did not have surgery.
In a separate study, researchers from the U.S., Canada, the United Kingdom, and the Netherlands examined the rate of breast and ovarian cancers among 551 women with BRCA1 or BRCA2 mutation. In this study, 259 of the women had already undergone surgery to remove their ovaries and 292 had chosen not to have the surgery. Women who had chosen not to have surgery were matched by age at time of surgery to a woman who did have surgery. None of the women had a history of ovarian cancer at the time of surgery. The researchers used medical records, telephone interviews with participants, and questionnaires to determine which women had developed breast or ovarian cancer. The average length of time that the women were followed-up after surgery (or from the date of their matched control’s surgery) was about 8 years.
As in the first study, these researchers compared the number of breast and ovarian cancer cases among women who had undergone surgery with the number of cases among women who had not.
In the Memorial Sloan-Kettering study, women who had surgery to remove their ovaries and fallopian tubes were 75% less likely to develop breast or ovarian cancer than women who did not have the surgery.
Although these results are interesting, there are limitations to this study. The women in this study were only followed for an average of about two years (range: less than one year to 6 years). In addition, the researchers measured the number of cancer cases and the time to cancer development, but not the survival rate. These measures do not take into account the other health risks presented by having the ovaries removed, such as heart disease, stroke, and osteoporosis. Because surgical removal of the ovaries is fairly common among women with a BRCA mutation, the women could not be randomly assigned to either surgery or surveillance. Random assignment helps reduce the likelihood that one study group is different from another in ways that may affect the outcome of the study.
In the study by the international group of researchers, women who had surgery to remove their ovaries were 96% less likely to develop ovarian cancer and 53% less likely to develop breast cancer than women who did not have the surgery.
Although these results corroborate the results of the first study, there are limitations to this study, too. Because the women in this study had already undergone surgery or not, the researchers were not able to randomly assign them to either surgery or surveillance. Random assignment helps reduce the likelihood that one study group is different from another in ways that may affect the outcome of the study. Like the Memorial Sloan-Kettering study, this study did not assess a woman’s risk of developing conditions associated with ovary removal, such as heart disease, stroke, and osteoporosis.
How does this affect you?
Should you have your ovaries and fallopian tubes removed if you have a BRCA gene mutation? That’s something you’ll need to talk over with your doctor. The findings of these two studies add to mounting evidence that removal of the ovaries (and possibly fallopian tubes) after the childbearing years is an effective way to reduce the risk of both ovarian and breast cancers in carriers of BRCA mutations. In fact, this surgery is currently recommended for women with BRCA mutations.
Based on these findings and the findings of previous studies, the authors and independent reviewer, Dr. Daniel Haber of Massachusetts General Hospital in Boston, support surgical removal of the ovaries and fallopian tubes after the childbearing years among women with BRCA gene mutations.
Of note is that the authors don’t define what age range comprises your “child-bearing years.” This is a personal decision based on your fertility expectations and whether or not you want to have more children.
These surgeries are not to be taken lightly, though. Talk to your doctor about your specific situation. And don’t be afraid to get a second opinion. This an important decision about your health and your life, so make sure you are comfortable with the potential complications and side effects. For example, without the ovaries to produce estrogen, women who have had their ovaries removed are immediately thrust into menopause, which puts you at increased risk for heart disease and osteoporosis. On the other hand, the peace of mind that comes with lowering your risk of two aggressive cancers may be worth the “menopause factor.”
Kauff ND, et al. Risk-reducing salpingo-oophorectomy in women with a BRCA1 or BRCA2 mutation. New England Journal of Medicine . May 23, 2002;346(21):1609-1615.
Rebbeck TR, et al. Prophylactic oophorectomy in carriers of BRCA1 or BRCA2 mutation. New England Journal of Medicine . May 23, 2002;346(21):1616-1622.
Haber D. Prophylactic oophorectomy to reduce the risk of ovarian and breast cancer in carriers of BRCA mutations. New England Journal of Medicine . May 23, 2002;346(21):1660-1662.
Last reviewed May 22, 2002
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