Evidence from multiple large studies convincingly shows that colorectal cancer screening prevents colorectal cancer and reduces mortality from it. The benefit lies primarily in actual participation: invitation alone has less effect than expected (NordICC study). The effect on overall life expectancy is modest, but the protection against colorectal cancer specifically is clearly demonstrated.
Of all the cancer screenings that exist, bowel cancer screening is one of the most well-supported. The stool test (FIT) is completely risk-free and can be done at home. A colonoscopy is more invasive: the chance of a complication such as bleeding or perforation is small but real, and it is good to know that before you decide.
The evidence that screening prevents bowel cancer and reduces mortality from it is convincing, and is based on multiple large studies. A recent large study (NordICC) showed that people who actually underwent a colonoscopy developed bowel cancer at a clearly lower rate. It did emerge, however, that the invitation alone -- regardless of whether people actually came in -- had less effect than expected, which underlines that the benefit lies in actually participating. The impact on your overall life expectancy is more modest than you might hope: on average, the number of life-years gained over a lifetime is small, although that carries less weight if your specific goal is to prevent bowel cancer.
In the Netherlands there is a free population screening programme for people aged 55 to 75: you automatically receive a FIT test kit. If an abnormal result comes back, a colonoscopy follows. Outside that age group, or if you want to start earlier, your GP is the right point of contact.
Strong evidence, based on 3 source(s), including controlled or causal research.