Aspirin can reduce the risk of cancer - and we're starting to understand why

https://www.bbc.com/future/article/20260420-cancer-how-aspirin-may-be-a-powerful-new-weapon-against-tumours

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It is here that John Burn's study of patients with Lynch Syndrome, which vastly increases the risk of colorectal and other forms of cancer, enters the picture. In 2020, Burn published the results of a landmark randomised controlled trial of 861 patients with the condition. Following the participants for 10 years, his team discovered that people who had taken a daily 600mg dose of aspirin for at least two years effectively halved their risk of colorectal cancer.

His team have since conducted a second trial, which is currently under peer review. The early results suggest that a much lower dose of aspirin (75-100mg) is just as effective – if not more. "The people who took aspirin for two years had 50% fewer cancers in the colon," he says. "What we want to do is keep on going for a few more years because the data is going to get better as time goes on.” (Nick James, the very first patient to enter the trial, was among the ones who appeared to have benefited.)
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Given these results, it is natural to wonder whether aspirin could benefit other patient groups. Martling has investigated whether aspirin can reduce the risk of metastasis in people who've already had a diagnosis of colorectal cancer. Her team focused on people with common mutations in their bowel or rectal tumours. "Of all patients getting colorectal cancer, 40% have one of the mutations we have studied," she explains. Previous research had suggested these people may respond particularly well to aspirin.

The three-year randomised controlled trial involved 2,980 patients, with one group taking 160mg of aspirin daily, starting within three months of surgery, and the other receiving a placebo. The aspirin-treated group had less than half the risk of recurrence – a highly significant effect size. "That's a large group of the patients," says Martling. What's more, both Martling's and Burn's trials showed very few cases of adverse effects in the people taking aspirin.
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