In a study of over 300,000 people, the researchers found that people who had taken aspirin at least once in the previous year were significantly less likely to get non-cardia gastric cancer - cancer of the middle or lower parts of the stomach.
There was also a 32 per cent reduction for the same type of stomach cancer in people who used other types of non-steroidal anti-inflammatory drugs - or NSAIDs.
In contrast to results of previous studies, the researchers found that aspirin does not protect against oesophageal cancer and cardia gastric cancer, which is cancer of the top of the stomach.
Taking aspirin regularly has been found to cut the risk of bowel cancer, but it is not currently recommended because side effects could include bleeding within the abdomen.
Now, scientists believe that placebo controlled trials, which would assess risks and benefits should be conducted to see if NSAIDs can be used to protect against stomach and oesophageal cancers.
Five year survival rates for these cancers are 15 and 8 per cent in the UK respectively, so research in how to prevent the disease is important.
Study author Dr Christian Abnet, based at the National Cancer Institute in America, said: "We found that the risk of non-cardia stomach cancer was lower in people who had taken aspirin, and this risk lowered the more regularly they took it.
Interestingly, our results didn't show a significant cut in the risk of oesophageal or cardia stomach cancer, so it's important that we continue to review data that suggests otherwise.
"The number of people who survive at least five years following a diagnosis of stomach or oesophageal cancer is low, so it's important to increase our understanding of ways to prevent the disease and to investigate aspirin as a possible preventative drug."
The rate of non-cardia stomach cancer calculated in this study was 7 per 100,000 person-years for aspirin users, compared with 11 per 100,000 person-years for non-users.
The figures were calculated from a study of more than 311,000 people in America and an analysis of 17 published studies on the topic.
Each year in the UK, around 8,000 people are diagnosed with stomach cancer, and around 5,250 people die from the disease.
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "It's far too early to recommend that people take aspirin to protect themselves from these cancers. In cancers where survival is low, understanding how to prevent the disease is crucial, but more research is needed to discover how side effects can be balanced with the benefits.
We urge people to speak to their doctor before taking aspirin regularly."
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