['Patients treated with surgery for colorectal cancer (CRC) should undergo colonoscopy examinations 1, 4, and 9 years later, to check for cancer recurrence. We investigated the use patterns of surveillance colonoscopies among Medicare patients.', 'We used the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database to identify patients who underwent curative surgery for colorectal cancer from 1992 to 2005 and analyzed the timing of the first 3 colonoscopies after surgery. Early surveillance colonoscopy was defined as a colonoscopy, for no reason other than surveillance, within 3 months to 2 years after a colonoscopy examination with normal results.', "Approximately 32.1% and 27.3% of patients with normal results from their first and second colonoscopies, respectively, underwent subsequent surveillance colonoscopies within 2 years (earlier than recommended). Of patients who were older than 80 years at their first colonoscopy, 23.6% underwent a repeat procedure within 2 years for no clear indication. In multivariable analysis, early surveillance colonoscopy was not associated with sex, race, or patients' level of education. There was significant regional variation in early surveillance colonoscopies among the Surveillance, Epidemiology, and End Results regions. There was a significant trend toward reduced occurrence of second early surveillance colonoscopies."] Do many patients who undergo surgery for colorectal cancer receive surveillance colonoscopies earlier than recommended by guidelines?