Routine testing for bowel cancer should not be recommended for everyone aged 50-79 years because, for those at very low risk, the benefit is small and uncertain and there are potential harms, says a panel of international experts.
But they say screening should be recommended for men and women with a risk of 3% or more in the next 15 years, as this is the point at which the balance of benefits and harms tilts in favour of screening.
Colorectal cancer is a common type of cancer – about 1 in 20 people in most high income countries will get it during their lifetime. A person’s risk depends on their age, sex, genetics and lifestyle factors, such as alcohol intake, smoking, physical activity and diet.
Most guidelines recommend screening for everyone from age 50, irrespective of their individual risk. At this age, the risk of developing bowel cancer over the next 15 years is typically 1–2%, meaning that in a group of 100 people with the same risk factors, one or two will develop bowel cancer within the next 15 years.
The researchers’ recommendations apply to healthy individuals aged 50-79 years with a life expectancy of at least 15 years, following risk assessment using the QCancer calculator, available at https://www.qcancer.org/female for women, and https://qcancer.org/male/ for men.
For men and women with an estimated 15-year bowel cancer risk below 3%, they suggest no screening. However, for men and women with an estimated 15-year bowel cancer risk above 3%, they suggest screening, and say most informed individuals in this group are likely to choose screening after discussing the potential benefits and harms with their doctor.
The most common screening option is home faecal testing (FIT) every year or every two years.
Helsingen LM, et al. BMJ 2019;367:l5515