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Long-term low-dose aspirin ‘reduces colorectal cancer risk’

Long term, low-dose aspirin taken on alternate days ‘may reduce risk for colorectal cancer in healthy women’, claims a new study.

The study

The follow-up to the Women’s Health Study allocated 19,934 female healthcare professionals aged 45 years or older to 100 mg day aspirin on alternate days and 19,942 to placebo for a median follow up of 10 years. Post-trial questionnaires asked women about any diagnosis of colon polyp, peptic ulcer or gastrointestinal bleeding.  The questionnaires were sent at six and 12 month and then yearly.

The findings

There were 5,071 cancer cases confirmed during the 18 years follow up of which 2,070 were breast cancer, 451 colorectal cancer and 431 lung cancer as well as 1,391 cancer deaths. There was no association between aspirin use and total number of cancer cases (HR 0.97), breast cancer (HR 0.98) or lung cancer (HR 1.04). But there was a reduction in colorectal cancer in the group who took long-term aspirin (HR 0.80) especially for proximal colon cancer (HR 0.73) and the reduction was observed after 10 years. Women who continued to use aspirin after the trial had a 42% lower rate of colorectal cancer (HR 0.58) compared with 33% in the group who did not use aspirin post-trial (HR 0.67). There were more gastrointestinal bleedings (HR 1.14) and peptic ulcers (HR 1.17) in the aspirin group.

What this means for GPs

The authors commented: ‘Long-term use of alternate-day, low-dose aspirin may reduce risk for colorectal cancer in healthy women’ and warned: ‘Aspirin’ adverse effects, however, cannot be forgotten.’

Expert comment

In an editorial, Professor Peter Rothwell, professor of clinical neurology at the University of Oxford said: ‘The findings reinforce the need to consider risks and benefits of aspirin separately in men and women, and treatment decisions in individuals should now reflect what is known about their risk for gastrointestinal cancer as well as their vascular risk.’

Ann Intern Med 2013; 159: 77-85

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