CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 2, March/April 2011
110
AFRICA
Substantial evidence for colorectal cancer reduction with daily
low-dose aspirin
High-dose aspirin (
≥
500 mg daily) taken
for a period of five years has been shown
in long-term follow-up studies to reduce
the risk of colorectal cancer in the next
decades of the patient’s life. However, the
greater risk of bleeding complications at
this high dose reduces aspirin’s potential
in primary prevention of cancers.
New data from four trials of aspirin,
1
using daily dosages from 75 to 300 mg
were compared to the high-dose aspirin
studies and showed:
•
75 mg aspirin taken daily is as effec-
tive as high-dose aspirin in reducing
the 20-year incidence of colorectal
cancer (by 30%) if taken for approxi-
mately five years.
•
Not only did the lower dose of aspirin
reduce the incidence of these cancers,
it also reduced mortality from colorec-
tal cancer.
•
The reduction in fatal colorectal cancer
tended to be greater than the reduction
in incidence.
•
Very low daily doses of aspirin tended
to not be effective in the prevention of
colorectal cancer.
•
The reductions in both incidence and
death due to colorectal cancer were
greater for proximal cancer tumours
than distal colon or rectal tumours.
•
The reduction in 20-year risk of death
due to colorectal cancer was larger
than expected.
•
Larger doses, above 300 to 1 200 mg
daily, did not confer any additional
benefits in terms of reduced incidence
or deaths from colorectal cancer.
The long-term absolute risk reduction of
1–5% after long-term, low-dose aspirin
treatment has implications for clinical
practice. It adds to the primary preventa-
tive benefits of aspirin and may tip the
balance in favour of aspirin compared to
newer anti-platelet agents.
2
J Aalbers, Special Assignments Editor
1. Rothwell PM, Wilson M, Elwin CE,
Norrving B,
et al
. Long-term effect of aspirin
on colorectal cancer incidence and mortal-
ity: 20-year follow-up of five randomised
trials.
Lancet
. Published online Oct 22, 2010.
DOI:10.1016/S0140-6736(10)61543-7.
2. Benamouzig R, Uzzan B. Aspirin to
prevent colorectal cancer: time to act?
Lancet
. Published online Oct 22, 2010.
DOI:10.1016/50140-6736(10)61509-7.
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