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TUESDAY, Feb. 11, 2014 (HealthDay News) -- Women diagnosed with an inherited form of breast cancer might halve their risk of dying of the disease if they remove both breasts, a new study suggests.
"I think we've shown pretty clearly that if you have breast cancer and the BRCA mutation, your best option is to get both breasts removed at the outset," said study author Dr. Steven Narod, a senior scientist with the University of Toronto's Women's College Research Institute, in Canada.
The research, published in the Feb. 11 issue of the journal BMJ, is the first evidence that shows having a so-called bilateral mastectomy actually saves the lives of women with early stage breast cancer and mutations in their BRCA genes, the study authors said.
But some doctors not involved with the study said the conclusions may be a bit premature.
Angelina Jolie brought new attention to gene testing for breast cancer last May when she announced she carried a mutation in her BRCA1 gene and was removing both breasts with the hope of avoiding her mother's fate. Her mother, Marcheline Bertrand, died of cancer at the age of 56. She had been battling breast and ovarian cancer for 10 years.
On average, about 12 percent of women will get breast cancer over the course of their lives. But for women who carry BRCA mutations, the lifetime risk jumps to 60 percent to 70 percent, according to background information included in the study. They're also more likely to get cancer at younger ages and to be diagnosed with more aggressive forms of the disease.
Such mutations are rare, however. They're estimated to account for about 5 percent to 10 percent of all breast cancers, according to the study.
For women who only discover that they carry the defective genes after they've been diagnosed with cancer, it's been unclear whether removal of the opposite breast actually improves their chances of survival.
The new study traced the cancer histories of nearly 400 women with stage 1 and stage 2 breast cancer who were diagnosed between 1977 and 2009. All the women came from families known to have mutations in their BRCA1 or BRCA2 genes. Most of the women had tested positive for a mutation themselves, and were diagnosed with cancer in their early 40s. They were followed for an average of 13 years.
When it came time for surgery, 209 women opted to remove only the breast affected by the cancer, while 181 had both breasts removed.
Over the course of the study, 79 women died of breast cancer -- 61 in the group that had only one breast removed and 18 in the group that had both breasts removed.
After controlling for other factors that might influence survival -- such as tumor size, age at diagnosis and whether the cancer had spread to the lymph nodes -- researchers found that having both breasts removed reduced a woman's chances of dying of breast cancer by 48 percent during the next 20 years.
The researchers said bilateral mastectomy seemed to do the most good in the second decade after diagnosis.
"If you have breast cancer and a BRCA mutation -- and if you're going to die of that breast cancer -- you'll likely die in the first 10 years," Narod said. "After the 10 years are up, in most cases, you should consider yourself cured of breast cancer."
"What that means is that women who died between years 10 and 20 didn't die of the first breast cancer, they died of a new [cancer], and you can prevent that," he said.
Narod said his study underscores the importance of genetic testing, especially for women who are diagnosed at a young age or who have a strong family history of the disease. For them, a positive genetic test should help guide treatment decisions.
Not all experts agree that this study is the last word, however.
Karin Michels, an epidemiologist at Brigham and Women's Hospital in Boston, said the decision to remove both breasts is a difficult choice for many women, and one that should be carefully considered.
"It's a very personal decision," said Michels, who wrote an editorial on the study. "I think we cannot just say, 'Here are the statistics: It's a no-brainer.' I think it's not a no-brainer."
For one thing, Michels said, the study was small. It was also an observational study -- not the preferred double-blind, placebo-controlled study. There may have been important differences between the study groups that researchers weren't able to account for, and those differences may have played a bigger role in survival than their choice of surgery.
"If we have more and larger studies, they will probably confirm these results, but it's a little premature to say this," Michels said. "It's good evidence, but it's not superb evidence."
For those who aren't ready to part with both breasts, experts say there are other options.
"We get a lot of women who are diagnosed, and they're young and they get sent to us for fast-turnaround BRCA testing so they can make treatment decisions," said Dr. Mary Daly, chairwoman of cancer genetics at Fox Chase Cancer Center in Philadelphia. "At a time of so much emotion and chaos, I'm not sure they always make the best decision."
"This article sort of shows you that if you're not quite ready to make that decision at the time of the initial diagnosis, you can still go back and remove the other breast later and it probably will still be effective," Daly said.
Only 44 women in the study had both breasts removed at the same time. Another 137 women chose to have their unaffected breast removed at a later date. On average, women removed their second breast about two years after their diagnosis.
Beyond removal of the breasts, Daly said there are other treatments that can help women with BRCA mutations. Those include removal of the ovaries, which also decreases the chances of breast cancer; preventive medications such as tamoxifen; and intensive monitoring with yearly mammograms and MRIs.
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SOURCES: Steven Narod, M.D., senior scientist, Women's College Research Institute, University of Toronto, Canada; Karin Michels, Sc.D., Ph.D., associate professor and co-director, The Ob-Gyn Epidemiology Center, Brigham and Women's Hospital, Boston; Mary Daly, M.D., Ph.D., chairwoman, cancer genetics, Fox Chase Cancer Center, Philadelphia; Feb. 11, 2014, BMJ