CaPPtain's Blog: John Burn, June 2020

posted on Tuesday, 16th June 2020

Not tagged.

Well, we finally got there.  The 10-year follow up paper on the CAPP2 study is now published in the Lancet (13th June 2020)*.  It may seem a long time since the 2011 CAPP2 paper but we wanted to extend the analysis to include the second decade for those who started earliest. Our aim was to see if the protective effect seen in our 2011 analysis persisted for more than the average of 5 years since starting in the trial.

The important take home message is that the effect was even clearer than in 2011, the protective effect of aspirin against colorectal cancer has persisted in this long-term follow up, for up to 20 years.  The gold standard test in any randomised trial is to demonstrate a significant difference on "Intention to Treat".  This means that everyone who started in the aspirin part of the trial is included, whether or not they stuck with the treatment.  This is a very hard test and the result did not reach the necessary levels of statistical significance last time in 2011, but this time it did, providing convincing evidence that the effect is due to an overall cancer preventative property of aspirin.

When asking how big the difference was, known as "efficacy", it still is sensible to look at all the cancers in the LS folk who took the treatment for the planned two years at least.  We judged this as people who had taken a total of 1400 trial tablets over that time period.  The statistical analysis of this group showed there were half as many colon cancers in those who took aspirin regularly during the trial.  Obviously, many may have taken aspirin in the subsequent years after completing the CAPP2 trial but this might apply to all the participants.  The only difference between the two groups was the couple of years on the trial when one group had real aspirin tablets and the other had placebo tablets.

For those of you who like the real numbers, here they are:  427 people took aspirin and 40 of them got colon cancer.  Two of them got colon cancer twice, so there were 42 bowel cancers over an average of 10 years follow up.  434 people were in the placebo group and 58 of them got colon cancer, some more than once making a total of 71 bowel cancers, that's 29 more than the aspirin group.  

The UK National Institute for Healthcare and Clinical Excellence (NICE) announced in January 2020, based on the evidence from the 2011 CAPP2 paper, that aspirin should be recommended to all adults with Lynch syndrome.  NICE noted that the CaPP3 study would provide information on the optimal dose but in the meantime supported a lower dose.  We are recommending 150mg daily for people of average size, less if you are of small build and more if you are heavier.  This is based on the recent work of Peter Rothwell reanalysing the old trial data and, on our paper, looking at the higher cancer risk in LS people who were overweight.   The Australian authorities have now endorsed use of aspirin in LS and our European survey organised by the European Hereditary Tumour Group has just been accepted for publication and shows general professional support.  It is still a recommendation and we need to get cancer prevention listed for aspirin in the British National Formulary.

The other big news is, of course, theCovid-19 pandemic.  We are aware that some participants in CaPP3 stopped their aspirin after newspaper reports that non-steroidal anti-inflammatory drugs might make the illness worse.  We now know this is not true.  In fact, a couple of Covid-19 trials have now started including aspirin as a treatment because it has been shown that excessive clotting is part of the illness.  We are planning an aspirin trial in early Covid-19 cases in Newcastle too.  The take home message is thatIT'S OK TO TAKE ASPIRIN!  People in CaPP3 can return to their prescribed aspirin.  As follow up appointments are arranged, we will need to know who stopped taking their aspirin and for how long, so we can include this in the final CaPP3 analysis in 2024.

If you have Lynch syndrome and are not on the trial, then this blog and the CAPP2 Lancet paper will support discussions with your doctor to discuss regularly taking aspirin.  Make sure your blood pressure is normal and that you don't have a treatable Helicobacter pylori infection in your stomach, as many people still do.  If clear, then take some aspirin to reduce your colon cancer risk.

Thanks again to all the people who are taking part in CaPP3. And a special thank you to the CaPP3 participants who have completed the five years of study aspirin. You will be receiving a personal thank you letter from the study (once approved by the ethics committee). The CaPP3 study will keep in contact with you annually after your Year 5 contact. As we have shown in CAPP2, your participation in these trials is essential if we are to change clinical practice. We still need to know the best dose, so if you are in CaPP3, please keep taking the study aspirin.

John Burn
16th June 2020

*Additional links

https://www.ncl.ac.uk/press/articles/latest/2020/06/10yearaspirinstudy/

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30973-9/fulltext#.XuOQnsE_khU.twitter

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