Screening for colorectal cancer: what is the impact on the determinants of outcome?

Colorectal cancer screening has been introduced across the UK following several large randomised control trials and a Cochrane review that have shown a reduction in cancer specific mortality with population based Faecal Occult Blood testing. This has been attributed to the detection of more early stage disease. It is well known that in addition to stage at presentation there are a variety of other key factors that determine a patient's outcome following a diagnosis of colorectal cancer. For example there are tumour-related factors, such the presence of venous invasion and tumour necrosis, and also host-related factors, both in terms of demographic profile and an elevated circulating host inflammatory response that have been shown to be predictive of a poorer outcome. The present review summarises both the background behind the current screening programme and the observed and anticipated impact that colorectal cancer screening will have on the key determinants of outcome.