Women who carry a gene mutation that dramatically increases their risk of breast and ovarian cancers can reduce their chance of dying by nearly 80 per cent if they have their ovaries removed, according to a new Canadian study, which also concludes that the best age at which to undergo the surgery is 35.
The study followed 5,783 women from seven countries with a mutation on their BRCA1 or BRCA2 gene – genes that, when working properly, suppress tumour growth – for nearly six years.
It found that the carriers who had preventive oophorectomies, as ovary-removal procedures are called, reduced by 80 per cent their risk of developing ovarian, fallopian or peritoneal cancer (a rare cancer in the thin layer of tissue that lines the abdomen), and reduced by 77 per cent their risk of dying from all causes – not just cancer.
Oophorectomies also reduce a carrier's risk of developing breast cancer, the study found.
"For me, it's a once-in-a-lifetime finding to see such a dramatic benefit in saving lives that will be immediate upon publication of the paper," said Steven Narod, a senior scientist at the Women's College Research Institute in Toronto and one of the co-authors of the study, published on Monday in the Journal of Clinical Oncology.
Although the benefits of preventive oophorectomies for carriers of a BRCA1 and BRCA2 mutation were already well known, Dr. Narod said he was surprised at how deeply the risk of dying plunged for women who chose the surgery.
"I've written about 300 papers. I never saw anything that reduced mortality of all causes by [more than] 70 per cent. That's just a big number."
The results only fortify the case for undergoing the procedure at the age of 35, he added.
But that recommendation is sure to spark a fraught internal debate for younger carriers of a mutation made famous by actress Angelina Jolie, who last year announced that she had a preventive double mastectomy and is reportedly planning to have her ovaries removed as well.
Carriers who test positive in their 20s or early 30s have to weigh the rewards of having biological children against the risks of ovarian or breast cancer – risks that rise with a woman's age.
The study found that if a carrier of a BRCA1 or BRCA2 mutation puts off an oophorectomy until she is 40, her risk of developing ovarian, fallopian or peritoneal cancer increases to 4 per cent. It rises to 14.2 per cent if she waits until she is 50.
Even for women who do not want children or are done having them, the choice can still be wrenching, because preventive oophorectomies force women into early menopause.
But the upside to the earlier-than-expected hot flashes and risk of bone loss is the peace of mind that comes with taking an effective step to prevent ovarian cancer, a particularly insidious disease.
There is no screening test for ovarian cancer. Symptoms rarely reveal themselves until the cancer is advanced and treatments are limited.
That was such a frightening prospect for Farah Heron, now 37, that the Toronto mother of two opted to have her ovaries removed when she was 35, soon after discovering she had a BRCA1 mutation.
"I was just so utterly terrified of it that I decided to go ahead and do the oophorectomy right away instead of waiting," Ms. Heron said.
"A lot of people had recommended to me to wait until I was in my 40s, but I'm not a person to just kind of wait and see. The anxiety was killing me."
Ms. Heron, who went on to have a preventive double mastectomy as well, was finished having children when she discovered the mutation. Her mother's breast cancer diagnosis prompted the test.
The BRCA1 and BRCA2 mutations are highly hereditary, which means that women who test positive have often watched as breast and ovarian cancers ravaged their mothers, aunts and sisters.
The Canadian Cancer Society estimated that 2,600 Canadian women would be diagnosed with ovarian cancer last year and 1,700 would die of it. Nearly half of those diagnosed last year are expected to survive at least five years.
Only about 10 per cent of those cancers are caused by mutations on the BRCA1 or BRCA2 genes, said Aletta Poll, a genetic counsellor at Women's College Hospital in Toronto.
But for those women who test positive for the mutations, there is a "massive increase" in ovarian cancer risk.
"If you get it, it doesn't tend to end well. This is why, despite the fact that there can be negative consequences, most clinics encourage people to [have an oophorectomy], and a lot of people do consider it," Ms. Poll said.