Lynch syndrome: should I take aspirin to reduce my chance of getting bowel cancer?
Patient decision aid

What is the option?
Having Lynch syndrome means you are more likely to get certain cancers, including bowel cancer. Taking aspirin every day can help reduce your chance of getting bowel cancer. There are pros and cons to taking aspirin. This decision aid can help you and your healthcare team decide together if taking aspirin is right for you. It’s important to talk to your GP or specialist care team if you are thinking about taking aspirin, because it’s not suitable for everyone.

How likely am I to benefit?
If you take aspirin you are less likely to get bowel cancer, although some people will get bowel cancer even if they take aspirin . Results of a study in people with Lynch syndrome.looked at the effect that taking aspirin for 2 to 4 years had on the chance of getting bowel cancer, compared with taking a dummy tablet. The protective effect wasn’t seen straightaway, but it continued for many years after people stopped taking aspirin.

Regular colonoscopies, to spot cancers early if they develop, are recommended for people with Lynch syndrome whether they take aspirin or not. Your specialist team will tell you what other things you can do to reduce your risk of bowel and other cancers.
It is not possible to know in advance what will happen to any one person.

What are the possible side effects of aspirin?
The most common side effects include indigestion, bruising more easily and cuts taking longer to stop bleeding. Between 1 and 10 people in every 100 get these side effects (so 90 to 99 people in 100 do not ). Less commonly, aspirin can cause ulcers in the stomach and small bowel, but there are no reliable figures on how often this happens.
More rarely, aspirin can cause major bleeding in the gut: between 1 and 10 people in 10,000 get this (so 9,990 to 9,999 people in 10,000 do not). Aspirin can also make
a type of stroke known as haemorrhagic stroke (bleeding inside the brain) worse if it happens. Other rare side effects have also been reported occasionally. There is more information about these in the leaflet that comes with the medicine.

Other things to think about
• Aspirin is most likely to make a difference to your chance of getting bowel cancer if you take it every day for at least 2 years.
• The older you are, the more likely you are to get side effects.
• Aspirin may not be suitable for you if you have certain other conditions, for example if you have stomach ulcers or bleeding problems now or have had them in the past, or if you have had allergic-type reactions to similar medicines.

• For pregnant women:
– There is no good evidence that aspirin causes harm to the baby in early
pregnancy when taken at lower doses, or at higher doses taken short term.
– There is not much evidence about taking aspirin at higher doses long term in
pregnancy.
– Talk to your healthcare team before taking aspirin after 30 weeks of pregnancy.
• Aspirin is not recommended if you are breastfeeding.

• Aspirin has not been shown to reduce the chance of getting other cancers linked to Lynch syndrome.

There are still some things that are not known about taking aspirin to reduce the chance of bowel cancer if you have Lynch syndrome:
• It is not known how long aspirin should be taken for (in the study described, people took aspirin for 2 to 4 years). There is some evidence that the benefits increase the more years you take aspirin.
• The possible harms from taking higher doses of aspirin for many years are not certain.
• The best dose of aspirin to take is not known:

– A study comparing different doses is going on at the moment, but it will be
several years before the results are known.
– In the study described people took 600 mg aspirin per day. This is
much higher than the dose of aspirin used long term in other conditions.
– The higher the dose, the more likely you are to get side effects.
But a lower dose
might not work so well at reducing the chance of bowel cancer.
Talk to your healthcare team about the best dose for you.

UK National Guidance August 2020.