Does the location of colorectal carcinoma differ between screened and unscreened populations?

Screening for colorectal malignancy using faecal occult blood testing is established across the UK. In NHS Grampian the programme was introduced in 2007. Previous studies have reported no difference in anatomical locations of cancers detected by screening programmes compared with those in unscreened populations. This study aims to review the location of tumours detected in an established screening programme compared with those diagnosed through symptomatic presentation within the same population.

All patients discussed at the regional multidisciplinary meeting between June 2007 and August 2011 were included. Data were collated prospectively from multidisciplinary team records while site of tumour was documented from radiology, endoscopy, operative and pathology reports. Comparative statistics (χ(2) ) were performed using spss 19.

Of 1487 patients included 255 were detected via the screening programme and 1232 from symptomatic presentation. More left sided tumours (splenic flexure to rectosigmoid) were detected via screening (P=0.005). Of non-screened patients (n=1232), 456 (37%) tumours were right sided (caecum to distal transverse colon), 419 (34%) were left sided and 357 (29%) were in the rectum. This compares with the screened group (n=255): right sided 74 (29%), left sided 113 (44%) and rectal 68 (27%).

More left sided tumours appear to be detected in screened patients compared with symptomatic presentation, contrary to previously published work. These results may be worthy of further consideration given the ongoing debate on the optimal means of screening.