A study of nearly 56,000 people screened for colorectal cancer with sigmoidoscopy has found that if the scope is not inserted far enough into the colon, the risk of subsequent colorectal cancer in the last part of the colon was tripled. Women and the elderly over 80 were more likely to experience inadequate scopes.
Researchers reviewed the records of 55,791 people sreened with sigmoidoscopy as part of the Kaiser Permanente of Northern California Colon Cancer Prevention (CoCaP). Women were more than two times likely to have the sigmoidoscope withdrawn prematurely, the elderly more than two and a half times.
When the scope did not reach 40 centimeters, risk for distal (lower end) colorectal cancer increased three times. Between 40 and 59 centimeters, risk increased less but still significantly.
In those cases where sigmoidoscopy cannot be completed fully, the research team recommended an alternative screening method such as colonoscopy or barium enema.
Dr. V. Paul Doria-Rose reported results of the research team at the [Fred Hutchinson Cancer Research Center](http://www.fhcrc.org/) in Seattle in the September, 2005 edition of [*Gut*](http://gut.bmjjournals.com/)
Dr. Doria-Rose wrote:
Older individuals and women are at an increased risk of having inadequate sigmoidoscopy. Because inadequate sigmoidoscopy results in an increased risk of subsequent CRC, physicians should consider steps to maximise the depth of insertion of the sigmoidoscope or, failing this, should consider an alternative screening test.
[Read the study abstract in *Gut*.](http://gut.bmjjournals.com/cgi/content/abstract/54/9/1273)
[Read a Reuters Health article about the study on *Medscape.*](http://www.medscape.com/viewarticle/511657)