Three new studies by researchers at Oxford University reveals, aspirin – the common pain killer – could be effective not just as preventive medicine for cancer, but as an additional treatment for those with the disease.
The studies by Professor Peter Rothwell of the Nuffield Department of Clinical Neurosciences and his colleagues show aspirin can reduce chances of spread of tumours to other parts of the body. The research papers were published on Wednesday (March 21) in the medical journal The Lancet and The Lancet Oncology.
“No drug has been shown before to prevent distant metastasis and so these findings should focus future research on this crucial aspect of treatment of patients with cancer that hasn’t already spread,” said Professor Rothwell. “We argue in our papers that new trials are still required to confirm the benefit – but such trials should be done urgently.”
Earlier studies have established aspirin reduces the long-term risk from cancer, but these effects don’t appear until about 8-10 years after taking a daily low dose of the drug. The short-term effects of aspirin were less certain.
“What we have now shown is that aspirin also has short-term effects, which are manifest after only 2-3 years,” said Professor Rothwell.
Aspirin, in doses, is also known to help prevent heart disease and stroke and for the work on cancer, the researchers used data from many of the trials to establish this effect. But among people who don’t have a history of heart problem, the slight benefits of aspirin are largely balanced out by the increased risk of stomach bleeds.
The new information about aspirin and cancer could begin to change the overall assessment, the researchers believe.
Professor Rothwell says, the benefits of daily aspirin in reducing cancer risks are larger in absolute terms than the benefits in preventing heart diseases and stroke, particularly with prolonged use.
The first Lancet paper used data for all participants in 51 randomised clinical trials comparing the effect of taking aspirin every day against no aspirin. While these trials sought to see if aspirin prevented vascular events such as heart attacks, it also included data on cancer deaths. The team found, aspirin reduced the risk of death from cancer by 15 percent. The reduction in risk improved over time, reaching 37% for those on aspirin for 5 years and more.
Daily low-doses of aspirin also reduced the occurrence of cancer, not just deaths from cancer. The incidence of cancers dropped by around a quarter from 3 years and onwards, with similar reductions in men (23%) and women (25%).
The second paper in The Lancet reports on aspirin’s effect on the spread of cancer to other organs in the body, a process known as metastasis.
“We show that aspirin reduces the likelihood that cancers will spread to distant organs by about 40-50%. This is important because it is this process of spread of cancer, or “metastasis”, which most commonly kills people with cancer,” said Professor Rothwell.
The third study published in The Lancet Oncology, also looked at aspirin’s effect on cancer risk. In this case, the researchers carried out a systematic review of a different type of medical study – they looked at observational studies rather than randomized trials and the results were matching, confirming a similar reduction in risk.
“In terms of preventing spread of cancer, the data suggests that the effect is largest in adenocarcinomas. These include cancer of the gut, particularly colorectal cancer, some cancers of the lung and most cancers of the breast and prostate,” explained Professor Rothwell. “In terms of preventing the longer-term development of news cancers, the largest reductions are seen in risk of colorectal cancer and oesophageal cancer, with smaller effects on several other common cancers.”