B.C. researchers are urging gynecologists to remove a woman’s fallopian tubes during a hysterectomy or tubal ligation as a means of preventing ovarian cancer, one of the deadliest malignancies affecting Canadian females.
Researchers from the B.C. Cancer Agency and Vancouver General Hospital are asking all gynecologists in the province — and indeed across Canada — to change the standard surgical practice of leaving the fallopian tubes intact when performing the surgeries.
The fallopian tubes, the conduits for eggs between the ovaries and the womb, have typically been left in place because doctors saw no reason to remove the structures when taking out the uterus, especially if the ovaries were also left untouched.
In a tubal ligation — or getting one’s “tubes tied” — the fallopian tubes are not removed but severed and sealed or clamped shut to prevent conception.
But Dr. Sarah Finlayson, a gynecological oncologist at Vancouver General, said recent research has shown that at least half of the cases of the deadliest form of ovarian cancer originate in the fallopian tubes — not the ovaries.
That malignancy, called a high-grade serous tumour, represents about 70 per cent of all ovarian cancers.
And because there is no screening test and symptoms can be non-existent or vague, diagnosis too often occurs once the cancer is at an advanced stage and has spread to other tissues.
“Something that we had thought of in the past as an ovarian cancer is really, in fact, a fallopian tube cancer,” said Finlayson.
“Removing the fallopian tube becomes a way of preventing these cancers.”
The Canadian Cancer Society estimates that 2,600 Canadian women will be diagnosed this year with ovarian cancer of one form or another; about 1,750 will die of the disease.
High-grade serous carcinoma is the most common form of ovarian cancer, accounting for 90 per cent of advanced-stage ovarian cancer.
Finlayson said most post-menopausal women who have a hysterectomy have their fallopian tubes taken out along with their ovaries, which stop producing estrogen over time.
“So it’s really the pre-menopausal women we’re interested in talking to or getting this information out to — women who are having hysterectomy prior to the menopause,” she said.
The surgery is done for a number of reasons, including fibroids, endometriosis and malignancies.
Researchers aren’t sure why tumours arise in the fallopian tubes.
But they speculate that an infectious or inflammatory process may occur during a woman’s monthly period that sets up a repeated process of injury and repair, eventually leading to cancerous lesions.
“So we believe that probably at the time of the hysterectomy, the die has been cast,” she said.
“The point is to take out the fallopian tube before whatever damage leads to a pre-cancer or a cancer ... and then spreads.”
The research team, which is made up of surgeons, oncologists and pathologists, also made another important discovery: they found one in five serous tumours occur because a woman carries a BRCA genetic mutation. Women with a BRCA1 or BRCA2 mutation have an elevated risk of developing breast and-or ovarian cancer.
“What this means is that in 20 per cent of cases, we are discovering the index case,” Dr. Blake Gilks, a pathologist with B.C.’s Ovarian Cancer Research Program, said in a statement.
“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.”
That’s why, Finlayson noted, the researchers want every women diagnosed with a high-grade serous tumour to be referred to the B.C. Cancer Agency for genetic testing and counselling.
These two steps — changing practice to remove the fallopian tubes and genetic testing — “will allow us to decrease the rate of ovarian cancer in B.C. by up to 50 per cent over the next two decades,” she said.
“The ability to do surgery for prevention is going to rest with gynecologists who see women before cancer develops,” said Finlayson, who hopes to see a national strategy within the next year for getting the message across to women and their doctors.