(February 29, 2012)

Q: Is it true that ovarian cancer may start in the fallopian tubes? Will having a tubal ligation lessen my chance of developing it? I have a family history of the disease and am a BRCA1 carrier.

A: Recent research suggests that some of the cells that may form one type of ovarian cancer come from the fallopian tubes. Other research has consistently shown that tubal ligation decreases the risk of developing ovarian cancer. But it's not clear if those findings are related.

The ovaries are almond-shaped organs on each side of the uterus that contain eggs and make the hormones that control a woman's reproductive cycle. The fallopian tubes are the passages through which eggs travel from the ovaries to the uterus. The fimbria is a fringe around the opening of a fallopian tube, in the direction of the ovary, but not attached to the ovary.

Ovarian cancer can begin in cells located on the tissue that covers the outside of the ovary, in the egg-producing cells within an ovary, or in an ovary's hormone-producing cells. Most ovarian cancers begin on the outside cells. When investigating a possible link between the fallopian tubes and ovarian cancer, researchers examined the cells on the fallopian tube fimbria in women who had the BRCA1 or BRCA2 gene mutation. These gene mutations put women at high risk for breast and ovarian cancer.

Researchers found that a significant percentage of women in the study had abnormal cells in the fallopian tube fimbria that were precancerous or cancerous. This research suggests the possibility that, rather than beginning in cells on the ovary's outside layer, ovarian cancer on the surface of the ovary may come from cancerous cells originating in the fimbria.

Based on this information, researchers and doctors are now considering if they should routinely examine the tissue of the fallopian tubes, especially in women who have the BRCA1 or BRCA2 gene mutation. Discussion is also under way regarding the possibility of removing the fallopian tubes, or perhaps just the fimbria, as a way to reduce the risk of ovarian cancer.

In a tubal ligation procedure (also known as "having your tubes tied") the fallopian tubes are cut or blocked permanently, preventing eggs from traveling from the ovaries to the uterus. Because tubal ligation may not have a direct impact on the fimbria, it is not clear if the procedure would affect the transfer of abnormal cells from the fimbria to the ovaries.

However, other research has shown that tubal ligation substantially lowers a woman's risk of ovarian cancer. Researchers are not sure exactly why. Some suspect that tubal ligation cuts off the ovaries' exposure to outside environmental factors that may increase the risk of ovarian cancer. Others think it could be related to the anatomical changes in the fallopian tubes that happen after a tubal ligation.

Because you carry the BRCA1 gene mutation, a discussion with your doctor decreasing your risk would definitely be worthwhile. A discussion should include risks, benefits and possible alternatives.

Ovarian cancer resource

For more information about ovarian cancer, including causes, symptoms and risk factors, go to mayoclinic.com (type "ovarian cancer" in the search field).

Paul Haluska, M.D., is a medical oncologist at Mayo Clinic in Rochester, Minn.

Distributed by Tribune Media Services