In the second of the papers, the authors analyzed the effect of low dose aspirin on cancer metastasis (the spreading of cancer beyond its original site). The aspirin was also given in controlled trials to see whether it reduced the incidence of stroke; among those who were given aspirin and subsequently developed cancer, the chances of metastasis — a leading cause of death from cancer — was 36 percent lower than among those given a placebo and who subsequently developed cancer
In the last of the papers, the authors used a case control study to demonstrate that those who took low-dose aspirin (but not in controlled trials) were at lower risk of developing colorectal cancer than those who did not; aspirin also protected against the development of esophageal and stomach cancers.
Does this mean that those of us who have reached the age of cancer — the incidence of cancer rises with age — should all be taking low-dose aspirin prophylactically? There is no indubitably correct answer to this question, and it all depends on your scale of values. In the first trial, about 35,000 people had to take aspirin for five years in order that 100 cancer deaths were avoided. Would you take a pill daily for five years for a 1 in 350 chance of saving your life?
True, the tablet is a small one, but the papers did not set out to answer the question whether taking it daily for a long time resulted in any bad outcomes other than stroke and cancer. I, alas, shall not be taking it, though for purely personal and psychological reasons. I so detested the taste of aspirin as a child that I have only to think of aspirin to make myself feel really sick. My best friend, on the other hand, adores the taste of aspirin. Perhaps he is lucky. And aspirin is very cheap.