Lynch syndrome, also called hereditary nonpolyposis colon cancer, is an inherited disorder in which affected individuals have a much higher-than-normal chance of developing colon cancer and/or certain other types of cancer, usually before the age of 60. About one in 1,000 individuals carry the gene mutation that causes Lynch syndrome, which accounts for approximately five percent of all colon (in men and women) and endometrial cancers, and two percent of all ovarian cancers, according to Karen Lu, M.D., associate professor in M. D. Anderson's Department of Gynecologic Oncology.
"The key reason that we embarked on this study was that women with Lynch syndrome have an equal risk of developing endometrial and colon cancers, and often develop additional cancers. However, for the last 20 years, the majority of the Lynch syndrome research has been focused on colon cancer risk. Often, women who have this condition don't even realize that they also are at risk for two gynecological cancers, and their risk is extremely high."
Women with the condition have a 40 percent to 60 percent lifetime risk of developing endometrial cancer, and a 10 percent to 12 percent lifetime risk of ovarian cancer, says Lu, the study's corresponding author. By comparison, in the general population, a woman's risk of developing endometrial cancer is about three percent, and a woman's risk of developing ovarian cancer is one percent to two percent.
To determine that the preventative surgeries reduced the risk for endometrial and ovarian cancers, Lu and her colleagues retrospectively evaluated 315 women with Lynch syndrome. For preventative reasons or to treat benign conditions, 61 of these women had undergone a prophylactic hysterectomy; 47 also had their ovaries removed. All of the other 254 women, the control group, had not undergone any prophylactic surgeries.
No endometrial and/or ovarian cancers were diagnosed in the women who had undergone the prophylactic surgeries. However, 69 women (33 percent) in the control group were diagnosed with endometrial cancer; 12 women (5 percent) in the control group were diagnosed with ovarian cancer.
"For women who have this condition and are at an extremely high risk for two gynecological cancers, this study provides a positive finding. We now have definitive evidence for doing something proactively that will prevent women with Lynch syndrome from ever getting either endometrial, or ovarian cancers, or even both," Lu says.
In the medical community, Lu says, there is little awareness of the link between endometrial and colon cancers, despite there being equal risk of women with the condition to develop both diseases.
"This study is a very important reminder to physicians to pay particular attention to a woman's family history of colon, endometrial and ovarian cancers, with genetic counseling becoming of utmost importance. If women with Lynch syndrome are identified, there needs to be coordinated care between the gastrointestinal and obstetrics and gynecologic medical disciplines," Lu says.
Given that the average age of developing endometrial cancer was 46 among the women in the study, typically, women can wait until after child-bearing years to have the surgery, Lu says.
The study was funded, in part, by a grant from the National Cancer Institute. Other M. D. Anderson authors on the study include: Kathleen M. Schmeler, M.D.; Mark F. Munsell; Pamela T. Soliman, M.D.; Molly S. Daniels; Kristin G. White; Stephanie G. Boyd-Rogers; Charlotte Sun; Brian M. Slomovitz, M.D.; David M. Gershenson, M.D. Authors Henry T. Lynch, M.D. and Mary Beth Clark are from Creighton University; authors Lee-May Chen, M.D., Kathleen Y. Yang, M. D., Mary M. Rubin, Ph.D., and Peggy G. Conrad are from the University of California at San Francisco.
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