New research has shown that bowel cancer patients who take daily aspirin could cut their chance of dying from the disease by about a third. But experts say it is too soon to start routinely offering it for bowel cancer.
There is previous evidence suggesting aspirin might prevent certain cancers from developing in the first place. And more recent work suggests it might also work as a cancer therapy - slowing down or preventing a cancer's spread. But the drug can also have unpleasant and dangerous side effects, causing irritation of the stomach lining and internal bleeds in a very small minority of patients.
A study in the British Journal of Cancer looked at 4,500 bowel cancer patients living in The Netherlands. All of the patients on aspirin were taking a low dose - 80mg or less a day - something already recommended for people with heart disease.
The study spanned over a decade. A quarter of the patients did not use aspirin, a quarter only took aspirin after being diagnosed with bowel cancer, and the remaining half took aspirin both before and after their diagnosis. Most of the patients on aspirin had been taking it to prevent cardiovascular disease-related problems like stroke or heart attack.
Results showed that taking aspirin for any length of time after diagnosis cut the chance of dying from bowel cancer by 23%. The patients who took a daily dose of aspirin for at least nine months after their diagnosis cut their chance of dying from the disease by 30%. Taking aspirin only after bowel cancer had been detected had a bigger impact on reducing mortality compared with when aspirin was taken before and after diagnosis - reducing death risk by 12%. This may be because those who took aspirin and still got bowel cancer had a particularly aggressive form of tumour that did not respond as well to aspirin, say the researchers.
Lead researcher Dr Gerrit-Jan Liefers, of the Leiden University Medical Centre, said, “Our work adds to growing evidence that aspirin not only can prevent cancer from occurring but if it is there it can help prevent it spreading.” He said aspirin should not be seen as an alternative to other treatments, such as chemotherapy, but could be a useful additional treatment.
“It's possible that some older people may have other health problems which mean that they are not well enough to have chemotherapy. Bowel cancer is more common in older people so these results could be a big advance in treatment of the disease, particularly in this group. But we need further research to confirm this,” Leifers said. He said they now planned to hold a randomised controlled trial - the “gold standard” in medical research - to look at how well aspirin fared against a dummy drug in people aged over 70 with bowel cancer.
Sarah Lyness of Cancer Research UK said, “This latest study adds to the growing evidence about the benefits of aspirin. But we are not yet at the point where we would recommend people start taking aspirin to reduce their chances of developing cancer.” She explained, “There are still questions we need to answer about the side effects, such as internal bleeding, who might benefit most from taking aspirin, who might be harmed, what dose and how long people some people might want to take it for. Anyone thinking of taking aspirin to cut their risk of cancer should talk to their GP first. People with cancer should be aware that aspirin can increase the chances of complications before surgery or other cancer treatments such as chemotherapy, and should discuss this with their specialist.” “In the meantime, there are many ways we can take to lower our risk of developing cancer - not smoking, cutting back on alcohol and keeping a healthy weight can help stack the odds in our favour,” she added.
In yet another study of more than 1,200 Asian women, it was found that those who took aspirin at least a couple of times a week had a much lower risk of developing lung cancer -- whether or not they had ever smoked.
The findings, which link regularly taking aspirin to a risk reduction of 50 percent or more, do not prove that aspirin directly protects against lung cancer. There may be other explanations for the connection. Aspirin use is also linked to to lower risks of certain cancers, including colon, prostate and esophageal cancers.
Still, experts say it's too early to recommend widespread aspirin use for cutting cancer risk. “The question about whether aspirin use protects against lung cancer is still open to considerable debate at this point, and the published evidence to date is not conclusive,” Dr. Wei-Yen Lim, who led the new study, said in an email. Avoiding tobacco smoke remains the best way to protect yourself, said Lim, of the National University of Singapore.
Published in the journal Lung Cancer, the study included 398 Chinese women diagnosed with lung cancer and 814 cancer-free women. Lim's team found that women who had used aspirin regularly -- at least twice a week for one month or longer -- were less likely to have lung cancer. Among women who'd never smoked, the odds were 50 percent lower for aspirin users versus non-users. And among smokers, aspirin use was tied to a 62 percent lower risk of lung cancer.
The researchers were able to account for some other factors, like the women's age, education and fruit and vegetable intake. But there could still be other differences that would help explain why aspirin users had a lower lung cancer risk, according to Lim.
Dr. Andrew T. Chan of Harvard Medical School, who was not involved in the study, said that the evidence on aspirin and lung cancer has been “mixed.” “The number-one thing a person can do to minimize the risk of lung cancer is to not smoke,” he said in an interview.
The U.S. Preventive Services Task Force recommends that men age 45 to 79 take aspirin to prevent heart attacks, as long as their personal benefit is likely to outweigh the risk of bleeding. For women age 55 to 79, aspirin is recommended to prevent ischemic strokes, with the same caveat. Lim said that if your doctor has recommended aspirin to you, stick with that advice. “For people who are currently well,” the researcher said, “we do not recommend taking aspirin to reduce their risk of lung cancer, as the effect of aspirin on lung cancer is still being evaluated.”
New trials show promise for immune checkpoint blockers in early-stage lung cancer