Colorectal cancer: introduction

In Scotland, after prostate cancer and lung cancer, colorectal cancer is the third most commonly diagnosed cancer in men and the third most common in women after breast cancer, and lung cancer (this excludes non-melanoma skin cancer).  In 2020, 1,801 men and 1,508 women were diagnosed with colorectal cancer in Scotland. Relative survival has improved over recent decades, with 60.4% of patients now surviving to five years after diagnosis.

The main risk factors for colorectal cancer are: Diet (i.e. vegetables and fibre are probably protective while red meat and processed meats may increase risk), obesity, lack of physical activity, alcohol, genetic, and (probably) long-term smoking (SIGN 126).

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 are now decreasing.

Randomised controlled trials over the world shows that it is possible to reduce mortality from colorectal cancer by screening. A pilot study of a new type of test – the faecal immunochemical test (FIT) – was carried out in NHS Tayside and NHS Ayrshire and Arran. The pilot showed improved uptake and positive predictive value when compared to previously used faecal occult blood testing (FOBT). FIT was rolled out nationally in November 2017. The Scottish Bowel Screening Programme has been a national programme since December 2009.