All you need to read in the other general journalsBMJ 2012; 344 doi: http://dx.doi.org/10.1136/bmj.e2269 (Published 28 March 2012) Cite this as: BMJ 2012;344:e2269
Further evidence that aspirin helps prevent cancer
Further evidence of the anticancer effects of aspirin have emerged from a series of new meta-analyses reporting that an aspirin a day reduces deaths from cancer (odds ratio 0.85, 95% CI 0.76 to 0.96) and the incidence of cancer (0.76, 0.66 to 0.88), and can even help prevent the spread of existing adenocarcinomas (hazard ratio for subsequent metastasis 0.45, 0.28 to 0.72).
The evidence looked strongest for colorectal cancer but extended to a range of other types, including other gastrointestinal cancers and breast cancer. The new analyses strengthened previously weak evidence for an anticancer effect in women.
The authors began with 51 randomised trials of daily aspirin at any dose for the primary or secondary prevention of vascular disease. A reduction in cancer deaths emerged after five years of treatment, a reduction in incidence emerged after three.
Aspirin was associated with more serious bleeds than the control treatments, but only during the first three years. Bleeding risk seemed to fall away after that, and so did the vascular benefits, leaving just aspirin’s beneficial effects on cancer risk.⇑ In one analysis, major extracranial bleeds looked less lethal among adults taking aspirin than among controls (case fatality 8/203 v 15/132, odds ratio 0.32, 0.12 to 0.83).
Should we all be taking an aspirin a day to protect ourselves from cancer? It’s still too early for that, says a linked commentary (doi:10.1016/S0140-6736(11)61654-1). These analyses, though impressive, were confined to trials of daily aspirin and had to exclude two of the biggest—the Women’s Health Study and the Physicians Health Study—because they tested an aspirin every other day instead. Neither of these trials reported a lower risk of cancer or cancer death among participants taking aspirin.