A major trial is under way to determine the impact of single screening sigmoidoscopy on colorectal cancer incidence and mortality. Although the trial will take years to complete, outcomes from the recruitment and screening phases of the trial suggest that single screening sigmoidoscopy has a high cancer detection rate and is relatively safe and acceptable to patients. The findings appear in the December 4 issue of the Journal of the National Cancer Institute.
Scientists believe that colorectal cancers develop from adenomous polyps (abnormal growths) over a period of 10 to 15 years. Some have proposed that a single screening sigmoidoscopy around age 60 is a cost-effective approach to screening people for colorectal cancer. A sigmoidoscopy involves inserting a short, lighted tube into the rectum to check the colon wall for cancer and other abnormalities.
SCORE is a multicenter randomized controlled trial in Italy designed to measure the extent of reduction in colorectal cancer incidence and mortality achieved by a single screening sigmoidoscopy examination and to determine both the optimum age range for screening and how long the protective effect lasts.
Nereo Segnan, M.D., and his colleagues from the SCORE Working Group in Italy randomly assigned 34,292 people aged 55 to 64 to either an intervention group that was invited to undergo a sigmoidoscopy or a control group that was not invited for screening. Screenees who were found to have colorectal cancer or high risk polyps were referred for further testing with colonoscopy.
Of the people examined by sigmoidoscopy, 10.8% were found to have adenomas in the left side of the colon, the side closest to the rectum. Of the people who underwent further testing with colonoscopy, 15.5% were found to have adenomas in the right side of the colon. Colorectal cancers were found in 54 of the participants, a rate of 5.4 per 1,000. Furthermore, the procedures appeared relatively safe, with one perforation in nearly 10,000 sigmoidoscopy exams and one perforation in nearly 800 colonoscopies. There was also one hemorrhage requiring hospitalization after polypectomy (removal of a polyp). More than 80% of those screened described the associated pain as mild or less than expected.
“In conclusion, the baseline results from the SCORE trial show that sigmoidoscopy can be an acceptable and safe screening strategy for colorectal cancer,” the authors write. “The high yield of advanced lesions and early colorectal cancer is consistent with the projected substantial impact of sigmoidoscopy screening on colorectal cancer incidence and mortality.”