A new study by Japanese researchers has found that over half of colon cancers in the elderly may be missed if sigmoidoscopy is used for screening in place of colonoscopy.
The explanation lies in the fact that the frequency of right-sided colon cancer increases with patient age, and the sigmoidoscope does not reach the right side of the colon.
The researchers said that in 191 patients who were found by colonoscopies to have colon cancer, the proportion with right-sided colon cancer rose steadily from a low 15 percent of those under 50 years of age to a high of 57 percent for those over age 80.
"Over half of colon carcinomas may be missed if sigmoidoscopy alone is used for screening," the researchers reported in Gastrointestinal Endoscopy. "The frequency of right-sided colon cancer increases with patient age. Hence, colonoscopy may be indicated in the elderly for colorectal cancer screening."
