The world's largest clinical trial to examine whether aspirin can prevent cancers returning has begun in the UK.
Researchers will compare groups of patients taking different doses of aspirin with people taking dummy (placebo) pills and check for any recurrences of cancer.
Speaking personally, if I was recovering from cancer and taking part in an experiment to determine whether aspirin would help me, I would read about aspirin and cancer. For example I would search Google and surely discover results such as this. Daily aspirin 'prevents and possibly treats cancer'
This would tempt me to take some aspirin on the side, in addition to the experimental substance—just as a precaution.
How is this different from other such studies? Well there is a big difference—normally these double-blind experiments are carried out with a new drug so
(a) No-one knows whether it will work. It might even have detrimental effects.
(b) It isn't available to the general public. You either get the drug or you don't. There is nowhere you can get your own supplies.
Some of the Problems
Unlike with new, experimental drugs: anyone, literally anyone, can buy aspirin in any quantity they want.
The temptation to cheat will be enormous—it's a matter of life and death.
If people cheat they may use wildly different amounts of the substance and therefore throw the results into chaos.
People who are actually receiving aspirin don't know that they are because it is a blind test. They are just as likely to cheat. A simple blood test will only detect cheaters who are on the placebo.
How can cheaters be 'disciplined'? Can the intermediate results over the 5 years of the test be suppressed in such a way as to prevent defectors?
Is this study doomed from the start?
What can the experimenters do to prevent the problems I have outlined?