Men and women with a range of cancers who took the anti-inflammatory pain killer experienced a “significant” survival benefit compared with those who did not.
Researchers analysed data from nearly 14,000 patients in the Netherlands, around half of whom were in the habit of taking aspirin.
Over a typical follow-up period of four years, those using the drug after their diagnosis were twice as likely to still be alive as non-users.
The impact of aspirin on survival was seen after adjusting for factors such as gender, age, stage of cancer, treatments and other medical conditions that could have influenced death rates.
Trial co-ordinator Dr Martine Frouws, from Leiden University in the Netherlands – who presented the findings at the 2015 European Cancer Congress in Vienna, said: “Now we would like to analyse tumour material from these patients to try and discover which ones would benefit from aspirin treatment.
“Through studying the characteristics of tumours in patients where aspirin was beneficial, we should be able to identify patients who could profit from such treatment in the future.
“Given that aspirin is a cheap, off-patent drug with relatively few side-effects, this will have a great impact on healthcare systems as well as patients.”
The most common tumour sites for patients in the study were the colon, rectum and oesophagus. A new, randomised, controlled trial is currently investigating the effect of a daily low dose of 80 milligrams of aspirin on the survival of elderly patients with bowel cancer in the country.
In this trial, the effects of aspirin and a dummy “placebo” will be compared. Researchers, who plan at a later date to expand the study to include gastrointestinal cancers, hope to provide “convincing proof” that more patients can benefit from aspirin treatment.
Professor Peter Naredi, scientific co-chair of the Congress, said: “We have good evidence that the frequent use of aspirin in the population can prevent some cases of colorectal (bowel) cancer.
“Now, Dr Frouws and colleagues show that in more than 13,000 patients who were diagnosed with a gastrointestinal cancer, aspirin also improved survival compared with those who did not use it.
“With more and more data to support the beneficial role of aspirin, we must consider whether we should recommend it to a wider public.”
Bowel cancer is one of the most common types of cancer diagnosed in the UK, with around 40,000 new cases diagnosed every year.
Around one in every 20 people in the United Kingdom will develop bowel cancer during their lifetime.