Depending on their age, women diagnosed with uterine cancer may have a higher risk of developing colon cancer later on, according to a new study from Canada.
"As the survival has increased among cancer survivors, it's important to know what the other problems they're facing," said Dr. Harminder Singh, the study's lead author from the University of Manitoba in Winnipeg.
Cancer of the endometrium - the lining of the uterus - is the most common cancer
of the female reproductive tract. The American Cancer Society
estimates about 50,000 women will be diagnosed with the cancer in 2013 and about 8,000 will die from it.
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Previous research looking at women's risk for colon cancer following endometrial cancer produced mixed results. Also, no study looked at where in the colon those cancers showed up, which can help pick screening techniques.
For the new study, published in the Journal of Clinical Oncology, the researchers used data on 3,115 women diagnosed with endometrial cancer between 1987 and 2008 in the Canadian province of Manitoba.
The researchers then compared those participants to 15,084 women who were never diagnosed with cancer.
Using the women's medical records, the researchers then saw how many were diagnosed with colon cancer by 2009.
Overall, about 1.9 percent of women with endometrial cancer went on to get colorectal cancer. That compared to 1.6 percent of women who never had endometrial cancer.
While that's a small increase among women who already had cancer, it could have been due to chance, according to the researchers.
They did find, however, that seven women diagnosed with endometrial cancer before age 50 ended up with colon cancer during the study. Although a very small number, it works out to be about a four-fold increase over those who never had cancer.
The researchers also found those women and women diagnosed with endometrial cancer between age 50 and 65 years old were more likely to have cancer on the right side of their colons.
That finding, says Singh, suggests colonoscopy would be the preferred screening method in those women.
Dr. Noah Kauff, from the Memorial Sloan-Kettering Cancer Center in New York, told Reuters Health that the findings are consistent with previous research, but the increased risk may be - at least partially - due to women with a hereditary condition known as Lynch Syndrome.
Lynch Syndrome, according to Kauff, who was not involved in the new study, affects between one in 800 or 1,000 people and is known to put people at a higher risk for a number of cancers.
The new study's researchers didn't have data on how many women in their study had Lynch Syndrome, and can't rule out the possibility that it explains the increase.
Another possible explanation, said Singh, is that estrogen affects the risk for both endometrial and colon cancers.
Singh and his colleagues suggest women diagnosed with endometrial cancer should consider getting a colonoscopy and being screened for Lynch Syndrome - especially younger women.
The National Comprehensive Cancer Network, which represents leading cancer treatment centers, suggests people with Lynch Syndrome get a colonoscopy every one to two years starting between ages 20 and 25 years old.
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