The incidence of colorectal cancer in patients with previously removed polyp(s)-a cross-sectional study.

Background: Years ago, it was established that removal of adenomas will lead to a lower incidence of colorectal cancer. This study aims to establish the occurrence of colorectal cancer in unselected patients after index colonoscopy with polyp removal.

Methods: A prospectively collected dataset on colonoscopy covering 25 consecutive years was used. Patients in who during the index (first) procedure a polyp(s) was removed were included. Excluded were patients with colorectal cancer and patients belonging to Lynch families. In case of cancer time after the index and previous procedure, tumor stage, histology of earlier removed polyps, localization of the tumor and demographics were noted.

Results: In 1,617 patients polyp(s) were removed. Thirty (1.9%) patients developed colorectal cancer. In 18 cases adenomas were removed during prior endoscopies. Five patients only had hyperplastic polyp(s). Nine patients with cancer already were older than 75 years when the previous endoscopy was done. Patients with adenomas prior to the cancer were older compared with patients with hyperplastic polyps [mean (SD): 71.6 (5.8) versus 64.2 (10.5) years, P=0.046]. The majority of cancers were located in the proximal colon (75%). The time between diagnosing cancer and the previous colonoscopy was mean 70.6 months with a median of 60.0 months (range, 12.0-167.0 months).

Conclusions: It is concluded that follow-up after removal of polyps in normal daily practice is associated with a low incidence of developing colorectal cancer.