Colon Cancer Condition Linked to Other Cancers

Gynecologic Surgeries Decrease Risk of Additional Disease

Women diagnosed with Lynch syndrome, a condition associated with colon cancer, are also at risk of developing endometrial and ovarian cancers, but the probability of developing the diseases can be eliminated with surgery to remove the uterus and ovaries, according to a new study.

The results, published by M. D. Anderson researchers, appeared in the Jan. 19 issue of The New England Journal of Medicine.

One key reason the researchers embarked on this study was that the majority of the Lynch syndrome research conducted during the last 20 years has been focused on colon cancer risk, says the study's lead author, Karen Lu, M.D., associate professor in M. D. Anderson's Department of Gynecologic Oncology. "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."

Statistics for condition show higher rate of cancers

Lynch syndrome, also called hereditary nonpolyposis colon cancer, is an inherited disorder in which affected individuals - men or women - have a much higher-than-normal chance of developing colon cancer and/or other types of cancer (including cancers of the endometrium or uterus, ovaries, stomach, small bowel and brain). The cancers usually develop before the age of 60. About one in every 1,000 individuals carries the gene mutation that causes Lynch syndrome, Lu says.

Lynch syndrome accounts for about:

• 3%-5% of all colon and endometrial cancers
• 2% of all ovarian cancers

Women with Lynch syndrome have a:

• 40%-60% risk of developing endometrial cancer
• 10%-12% risk of developing ovarian cancer

Women in the general population have a:

• 3% risk of developing endometrial cancer
• 1%-2% risk of developing ovarian cancer

More women developed cancer without surgery

In the study, Lu and her colleagues evaluated 315 women with Lynch syndrome. Out of this number, 254 women had not undergone surgery to remove the ovaries (oophorectomy) or uterus (hysterectomy). Sixty-one of the women who had surgery had undergone a hysterectomy, and 47 of the 61 also had their ovaries removed.

"In our study, none of the women who underwent surgery subsequently developed endometrial or ovarian cancer," Schmeler says.

Of the women who did not have surgery:

• 69 were diagnosed with endometrial cancer
• 12 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," Lu says. "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.

While the average age of developing endometrial cancer is 46 among women in the study, they can wait until after child-bearing years to have the surgery, Lu says.