Worldwide study highlights wide variation in bowel cancer risk for people with Lynch syndrome

New research has emphasised the need for more effective methods to triage bowel cancer screening for people with Lynch Syndrome based on their individual risk.

While we already knew that carrying an inherited mutation in some mismatch repair (MMR) genes puts people with Lynch syndrome at greater risk of bowel cancer, the new research has uncovered large variation in risk between individuals who have mutations in the same gene.

Though the average risk of bowel cancer of people with Lynch syndrome is high, this new research has discovered some are at low risk (the same level of risk as the general population) and therefore wouldn’t need the recommended colonoscopy every year.

Those at the other end of the risk spectrum are almost certain to develop bowel cancer (over 90 per cent) and may even need prophylactic surgery to remove the bowel before cancer develops.

However, it is currently not possible to determine where on the risk spectrum an individual with Lynch syndrome is, so until future research determines how to do this, all carriers will continue to be recommended an annual colonoscopy according to Australian guidelines.

Published in Lancet Oncology, Professor Mark Jenkins and Associate Professor Aung Ko Win of the Centre for Epidemiology and Biostatistics led the research with other Centre members including Drs James Dowty and Jeanette Reece, Mr Grant Lee and Professor John Hopper, as part of the International Mismatch Repair Consortium. Approximately 200 investigators from 32 countries contributed data from 6,000 Lynch syndrome families to this research.

"Our research could have significant clinical implications for the 90,000 Australians who have Lynch syndrome, because once we know how to estimate personal risks, they could have tailored screening,” said Professor Mark Jenkins.

"Family data may provide some insight into personal risk, but other genetic factors might also be important. Also, numerous environmental factors such as weight, smoking, and regular aspirin, can help provide personalised bowel cancer risk,"

The large international study also highlighted bowel cancer risk variations between North America, Europe and Australiasia, with potential clinical relevance for individuals within the 15 included countries.

For example, there is some suggestion that bowel cancer risk for people with Lynch syndrome is lower for men aged 50 in Europe, and higher for men aged 50 in Australasia.

Professor Jenkins said that the findings highlight that risk factors for bowel cancer for people with Lynch syndrome could vary across countries.

"We will continue building on this country and continent specific data, looking to include Asia and South America."