A new BMJ Guideline on colorectal cancer screening, prepared by a panel including Dr Juliet Usher-Smith at the Primary Care Unit, is the first to avoid a blanket recommendation for colorectal cancer screening for all above a specific age.

Instead the guideline suggests a personalized and risk-based approach for people aged 50 to 79 with a life expectancy of more than 15 years and suggests that individuals should assess the evidence with their clinician before they decide whether or not to be screened. The first author, Dr Lise Helsingen, is currently visiting the Primary Care Unit. Here she summarises the guideline.

The guideline, which includes decision aids to facilitate shared decision making and covers practical issues, is a BMJ Rapid Recommendation – a collaborative project between The BMJ and the MAGIC Evidence Ecosystem Foundation that aims at accelerating new evidence into practice.

It was triggered by newly released data from three large sigmoidoscopy screening trials with follow-up over 15 years. The guideline panel consisted of gastroenterologists, lay persons with experience with bowel screening, general practitioners, a nurse and guideline methodologists. No panel member had financial conflicts related to screening.

In the guideline we recommend that the choice of whether to screen for bowel cancer or not should be based on individual values and preferences.

We suggest that individuals calculate their 15 year risk of developing bowel cancer using tools such as the QCancer risk calculator. This calculator estimates cancer risk based on factors such as smoking status, age, sex, ethnicity, BMI, family and medical history, and is easy to use. Within the population under consideration for this guideline, there are groups with different risks of developing colorectal cancer, ranging from less than 1% to more than 15% over 15 years. Most people, however, will be in the range from 1% to 7%. Hundreds of calculations have been made across the whole world since the publication of the new guideline, suggesting a potentially wide impact.

In the guideline we suggest that when the 15-year risk of colorectal cancer is 3% or higher, it might be a good idea to screen, and when the risk is lower the benefits may not outweigh the burdens. However, we emphasize shared decision making based on balanced information about absolute benefits, harms and burdens of screening. Further we suggests that for any individual it may be reasonable to screen or not to screen, depending on individual values and preferences. We do not recommend any one screening test over another.

When developing the guideline we took into consideration that there are still many uncertainties in terms of what is the most effective screening test and at what age and interval they should be used. There are also uncertainties in whether the effect of screening differs between men and women, and at what magnitude of effect the population would find that the benefits of screening outweigh the harms and burdens. We suggest this should be the focus of future research, and emphasize that future evidence may alter the recommendations.

The guideline is focused on the individual person who considers screening and does not make recommendations for healthcare systems. However, since many well-informed individuals will choose to forego screening, we suggest that discussion and information sharing on screening for colorectal cancer would be a better marker of care rather than uptake, which is currently used as a performance indicator by many healthcare systems.

In a linked editorial Philippe Autier at the International Prevention Research Institute (iPRI) welcomes the shift away from maximizing uptake of screening to an approach based on individual risk and informed choice.

Author

Dr Lise M. Helsingen, Clinical Effectiveness Research Group, Oslo University Hospital, was a member of the panel that produced the new BMJ clinical practice guideline on colorectal cancer screening. She wrote this blog while visiting the PCU in October 2019.

References

• Rapid Recommendation (BMJ): http://bmj.com/cgi/content/full/bmj.l5515
• Guideline in MAGICapp: https://app.magicapp.org/public/guideline/EQNVKj
• Multiple comparisons evidence summaries and decision aids: http://magicproject.org/190220dist

Find out more

Lucy Lloyd, Communications, Primary Care Unit