Is simpler colon screen enough for many women?

Women younger than 70 have a relatively low risk of abnormal growths in the upper part of the colon, a new study confirms - suggesting, researchers say, that many women can opt for less invasive colon cancer screening.

Most experts recommend that people at average risk of colon cancer start having screening tests for the disease at age 50. And there are choices.

The U.S. Preventive Services Task Force, a government-backed body that sets screening guidelines, recommends three options: a yearly stool test that looks for hidden blood; sigmoidoscopy every five years, along with stool testing every three years; or colonoscopy every 10 years.

Other groups, like the American Cancer Society, have similar recommendations.

The reality, though, is that colonoscopy - the most extensive, invasive and expensive of the tests - has become the screening method of choice in the U.S.

"But it shouldn't be one strategy for everyone," said Dr. Thomas F. Imperiale, a gastroenterologist at Indiana University in Indianapolis who led the new study.

One reason, he said, is because colonoscopies deter some people from getting any screening. "There are a lot of people who stay away from colon cancer screening altogether because they equate screening with colonoscopy," Imperiale said. "But there are alternatives."

For their study, Imperiale and his colleagues looked at data on more than 10,000 U.S. adults age 50 and up who underwent a screening colonoscopy. They found that among women younger than 70, only one percent had either a tumor or advanced polyp - a growth that could become cancer - in the upper part of the colon.

That was half the rate seen among men their age. Older adults had the highest risk: nine percent of men and four percent of women older than 70 had a tumor or advanced polyp in the upper colon.

According to Imperiale, the findings suggest that for women younger than 70, sigmoidoscopy could be adequate as an initial colon cancer screening.

Like colonoscopy, sigmoidoscopy uses a long flexible tube equipped with a tiny video camera to see the interior of the colon. The difference is that a colonoscopy gives images of the entire colon, while a sigmoidoscopy looks only at the rectum and lower portion of the colon.

So a sigmoidoscopy can be done relatively quickly - in about 15 minutes - without sedation, and with a lower risk of perforating the colon. It can also be done by primary care doctors or trained nurse practitioners; colonoscopies are usually done by gastroenterologists.

"All we're saying is, with people at average risk of colon cancer, there are some groups who may not need a colonoscopy," Imperiale said.

He and his colleagues report the findings in the American Journal of Medicine.