21 October 2010 Last updated at 23:20 GMT
Aspirin 'helps protect against bowel cancer'
By Nick Triggle Health reporter, BBC News
A daily aspirin tablet may help prevent bowel cancer, a study suggests.
Oxford University found it cut cases by a quarter and deaths by more than a third in a review of 14,000 patients.
Aspirins are already widely used to help protect people against strokes and heart problems, although many healthy middle-aged people do not take them because of the risk of side-effects.
But researchers said their findings - published by the Lancet - "tipped the balance" in favour of taking them.
They followed up four study groups over a period of 20 years to identify the impact of regular small doses of of the drug - the tablets given for medical reasons are often a quarter of a strength of those used to treat headaches.
They found it reduced the risk of the incidence of bowel cancer by 24% and of dying from the disease by 35%.
And even though regular aspirin use can have side-effects, the researchers said it was still worthwhile as on such low doses these tended to be relatively minor, such as bruising or nose bleeds.
One in 20 people in the UK develops bowel cancer over their lifetime, making it the third most common cancer. About 16,000 people die each year as a result of it.
The findings build on previous research on the issue, and come after the government announced earlier this month it was looking to start a new screening programme for bowel cancer for 55-year-olds.
Lead researcher Professor Peter Rothwell said the screening would provide the perfect opportunity for doctors to discuss with their patients about whether to take aspirin.
"To date, for healthy middle-aged people it has been a fine balance as to whether to take aspirins, but this tips it in my view.
"There is a small benefit for vascular disease and now we know a big benefit for this cancer. In the future, I am sure it will be shown that aspirin helps prevent other cancers too."
'Talk to GP'
He added those with a high risk of bowel cancer, including the obese and those with a family history of the disease, should give aspirin treatment a particular consideration.
Mark Flannagan, chief executive of Beating Bowel Cancer, said they were "very positive" findings and giving aspirin alongside the new screening programme should be looked at.
But he added: "Anyone considering starting a course of medication should first consult their GP."
The Lancet, Early Online Publication, 22 October 2010
doi:10.1016/S0140-6736(10)61543-7Cite or Link Using DOI
Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials
Prof Peter M Rothwell FMedSci a Corresponding AuthorEmail Address, Michelle Wilson BSc a, Carl-Eric Elwin MD b, Prof Bo Norrving PhD c, Prof Ale Algra MD d, Prof Charles P Warlow FMedSci e, Prof Tom W Meade FRS f
High-dose aspirin (?500 mg daily) reduces long-term incidence of colorectal cancer, but adverse effects might limit its potential for long-term prevention. The long-term effectiveness of lower doses (75?300 mg daily) is unknown. We assessed the effects of aspirin on incidence and mortality due to colorectal cancer in relation to dose, duration of treatment, and site of tumour.
We followed up four randomised trials of aspirin versus control in primary (Thrombosis Prevention Trial, British Doctors Aspirin Trial) and secondary (Swedish Aspirin Low Dose Trial, UK-TIA Aspirin Trial) prevention of vascular events and one trial of different doses of aspirin (Dutch TIA Aspirin Trial) and established the effect of aspirin on risk of colorectal cancer over 20 years during and after the trials by analysis of pooled individual patient data.
In the four trials of aspirin versus control (mean duration of scheduled treatment 6・0 years), 391 (2・8%) of 14 033 patients had colorectal cancer during a median follow-up of 18・3 years. Allocation to aspirin reduced the 20-year risk of colon cancer (incidence hazard ratio [HR] 0・76, 0・60?0・96, p=0・02; mortality HR 0・65, 0・48?0・88, p=0・005), but not rectal cancer (0・90, 0・63?1・30, p=0・58; 0・80, 0・50?1・28, p=0・35). Where subsite data were available, aspirin reduced risk of cancer of the proximal colon (0・45, 0・28?0・74, p=0・001; 0・34, 0・18?0・66, p=0・001), but not the distal colon (1・10, 0・73?1・64, p=0・66; 1・21, 0・66?2・24, p=0・54; for incidence difference p=0・04, for mortality difference p=0・01). However, benefit increased with scheduled duration of treatment, such that allocation to aspirin of 5 years or longer reduced risk of proximal colon cancer by about 70% (0・35, 0・20?0・63; 0・24, 0・11?0・52; both p<0・0001) and also reduced risk of rectal cancer (0・58, 0・36?0・92, p=0・02; 0・47, 0・26?0・87, p=0・01). There was no increase in benefit at doses of aspirin greater than 75 mg daily, with an absolute reduction of 1・76% (0・61?2・91; p=0・001) in 20-year risk of any fatal colorectal cancer after 5-years scheduled treatment with 75?300 mg daily. However, risk of fatal colorectal cancer was higher on 30 mg versus 283 mg daily on long-term follow-up of the Dutch TIA trial (odds ratio 2・02, 0・70?6・05, p=0・15).
Aspirin taken for several years at doses of at least 75 mg daily reduced long-term incidence and mortality due to colorectal cancer. Benefit was greatest for cancers of the proximal colon, which are not otherwise prevented effectively by screening with sigmoidoscopy or colonoscopy.
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