Women who are considering getting their fallopian tubes tied should instead have them removed altogether, some doctors say. And, they add, perhaps even women undergoing any type of abdominal surgery should also have their tubes removed, as long as they don't want any more children.
That's because recent research suggests a woman's fallopian tubes are the true source of some of the deadliest ovarian cancers, and removing them could lower her risk of developing the disease.
"The research supports the possibility that the fallopian tube could be thought of as a target for prevention," especially in women who are having surgery anyway for other reasons, said Dr. Robert Burger of Fox Chase Cancer Center in Philadelphia, where he is the associate director of gynecologic cancer research.
In fact, doctors in British Columbia now routinely discuss removing the tubes with all women who've completed child-bearing and are having pelvic or abdominal surgery, such as a hysterectomy, said Dr. Jessica McAlpine, a gynecologic oncologist at Vancouver General Hospital and the British Columbia Cancer Agency. Statements issued from the Society of Gynecologic Oncologists of Canada indicate such discussion takes place across Canada.
"It’s a much more conservative approach here" in the United States, Burger said, "and we pay for it. When this type of cancer develops, the mortality rate is so high, it's second only to pancreatic cancer."
There are genes, such as BRCA1 and BRCA2, that raise a woman's risk of developing what are known as high-grade serous ovarian tumors, but 90 percent of the cases show no clear genetic link to the disease.
"To add a minimal-risk surgery to an operation that’s already being performed — to me, it’s a no-brainer," Burger said. "And most women have no idea about this."
Out of tubes, into the ovaries
The National Cancer Institute estimates 22,280 women will be diagnosed with ovarian cancer this year, and 15,500 women will die of the disease. "Over 75 percent of ovarian cancers are high-grade serous cancers," the deadliest ovarian cancers, Burger said.
Research in the 1990s led to the discovery that some of these cancers begin in tube cells a short distance from the ovaries. Shortly after it was learned that women with mutations in the BRCA genes were at increased risk of ovarian cancer, these women were offered prophylactic surgery to remove their fallopian tubes and ovaries.
By the mid-2000s, pathologists studying the removed tissues began to report cases in which early cancers were visible in the very ends of the fallopian tubes but not in the ovaries.
"We thought maybe this is the source," Burger said.
Then in 2007, a major paper published in the Journal of Pathology took a close look at the genes of ovarian cancer cells — from women with and without BRCA mutations — and determined that the fallopian tubes were the true site of origin for many ovarian cancers. Research showed how normal fallopian tube cells evolved into early cancers and then into invasive cancers — a process that had eluded researchers focused on the ovary itself.
Studies since then have suggested that 50 percent to 84 percent of high-grade serous tumors arise from the tubes, said Dr. Ronny Drapkin, an assistant professor of pathology at Harvard Medical School, and one of the authors of that study.
Different risk levels
The findings have different implications for women depending on how high a risk they are at for ovarian cancer.
Women in the general population, who are not at a high risk of ovarian cancer or who don't know their risk, "should seriously consider having their tubes removed" if they have completed childbearing and are having any abdominal surgery, Burger said. And post-menopausal women in this group should consider having both their ovaries and tubes removed, he said.
Drapkin and McAlpine agreed, and Drapkin said he recently recommended to his sister, who was planning to have a hysterectomy, that she have her fallopian tubes removed during the operation. (She did.)
There are risks that come with removing the fallopian tubes, a procedure called a salpingectomy. The main worry is that the blood supply to the ovaries will be cut off, Drapkin said. During an operation, surgeons cauterize blood vessels, and the anatomy in that part of the body is complicated. An operation aimed at removing only the tubes "could compromise the viability of an ovary," he said. And of course, there are risks anytime a person is put under general anesthesia, Drapkin added.
For women at high risk for the disease, the situation is quite different, as they are currently offered surgery to remove both the ovaries and the fallopian tubes once they complete childbearing, Drapkin said. But these operations send women into early menopause, which brings its own health risks, such as an increased risk of cardiovascular problems and bone disease, he said.
"The question has become, should we just be removing the tubes instead?" Drapkin said. The idea that's floating around among experts is that high-risk women could have their tubes removed once they're done having children. Then, after natural menopause, the ovaries could be removed as well.
But leaving in the ovaries is a scary proposition for some. While the evidence shows that a majority of the cancers arise from the tubes, there isn't evidence that all do, Drapkin said. "The worry is, what if we miss one? It's not like breast cancer or colon cancer — there's no screening tool, and it’s a potentially lethal disease."
Other unknowns include whether high-risk women who opt to retain their ovaries are depriving themselves of the protective benefit against breast cancer that comes from ovary removal, McAlpine said.
Until more studies are done, the decision is highly individual and can depend on the age at which other women in the family developed ovarian cancer, as well as a woman's own age, she said. It may make more sense for a 30-year-old than for a 45-year-old to leave her ovaries in.
Will tube removal become common?
Among researchers and physicians, there has been "more widespread acceptance, and general awareness, over the last one to two years" of the evidence that these ovarian cancers arise in the fallopian tubes, McAlpine said.
But what's being done about it "varies from nothing to tentative" action, she said.
McAlpine recently examined a database of ovarian cancer cases in British Columbia, looking at the numbers of women who had undergone a hysterectomy or tubal ligation (tube-tying) prior to developing cancer, and at the rate of referral to genetic counselors and surgeons for women at high risk of the cancer.
She estimated that 40 percent of ovarian cancer cases in British Columbia could be prevented if the fallopian tubes were removed from every woman with BRCA mutations or were undergoing a hysterectomy or tubal ligation. A similar result would be likely in the U.S., where the rate of women undergoing tubal ligation is about the same and the hysterectomy rate is slightly higher, she said.
What needs to be done, all of the experts said, is a clinical trial.
A study of women who aren't at high risk is likely to come first, Drapkin said. For example, researchers could look at women having hysterectomies, and compare the rates of ovarian cancer between those who also had their tubes removed and those who didn't.
Burger added that the new understanding of ovarian cancer could lend itself to a renewed search for ways to screen for the disease. Pelvic exams, transvaginal ultrasounds, and blood tests that look for a molecule called CA-125 have all been tried, but none has proven effective in catching cancer cases early.
"We really need to study the fallopian tubes to pick up the abnormalities," Burger said. Researchers should look for ways to examine the tubes "almost like colonoscopies."