A study published in the New England Journal of Medicine, shows that bowel cancer screening with faecal occult blood testing reduces the risk of dying from bowel cancer, and this effect lasts as long as 30 years. However, such screening does not influence the all cause mortality, so screened patients won’t necessarily live longer.
The study is a long term follow-up to the Minnesota Colon Cancer Control Study, which began in 1975 and included 46,551 participants aged between 50 and 80 years. Participants were randomly assigned to be screened with faecal occult blood testing every year or two years or to a control group . Screening was carried out in two six year periods, and the patients were then followed over the next 30 years.
More than 7 in 10 people died during the study, and whether they had been screened made no difference to when they died. However, in the annual screening group the risk of death from colorectal cancer was 32% lower than in the control group, and in the biennial group it was 22% lower than in the controls.
The magnitude of the screening benefits was similar to what was originally reported after 13 years of the trial, indicating that the effects of faecal occult blood testing persisted even after screening had stopped.
Men between 60 and 69 benefited the most from screening. Women over 70 also had a significant benefit from annual screening, but little benefit was seen among women under 60.
No studies have directly compared colonoscopy and faecal occult blood testing, although randomised trials are ongoing. The UK bowel cancer screening programme offers a faecal occult blood test every two years to men and women aged over 60.
BMJ 2013; 347:f5773