Can Lynch syndrome cause bowel cancer?

Having Lynch syndrome does not mean bowel cancer is inevitable. It means risk is higher than usual, so planned bowel surveillance and attention to persistent symptoms are particularly relevant.

Lynch syndrome is caused by an inherited change affecting the system that corrects copying errors in DNA. When this mismatch repair system does not work properly, errors can build up as cells divide and may eventually allow a bowel tumour to develop.

A genetic result can clarify which inherited change is present. Testing a bowel tumour may also reveal features associated with faulty mismatch repair, although tumour findings and inherited genetic testing answer different questions.

A genetics or specialist bowel team can create a surveillance plan based on the gene involved, personal history, previous polyps, and cancers in close relatives. Colonoscopy allows the bowel lining to be inspected and suspicious growths to be removed or sampled.

Keep a copy of the genetic report and share it with relevant clinicians. Biological relatives may be offered genetic counselling so they can make an informed choice about testing for the specific family variant.

Arrange a medical assessment for blood in the stool, a persistent change in bowel habit, unexplained weight loss, ongoing abdominal pain, or unusual tiredness. These symptoms have several possible causes, but they should not be ignored in someone with Lynch syndrome.

Seek urgent help for heavy rectal bleeding, fainting, severe or escalating abdominal pain, repeated vomiting, or a swollen abdomen with inability to pass stool or wind. Urgency comes from the symptom itself, not from whether cancer is thought to be likely.

Ask which gene variant was found, when your next colonoscopy is due, what bowel preparation involves, which symptoms should bring the appointment forward, and how relatives can access genetic counselling.