Sessile serrated adenomas (SSAs) are known to be precursors of colorectal cancer (CRC). The proper interval of follow-up colonoscopy for SSAs is still being debated. We sought to determine the proper interval of colonoscopy surveillance in patients diagnosed with SSAs in South Korea.

We retrospectively reviewed the medical records of patients diagnosed with SSAs who received 1 or more follow-up colonoscopies. The information reviewed included patient baseline characteristics, SSA characteristics, and colonoscopy information.

From January 2007 to December 2011, 152 SSAs and 8 synchronous adenocarcinomas were identified in 138 patients. The mean age of the patients was 62.2 years and 60.1% patients were men. SSAs were located in the right colon (i.e., from the cecum to the hepatic flexure) in 68.4% patients. At the first follow-up, 27 SSAs were identified in 138 patients (right colon, 66.7%). At the second follow-up, 6 SSAs were identified in 65 patients (right colon, 66.7%). At the 3rd and 4th follow-up, 21 and 11 patients underwent colonoscopy, respectively, and no SSAs were detected. The total mean follow-up duration was 33.9 months. The mean size of SSAs was 8.1±5.0 mm. SSAs were most commonly found in the right colon (126/185, 68.1%). During annual follow-up colonoscopy surveillance, no cancer was detected.

Annual colonoscopy surveillance is not necessary for identifying new CRCs in all patients diagnosed with SSAs. In addition, the right colon should be examined more carefully because SSAs occur more frequently in the right colon during initial and follow-up colonoscopies.