Study: Aspirin Can Lower Cancer Risk

Three studies published today conclude that taking aspirin every day may reduce the risk of cancer and prevent cancer from spreading. However, long-term aspirin use can have serious side effects and should not be taken regularly without talking to a doctor first.

In one of the studies, published in The Lancet, researchers from the University of Oxford analyzed patient records from 51 trials that compared people who took aspirin every day to people who took no aspirin. They found that taking daily low-dose aspirin (less than 300 mg) for 3 years resulted in approximately a 25% lowered risk of developing any type of cancer.

A second article by University of Oxford researchers published in The Lancet looked at the effect of aspirin on cancer metastasis (spread). They found that during an average 6 ½ years of taking aspirin (75mg or more a day), trial participants lowered their risk of metastatic cancer by 36%. The main effect seemed to be on the risk of metastatic adenocarcinoma (a common type of solid cancer that can occur in many areas, including the colon, lung, and prostate), which was lowered by 46%. Researchers also found that daily aspirin lowered the risk of non-metastatic cancer progressing to metastatic cancer, especially in patients with colon cancer.

The third study, published in The Lancet Oncology, also looked at aspirin’s effect on metastasis. The researchers reviewed observational studies as well as randomized trials to draw conclusions regarding less common cancer types and cancer in women. They found significantly lowered risk of cancer and metastasis in colon, throat, gastric, biliary and breast cancer.

The randomized trials reviewed by the researchers were originally done to find out if taking daily aspirin could help prevent heart attacks and strokes. Many people already take a baby aspirin every day, under a doctor’s supervision, to lower their risk of heart disease. This is usually advised when the risk of heart disease is thought to be higher than the risk of possible side effects, such as gastrointestinal bleeding, from taking the aspirin.

Eric Jacobs, PhD, American Cancer Society strategic director of pharmacoepidemiology, said, “This study provides important new evidence that long-term daily aspirin, even at low doses, may lower risk of developing cancer.”

However, he cautioned that the decision to take daily aspirin should be made after talking to a doctor. Jacobs said, “Although the study provides the first evidence from randomized clinical trials that daily aspirin use reduced the occurrence of all cancers combined, any decision about treatment should be made on an individual basis in consultation with your health care professional.”

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: analysis of the time course of risks and benefits in 51 randomised controlled trials. Published online March 21, 2012 in The Lancet. First author: Peter Rothwell, University of Oxford, Oxford, UK.

Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials. Published online March 21, 2012 in The Lancet. First author: Peter Rothwell, University of Oxford, Oxford, UK.

Effects of regular aspirin on long-term cancer incidence and metastasis: a systematic comparison of evidence from observational studies versus randomised trials. Published online March 21, 2012 in The Lancet Oncology. First author: Peter Rothwell, University of Oxford, Oxford, UK.

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