Colorectal cancer: introduction

In Scotland, after non-melanoma skin cancer, lung cancer, and prostate cancer, colorectal cancer is the fourth most commonly diagnosed cancer in men, and the fourth most common in women after non-melanoma skin cancer, breast cancer, and lung cancer.  Currently, around 1890 men and 1590 women are diagnosed with colorectal cancer in Scotland every year.  It is the second most common cause of death from cancer in men after lung cancer, and the third most common in women after lung and breast cancer.  Survival has improved over recent decades, with around 50% of patients now surviving to five years after diagnosis.

The main risk factors for colorectal cancer are genetic factors, dietary factors (vegetables and fibre are probably protective, red meat may increase risk), obesity, lack of physical activity, and (probably) long-term smoking (SIGN67, 2003).

Incidence rates of colorectal cancer increased in Scotland between the mid-1970s and the mid-late 1990s (Gray et al, 2002), but more recent data suggest that incidence rates have reached a plateau in males, and may even be starting to decrease in females.

It is expected that the incidence of colorectal cancer will increase up to the period 2016-20, partly due to ageing of the population (Scottish Executive, 2004). 

Randomized controlled trials carried out in Minnesota, USA, Funen, Denmark, and Nottingham, UK have shown that it is possible to reduce mortality from colorectal cancer by screening based on faecal occult blood testing (FOBT). Pilot studies carried out in Grampian, Tayside, and Fife, and in parts of West Midlands have demonstrated that screening with FOBT is feasible in the UK, and that it should reduce deaths from colorectal cancer.  It is anticipated that the Scottish Bowel Screening Programme will rollout to the rest of Scotland from 2007 onwards.