Aspirin
Bowel Cancer and Aspirin
The potential benefits of Aspirin in preventing cancer have been
known about for several years, including as a result of a number of
trials and studies. However, the precise dosage required and the
duration of treatment needed have not been clear, because of the
variability of previous studies.
Until recently, these theoretical benefits were offset by the
risk of adverse side effects, such as internal bleeding, caused as
a result of the higher dosage of Aspirin (over 300 milligrams) that
was believed to be needed to achieve them.
However, recent studies published in the Lancet have shown that
a low daily dosage of Aspirin (75 mgs; the same as junior aspirin)
taken over a five year period, can reduce longer term (i.e. 20
year) incidence and deaths from the disease, including bowel
cancer.
Below, our Chief Medical Advisor, Rob Glynne Jones,
answers some questions on Aspirin and cancer:
Who has carried out these studies into Aspirin and
cancer?
The studies have been carried out by Professor Rothwell and
colleagues at John Radcliffe Hospital, Oxford and other centres.
Further studies by the same authors are expected to be published
during 2011.
What do these studies show?
They show that a low daily dosage of Aspirin (75 mgs), taken over a
five year period, can reduce the long term (i.e. 20 year) incidence
of the disease by 24%; deaths from the disease by 35%; and the odds
of developing bowel cancer from one in 28 people to one in 66
people.
Should I start taking Aspirin to help prevent bowel
cancer?
Even low dose aspirin has a number of effects on the body,
including on normal clotting processes. It would be unwise,
therefore, to take aspirin on a regular basis, including as a means
of reducing your cancer risk, without discussing it first with your
GP.
What are the risks involved in taking
Aspirin?
Taking Aspirin increases the risk of developing ulcers in the
stomach or gut, which can lead to bleeding. The risk of bleeding
increases if the dosage of Aspirin increases, which is why a
smaller dosage of 75 mgs is safer than a larger dosage.
Around one in a hundred people are allergic to Aspirin and one
in ten people with asthma who take Aspirin find that it makes their
asthma worse. As already stated above, Aspirin interferes with the
normal clotting process and can make you bleed you more easily.
Is Aspirin a cure for bowel cancer?
While this news is very exciting and encouraging, Aspirin is not a
cure for colorectal cancer and it may help to prevent cancers
occurring in only part of the bowel. We would, therefore, strongly
encourage people to continue to be vigilant about the disease; to
act upon their symptoms and concerns and not ignore them; and, if
eligible, to take part in the Bowel Cancer Screening Programme.
What does Aspirin do to help prevent
cancer?
We are not entirely sure how Aspirin works in helping to prevent
cancer. One theory is that it can reduce persistent inflammation in
the body, which is one of the causes of cancer.
What are Aspirin's other benefits?
Aspirin is best known for being an effective painkiller, which it
achieves by blocking a pain generating enzyme in the body called
COX-2. Aspirin can also lower the risk of heart disease, strokes
and dementia.
What is Bowel Cancer UK's response to the
studies?
We welcome these studies. It is encouraging that a lower dosage of
Aspirin, and one with a reduced risk of side effects, appears to
have such a positive effect on preventing bowel cancer. We look
forward to the results of future studies refining our understanding
of this process.
Is age a factor in people benefitting from
Aspirin?
While Aspirin benefits people of all ages, it appears to have the
greatest impact in people aged over 65, in the main because older
people have an increased risk of cancer related death. As the
statistics show, Aspirin reduces the risk of dying from cancer by
7% for people over 65; and by 3.5% for all the people in the trials
combined.
What about longer term treatment with
Aspirin?
The authors of the study believe that if people are treated with
lower dose aspirin for 20 to 30 years, those who start to do so in
their late 40s or 50s are the most likely to benefit longer term.
They also say that the risk of death from bowel cancer is reduced
by about 40% if people take Aspirin over 20 years.
Does Aspirin prevent tumours in all areas of the
bowel?
While Aspirin might help prevent tumours in all areas of the bowel
(e.g. in the colon and the rectum),the evidence suggests that it is
most effective in preventing tumours in the first part of the
bowel, i.e. in the ascending and transverse colon.
Reference: Rothwell, P., Fowkes, F., Belch, J., Ogawa, H.,
Warlow, C., & Meade, T. (2010). Effect of daily aspirin on
long-term risk of death due to cancer: analysis of individual
patient data from randomised trials The Lancet DOI:
10.1016/S0140-6736(10)62110-1
Last updated 17th January 2011
