LOS ANGELES (FRONTLINE MEDICAL NEWS) – The detection rate of significant polyps was highest for the first postoperative surveillance colonoscopies performed at 1 year following curative resection for colorectal cancer, results from a single-center study demonstrated.

“There’s no consensus on when to perform the first surveillance colonoscopy post curative resection for colorectal cancer,” lead study author Dr. Noura Alhassan said at the annual meeting of the American Society of Colon and Rectal Surgeons. For example, the American Society of Colon and Rectal Surgeons and National Carcinoma Comprehensive Network guidelines recommend a colonoscopy at 1 year, while the Canadian Association of Gastroenterology recommends surveillance at 3 years postoperatively.

In an effort to determine the optimal timing of the first surveillance colonoscopy following curative colorectal carcinoma resection, Dr. Alhassan and her associates retrospectively reviewed the charts of all patients who underwent colorectal resection from 2007 to 2012 at Jewish General Hospital, a tertiary care center affiliated with McGill University, Montreal. The study included patients who had a complete preoperative colonoscopy, those who had a complete postoperative colonoscopy performed by one of the Jewish General Hospital colorectal surgeons, and those who had colorectal cancer resection with curative intent. Excluded from the study were patients with stage IV colorectal cancer, those with a prior history of colorectal cancer, those who underwent total abdominal colectomies or proctocolectomies, those who underwent local excision, and those with familial cancer syndromes and inflammatory bowel disease.

Dr. Alhassan, a fourth-year resident in the division of general surgery at McGill University, said that the researchers classified the colonoscopic findings as normal, nonsignificant polyps, significant polyps, and recurrence. Significant polyps consisted of adenomas 1 cm or greater in size, villous or tubulovillous adenoma, adenoma with high-grade dysplasia, three or more adenomas, or sessile serrated polyps at least 1 cm in size or with dysplasia. Of the 857 colorectal resections performed during the study period, 181 met inclusion criteria. The tumor stage was evenly distributed among study participants and 57% of the resections were colon operations, while the remaining 43% were proctectomies.

The preoperative colonoscopy was done by one of the Jewish General Hospital gastroenterologists 43% of the time, by one of the Jewish General Hospital colorectal surgeons 41% of the time, and by an outside hospital 16% of the time. The median time to postoperative colonoscopy was 421 days (1.1 years). Specifically, 25.90% of patients underwent their first surveillance colonoscopy in the first postoperative year, 48.10% in the second year, 14.40% in the third year, 8.5% in the fourth year, and 2.7% in the fifth year.

Dr. Alhassan reported that the all-polyp detection rate was 30.1%; 21.3% were detected in postoperative year 1, 33.3% in year 2, and 34.6% in year 3.

The overall significant polyp detection rate was 10.5%, but the detection rate was 12.8% in postoperative year 1, 8% in postoperative year 2, and 7.7% in postoperative year 3. There were two anastomotic recurrences: one in year 1 (2.1%) and one in year 3 (3.8%).

On univariate analysis, factors associated with significant polyp detection were male gender, poor bowel preparation on preoperative colonoscopy, and concomitant use of metformin, while having stage III disease was associated with a lower significant polyp detection rate.

On multivariate analysis only male gender was associated with a higher significant polyp detection rate, while stage III disease was associated with a lower significant polyp detection rate.

“Significant polyp detection rate of 12.8% at postoperative year 1 justifies surveillance colonoscopy at 1 year post curative colon cancer resection,” Dr. Alhassan concluded. She reported having no financial disclosures.