Objective Population screening for colorectal cancer (CRC) was introduced to Wales in October 2008. The aim of this study was to evaluate the early impact of screening on CRC services.

Design Prospectively collected data from the Bowel Screening Wales (BSW) programme and the Welsh Bowel Cancer Audit (WBCA) were used to identify all screen-detected (SD) CRC diagnoses in Wales between April 2009 and March 2011. Data from the WBCA were used to calculate surgical outcomes.

Results 444 SD cancers were registered during the study period representing 11% of all CRC diagnoses. There was a 9.9% increase in CRC incidence following the introduction of the BSW. SD patients presented with earlier stage disease; SD Dukes’ A 35.1% vs 13.9% symptomatic patients (p<0.001) and SD Dukes’ D 7.4% vs 21.8% symptomatic, (p<0.001). There were more colonic cancers among the SD population (p<0.001). The resection rate for SD cancers was 89%, significantly higher than symptomatic cancers (67.7%; p<0.0001). There was variability in the use of polypectomy as a definitive procedure to treat CRC between units. Overall laparoscopic resection was used in 52% of cases but with considerable interunit variability (0–92%).

Conclusions The introduction of screening has increased the workload of the colorectal multidisciplinary teams in Wales. This has occurred through both an increase in case volume and the identification of more patients with early stage disease. There is considerable interunit variability in the use of techniques of local excision and rates of laparoscopic resection that need to be addressed.