BRCA2 carriers get twice the reduction in breast cancer risk that BRCA1 carriers do, study finds
TUESDAY, Feb. 12 (HealthDay News) -- Women who carry the BRCA1 or BRCA2 mutations that raise the risk for both breast and ovarian cancer should weigh a new finding that suggests having your ovaries removed provides greater protection against breast cancer if you have the BRCA2 mutation.
The preventive strategy has long been contemplated by women in this high-risk category, and this latest research might help women trying to decide whether to have the procedure, said study author Dr. Noah Kauff, a gynecologist, geneticist and assistant attending physician at Memorial Sloan-Kettering Cancer Center in New York City.
"There have been studies that looked at BRCA1 and 2 together, but not 2 alone," Kauff noted. His study is published in the March issue of the Journal of Clinical Oncology.
Women with an inherited BRCA1 or BRCA2 mutation have up to an 80 percent chance of developing breast cancer in their lifetime, according to the American Cancer Society, compared to a lifetime risk of about 12 percent in the general population.
Carriers of BRCA1 or BRCA2 mutations also have an increased risk of ovarian cancer, cancer of the fallopian tubes and another gynecologic cancer called primary peritoneal cancer. The lifetime risk of ovarian cancer for those with BRCA1 mutation is up to 46 percent, and for those with BRCA2 mutations it is up to 27 percent, compared to about a 1.5 percent risk in the general population.
Kauff and his colleagues recruited women from 11 centers across the country in late 2004. For an average of three years, they followed 509 women aged 30 or older who had a BRCA1 or BRCA2 mutation and had the ovary removal surgery (oophorectomy), comparing them with 283 women who also had the mutations but did not elect to have the surgery.
"In the women who elected oophorectomy, if we look at the entire group, 1 and 2 together, we saw that women who had their ovaries removed have an 88 percent reduction in the risk of gynecologic cancer and 47 percent [reduction of risk] in breast cancer," Kauff said.
But when the women with BRCA2 mutations were looked at separately, the researchers found the surgery reduced breast cancer risk by 72 percent -- almost twice as much as the 39 percent reduced risk in BRCA1 mutation carriers -- a reduction that didn't reach statistical significance.
The surgery reduced the risk of gynecologic cancer by 85 percent in women with a BRCA1 mutation, and was suggested in women with BRCA2 mutations, but the researchers were not able to compute the level of reduced risk, because few of these women had those cancers.
When they looked more closely, the researchers found the surgery had a protective effect on the form of breast cancer known as estrogen receptor-positive cancer, reducing risk by 78 percent in both BRCA1 and BRCA2 carriers, but had no effect on ER-negative breast cancers -- which BRCA1 mutation carriers are more likely to get.
"I don't think this is going to have a lot of clinical impact for the average person with a BRCA mutation," said Debbie Saslow, director of breast and gynecologic cancer for the American Cancer Society. "For the average person with BRCA mutation, this probably won't enter into her decision-making." For some, it may confirm surgery is the right thing to do, she added.
The study also raises some questions, said Dr. Angela R. Bradbury, director of the Margaret Dyson Family Risk Assessment Program at Fox Chase Cancer Center in Philadelphia. "This paper raises a question about whether [the surgery] really reduces the risk of ovarian cancer in BRCA2," she said. However, she added, the preventive surgery "still remains the only good option."
To learn more about BRCA1 and BRCA2 mutations, visit the American Cancer Society.
SOURCES: Noah Kauff, M.D., gynecologist, geneticist and assistant attending physician, Memorial Sloan-Kettering Cancer Center, New York City; Angela R. Bradbury, M.D., director, Margaret Dyson Family Risk Assessment Program, Fox Chase Cancer Center, Philadelphia; Debbie Saslow, Ph.D., director, breast and gynecologic cancer, American Cancer Society, Atlanta; March 2008, Journal of Clinical Oncology
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