Deaths from ovarian cancer could be reduced by half with a simple change in routine gynecological surgery, B.C. researchers have discovered, and they have launched a campaign to alert doctors and patients to the new approach.
Removing fallopian tubes as part of hysterectomies and tubal ligations would "have an immediate impact on saving lives," said Dianne Miller, a gynecologic oncologist with the Ovarian Cancer Research Program of the B.C. Cancer Agency.
That is because, paradoxically, the most deadly form of ovarian cancer originates in the fallopian tubes - where eggs travel from the ovaries to the womb - not the ovaries per se, she said.
"This was a eureka moment for us," Dr. Miller said.
Current practice calls for the uterus to be removed during a hysterectomy. In women whose ovaries are still functioning, fallopian tubes are conventionally left in place. (In postmenopausal women and those with a genetic predisposition to ovarian cancer, on the other hand, the uterus, ovaries and fallopian tubes are all removed.)
In tubal ligation - getting "tubes tied" in common parlance - the tubes are sealed or severed to prevent conception, but they are not removed. There are about 50,000 hysterectomies performed in Canada annually, and another 20,000 tubal ligations.
Sarah Finlayson, a gynecologic oncologist at the Ovarian Cancer Research Program, said the findings have important implications and need to be widely publicized among clinicians, surgeons and patients groups.
"We are hoping this information goes viral," she said in an interview. "We don't want to own this in B.C. We just want women to know this."
Dr. Finlayson said the discovery came out during research into the genetic causes of ovarian cancer. It is already well established that women with the genetic mutations BRCA1/2 (often called the breast-cancer genes) have a dramatically higher risk of developing ovarian cancer. Many have their ovaries and fallopian tubes removed, in addition to their breasts, to prevent cancer.
"We looked at those ovaries and fallopian tubes under the microscope and discovered we were finding early pre-cancers not in the ovary, but in the fallopian tubes," Dr. Finlayson said.
That led researchers to wonder if the same was true of women without the genetic mutation, and it was. The majority of high-grade serous tumours, the most deadly form of ovarian cancer, were actually in the tubes.
"The studies showed, 'Oh my goodness, these aren't ovarian cancers, these are fallopian tube cancers.' And that was the moment we realized we could do something," Dr. Finlayson said.
The data also showed that 18 per cent of ovarian cancer occurred in women who had previously undergone a hysterectomy.
Researchers said it is not clear why cancerous tumours develop in the fallopian tubes, but it may be due to the inflammatory process that occurs during the menstrual cycle.
In a related development, the same research team - made up of surgeons, oncologists and pathologists - also found one in five serous cancer tumours occur because of a germline BRCA genetic mutation.
"What this means is that in 20 per cent of cases, we are discovering the index case," said Blake Gilks, a professor of pathology and laboratory medicine at the University of British Columbia.
"A woman may have no prior history of ovarian cancer in her family, but we now know that her children and their children could be at risk, and we have the ability to screen them genetically and act proactively," he said.
Dr. Finlayson said that changing surgical practice and routinely removing fallopian tubes can reduce ovarian cancer deaths by about 30 per cent, and pro-actively following families who have the BRCA gene mutation can cut deaths by another 20 per cent - a 50-per-cent reduction in total. Researchers said this reduction would likely occur over a period of about 20 years.
An estimated 2,600 Canadian women were diagnosed with ovarian cancer and 1,750 women died from the disease in 2009, according to estimates by the Canadian Cancer Society. It is one of the most deadly forms of cancer, with a five-year survival rate of only 37 per cent.