Gene mutations known to increase a woman's risk of getting breast cancer do not appear to also worsen her chance of survival after a diagnosis, a new study suggests.
The findings should be reassuring to women with breast cancer, as carrying the BRCA1 mutations is "not a death sentence," provided patients get good treatment, Dr. Pamela Goodwin, an oncologist from the Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital in Toronto, said.
The study backs up earlier reports showing BRCA1 mutations do not predict cancer survival, researchers said.
What is new is that women with the mutations seemed to benefit much more from ovary removal surgery than those without BRCA1 mutations, senior author Dr. Steven Narod of Women's College Research Institute in Toronto, said.
He and his colleagues tested more than 3,300 Polish women younger than 50 years old with recently diagnosed breast cancer for three specific mutations in the BRCA1 gene, starting in 1996.
Of those women, 233 tested positive for so-called founder mutations in BRCA1.
Founder mutations are a handful of specific changes repeatedly found among people of a particular ethnicity or from a particular region, which presumably date back hundreds of years to a single individual, Dr. Ellen Warner, a breast cancer researcher at the Sunnybrook Health Sciences Center in Toronto, told Reuters Health in an email.
The researchers found 81 percent of women with a BRCA1 mutation lived for at least 10 years after their diagnosis, similar to the 82 percent survival rate among mutation-free women.
Lymph node status - whether cancerous cells were found in lymph nodes under the arm at diagnosis - was a much better predictor of survival. Women with positive lymph node status were three times more likely to die over the same period than those whose cancer had not spread to the nodes.
Among women carrying the BRCA1 mutations, those who had surgery to remove their ovaries, called oophorectomy, were 70 percent less likely to die during the study than mutation carriers who did not have surgery.
Most of those surgeries were done after women were diagnosed with breast cancer.
Women without BRCA1 mutations, on the other hand, did not appear to benefit from ovary removal, according to results published in the Journal of Clinical Oncology.
One in 300 to one in 500 women has a BRCA1 or BRCA2 mutation. According to the National Cancer Institute (NCI), a woman's chance of getting breast cancer increases from 12 to between 45 and 65 percent if she carries one of those mutations.
Goodwin, who wasn't part of the study team but published similar results last year, advocates genetic testing for women with at least a 10 percent chance of being a mutation carrier based on their medical and family histories. That is the standard in most countries, she said.
"It's not clear that everyone (with breast cancer) should be tested at diagnosis," Goodwin said. "A 70-year-old woman with no family history should probably not be tested for the mutation."
Narod said the results of the study suggest all women diagnosed with breast cancer before age 50 should be tested for BRCA1 mutations, and those who are carriers should have their ovaries removed within three months.
For women with a BRCA mutation, the risk of ovarian cancer also increases, from 1.4 percent to between 11 and 39 percent, according to the NCI.
Goodwin cautioned that in the case of this study, women who lived long enough to have an oophorectomy may have had more treatable breast cancers to begin with. It's possible they wouldn't have had as many cancer recurrences or early deaths regardless of the surgery, she said.
"I suspect there may be some benefit, but I'm not sure it's a full 70 percent reduction in risk," she said.