Results from the largest trial with the longest follow up of the effects of once-only flexible sigmoidoscopy (flex-sig) screening show that a single screening test can reduce the chance of developing colorectal cancer by 24% and the chance of dying from colorectal cancer by 25%, for up to 21yrs after screening.
The trial recruited over 170,000 men and women aged 55-64 from 506 general practices serving 14 UK hospitals between 1994-99. After 21 years, there were 47 fewer cases and 16 fewer colorectal cancer deaths per 100,000 person-years in the group invited to screening than in the control group. Effects were particularly evident in the distal colorectum, with 196 v 708 deaths in the screening group compared with controls.
Colorectal cancer is the fourth most common cancer and the second most common cause of cancer deaths each year in the UK. It is already well documented that screening in individuals without symptoms can lower the chance of dying from colorectal cancer, and can help to prevent it developing in the first place, but this is the first trial to show such a long-lasting effect.
Authors say that their results provide important data to inform colorectal cancer screening guidelines. Co-author Stephen Duffy said: These results show substantial long term reductions in colorectal cancer incidence and mortality with a single flexible sigmoidoscopy examination. Flexible sigmoidoscopy has great potential as one of the items in the toolbox for prevention and control of colorectal cancer, and it is underutilised worldwide.
This trial was carried out by researchers at Imperial College London and Queen Mary University London, and funded by the National Institute of Health and Care Research and Cancer Research UK.
Long-term effects of once-only flexible sigmoidoscopy screening on colorectal cancer incidence and mortality: 21-year follow-up of the UK Flexible Sigmoidoscopy Screening randomised controlled trial. Kate Wooldrage, Emma C Robbins, Stephen W Duffy, Amanda J Cross. Lancet Gastroenterol Hepatol 2024; July 19, 2024 https://doi.org/10.1016/ S2468-1253(24)00190-0