Screen-detected colorectal cancers are associated with an improved outcome compared with stage-matched interval cancers

Abstract

Background:Colorectal cancers (CRCs) detected through the NHS Bowel Cancer Screening Programme (BCSP) have been shown to have a more favourable outcome compared to non-screen-detected cancers. The aim was to identify whether this was solely due to the earlier stage shift of these cancers, or whether other factors were involved.Methods:A combination of a regional CRC registry (Northern Colorectal Cancer Audit Group) and the BCSP database were used to identify screen-detected and interval cancers (diagnosed after a negative faecal occult blood test, before the next screening round), diagnosed between April 2007 and March 2010, within the North East of England. For each Dukes' stage, patient demographics, tumour characteristics, and survival rates were compared between these two groups.Results:Overall, 322 screen-detected cancers were compared against 192 interval cancers. Screen-detected Dukes' C and D CRCs had a superior survival rate compared with interval cancers (P=0.014 and P=0.04, respectively). Cox proportional hazards regression showed that Dukes' stage, tumour location, and diagnostic group (HR 0.45, 95% CI 0.29–0.69, P<0.001 for screen-detected CRCs) were all found to have a significant impact on the survival of patients.Conclusions:The improved survival of screen-detected over interval cancers for stages C and D suggest that there may be a biological difference in the cancers in each group. Although lead-time bias may have a role, this may be related to a tumour's propensity to bleed and therefore may reflect detection through current screening tests.

Survival of patients with symptom- and screening-detected colorectal cancer

“…However, in agreement with our findings, Mapp et al found a significant survival advantage in patients with screen-detected cancers in the Nottingham FOBT trial which persisted after control for tumor stage [19]. In two studies (n=633 and 514, respectively) conducted in the context of the FOBT based British Bowel Cancer Screening Programme, survival advantages for screen-detected cancers over symptom-detected cancers were likewise observed even in stage-specific and stage-adjusted analyses [22, 24]. Similar results were recently reported for screening colonoscopy detected colon cancer in a single center study (n=1,071) from the US [25].…”

Screen‐detected and interval colorectal cancers in England: Associations with lifestyle and other factors in women in a large UK prospective cohort

“…8,9,[18][19][20] Our finding that smoking is related to risk of gFOBt interval, but not of screendetected, cancers is consistent with the emerging picture of molecular/morphological type-specific tumours which appear to behave differently both in terms of aetiology, and of screening. For FOB programmes, this may include tumours which either do not bleed sufficiently for detection, or whose location (more proximal, or rectal) or gross morphology mean that it is less likely either that faecal haemoglobin is present in a detectable form, or that the lesion is detected at diagnostic colonoscopy.…”

Appearances of screen-detected versus symptomatic colorectal cancers at CT colonography

“…Epidemiological series show that screen-detected cancers are typically of earlier stage than non-screen detected tumours [14] and have superior survival [15]. Similarly, cancers detected by screening CTC are generally of earlier histological stage than the population average [16].…”