Abstract: No RCTs were identified. Five observational studies (N = 7199) met the inclusion criteria. The studies scored well on the Newcastle-Ottawa scale, but due to the nature of observational studies, a high risk of bias was assigned to all the studies. Three studies were pooled to assess the rate of cancer detected in the surveillance group compared to the non-surveillance group. The studies found a significantly higher rate of cancer detection in the non surveillance group compared to the surveillance group. CRC was detected in 1.83% (53/2895) of patients in the surveillance group compared to 3.17% (135/4256) of patients in the non-surveillance group (OR 0.58, 95% CI 0.42 to 0.80; P = 0.0009). Four studies were pooled to assess the death rate associated with CRC in patients who underwent surveillance compared to patients who did not undergo surveillance. There was a significantly lower death rate associated with CRC in the surveillance group compared to the non-surveillance group. Eight per cent (15/176) of patients in the surveillance group died from CRC compared to 22% (79/354) of patients in the non-surveillance group (OR 0.36, 95% CI 0.19 to 0.69, P=0.002). Data were pooled from two studies to examine the rate of early stage versus late stage colorectal cancer (Duke stages A & B compared to Duke stages C & D) in patients who underwent surveillance compared to patients who do not undergo surveillance. A significantly higher rate of early stage CRC (Duke A & B) was detected in the surveillance group compared to the non-surveillance group. Sixteen per cent (17/110) of patients in the surveillance group had early stage CRC compared to 8% (9/117) of patients in the non-surveillance group (OR 5.40, 95% CI 1.51 to 19.30; P = 0.009). A higher rate of late stage CRC (Duke C & D) was observed in the non-surveillance group compared to the surveillance group. Nine per cent (10/110) of patients in the surveillance group had late stage CRC compared to 16% (19/117) of patients in the non-surveillance group (OR 0.46, 95% CI 0.08 to 2.51; P = 0.37). A GRADE analysis indicated that the quality of the data was very low for all of these outcomes. The included studies did not report on the other pre-specified outcomes including time to cancer detection, time to death and adverse events. The current data suggest that colonoscopic surveillance in IBD may reduce the development of both CRC and the rate of CRC-associated death through early detection, although the quality of the evidence is very low. The detection of earlier stage CRC in the surveillance group may explain some of the survival benefit observed. RCTs assessing the efficacy of endoscopic surveillance in people with IBD are unlikely to be undertaken due to ethical considerations.

Plain-language summary: Five observational studies with 7199 patients were used to compare endoscopic surveillance to non-surveillance. The key findings of the review were that a higher rate of cancer occurred in the non-surveillance group compared to the surveillance group, and that a lower rate of colon cancer-associated death was demonstrated in the surveillance group compared to the non-surveillance group. In patients undergoing surveillance, the odds of colon cancer development were reduced by 42% and the odds of death associated with colon cancer was reduced by 64%. Surveillance resulted in detection of a higher rate of early stage colorectal cancer in the surveillance group compared to the non surveillance group which may explain the improved survival seen with surveillance. The overall quality of the evidence is very low due to the nature of observation studies and the low number of events. Nonetheless, these results suggest that endoscopic surveillance in people with IBD may reduce the development of colon cancer through early detection and may also reduce the chances of dying from colon cancer.