J Intern Med. 2020 Sep 14. doi: 10.1111/joim.13171. Online ahead of print.
Colorectal cancer (CRC) is besides breast, prostate, lung and skin cancers the most common cancers worldwide, and CRC is suitable for screening. The incidence of CRC varies considerably in different parts of the world; in well-developed countries, the incidence is between 30 and 70 per 100 000 inhabitants. In less developed countries such as Sub-Saharan Africa, the incidence is 10-20/100 000. Women have a lower incidence of CRC, and usually they have a 1/3 lower incidence. Several studies have
shown that it is possible to decrease mortality in CRC with about 20%, and data from countries with screening indicate that mortality is decreasing. The method of choice is under debate but the most feasible method is to test for blood in faeces, and if blood is present, a colonoscopy is performed. Other methods are more advanced faecal analyses, testing for mutations from CRC cancer, sigmoidoscopy, CT colonoscopy or optical colonoscopy. Colonoscopy is in most countries not available in sufficient amount and has to be carried out with big accuracy; otherwise, lesions will be missed or lead to complications. Gender is an issue in CRC screening, women have about 20% fewer colorectal adenomas and CRCs but they also have more right-sided lesions, more difficult to detect with tests for faecal blood less blood in faeces which leads to that other strategies may have to be developed for women in order to have the same effect of screening. Colorectal cancer screening is important to introduce in all countries together with other preventive measures such as information to stop smoking, obesity, exercise and smoking in order to reduce one of the most dangerous cancers.