2 articles on aspirin and colon/breast cancer
1. looked at 5 trials
using aspirin, at least 75mg/d, to decrease vasc events, with 6.5 yrs
followup. Many old studies suggested dec
in colon ca with asa or nsaids, most with positive results. This study of 17K
pts found 36% dec risk of distant mets overall in pts with cancer, with the
vast majority of effect in adenoca -- 48% dec risk of metastases in those with
adenoca. Esp effective in those without mets at diagnosis (50% decrease).
Essentially all of the graphs show continuing divergence of curves for the
first approx 8 years, then plateauing, for lung, bone, brain, and other
mets. The total number of cancers
detected and elligible for analysis was 775. (they do not give absolute risk
reductions, but to my simplistic analysis, about 5% of pts had cancer, about
50% reduction, so on the order of 2.5% of population with benefit).
Those on lower dose
aspirin did the best. For the most
common adenocarcinomas (esp those without mets already), the results were
consistent (colorectal 73% reduction, breast 84% reduction, prostate 66%
reduction). Pretty impressive. See aspirin cancer mets lancet 2012 in
dropbox.
2. study on cancer
incidence in pts taking daily aspirin, short-term effects. In 34 trials of 69K
pts, 15% dec cancer deaths, esp after 5 yrs. In primary prevention trials of
low dose asa (6 trials, 36K pts), after 3 years cancer incidence dec 24%. Initially
the benefit of asa was offset by inc bleeding, but that outcome diminished
after 3 years, with continuing benefit in cancer incidence. For some reason
(??) case-fatality rate from major extracranial bleeds lower on asa, though
there was twice the risk of extracranial bleeds in the 1st 3 yrs, no increased
risk afterwards.(intracranial bleeds included in "major vascular
events" category). Curves on cancer incidence ess the same for first 4
years, then diverge and stay diverged, demonstrating consistent benefit from
aspirin. Subgroup analyses (men/women, age more or less than 60, smoker) all
show the same, with no real effect for 1st 3 years, but after 3 years there is
a consistent absolute reduction of 3 cancers/1000-patient years. See aspirin and cancer incidence lancet
2012 in dropbox.
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