Oophorectomy Lowers Risk of Breast, Ovarian Ca.
PHILADELPHIA -- Prophylactic, bilateral oophorectomy cuts the overall risk of breast cancer by 63% and ovarian cancer by 90% in women who carry a BRCA1 or BRCA2 mutation.
"The earlier the oophorectomy, the more protective the effect, especially for breast cancer, Dr. Barbara L. Weber said at the annual meeting of the American Society of Human Genetics. "I have no problem recommending oophorectomy at age 30 for an [at-risk] woman who is finished having children," added Dr. Weber, director of the breast cancer program at the University of Pennsylvania Cancer Center in Philadelphia.
Women who undergo oophorectomy at a young age should, in general, receive hormone replacement therapy up to age 50 and then be treated with a selective estrogen-receptor modifier, such as tamoxifen or raloxifene, she said.
The findings regarding risk reduction came from two separate case-control studies that compared the risk of breast or ovarian cancer in women who underwent bilateral oophorectomy and in women who did not. All women in both studies carried either a BRCA1 or BRCA2 mutation.
The study that assessed breast cancer risk included 397 women who had an oophorectomy and 372 women who did not have the procedure; all of these women were aged 30-50.
A preliminary analysis of the data showed that 13 women who had a prophylactic oophorectomy had breast cancer, compared with 33 women who did not have the procedure, so the reduction in breast cancer risk was 63% for women who had an oophorectomy, reported Dr. Andrea Eisen, an oncologist at the Hamilton (Ont.) Regional Cancer Centre.
The study results showed that when oophorectomy was performed in women aged 30-39 years, the risk of breast cancer was reduced by 76%. In women aged 40-49, the risk reduction was 40%.
In the small number of additional women who were aged 50 or older, oophorectomy cut the risk by 6%, which was not statistically significant.
The study that assessed the impact of oophorectomy on ovarian cancer risk included 247 women who had a prophylactic oophorectomy and 249 women who did not.
During a mean 9.4-year follow-up there were 6 cases of ovarian cancer in the women who had an oophorectomy and 34 cases in the women who did not. This worked out to a 90% risk reduction with oophorectomy, reported Dr. Weber.
When the analysis was limited to women who were younger than 50 at the time of the procedure, the risk reduction increased to 94%, she added. The use of hormone replacement therapy had no impact on the risk reduction associated with oophorectomy.
Oophorectomy may be even more effective than these numbers appear to indicate. Four of the six cases of ovarian cancer seen in women who underwent oophorectomy were identified either at the time of surgery or within 3 months after surgery, according to Dr. Weber. The ovarian cancers that appeared in women who already had oophorectomy were peritoneal cancers.
Dr. Weber's aggressive approach to offering early prophylactic oophorectomy was echoed by Dr. Steven A. Narod, chief of breast cancer research at the Centre for Research in Women's Health in Toronto.
"We offer oophorectomy [to high-risk women] as early as age 35, although we wouldn't routinely recommend it earlier," Dr. Narod said at the meeting. "We think that it is better to have oophorectomy followed by hormone replacement therapy. We are also comfortable using unopposed estrogen in women who have also had their uterus removed," said Dr. Narod, who collaborated on both of the studies.
Dr. Weber added that she would recommend oophorectomy to a high-risk woman even if the patient were postmenopausal.
"It doesn't help for breast cancer prophylaxis, but a woman who is 55 or 60 is still at high risk for ovarian cancer. It does not make much sense not to take her ovaries out," Dr. Weber said.