How Good Is Aspirin Against Cancer? You Might Be Amazed!

In 1993 we published a book with Tom Ferguson, MD, called The Aspirin Handbook (Bantam Books). In it we pointed out that there was an impressive amount of research supporting the beneficial effects of aspirin against cancer. We wrote: “You can talk about heart attack and stroke prevention until you are blue in the face, but if you really want to catch someone’s attention all you have to do is whisper that aspirin could prevent cancer or reduce the likelihood it will return.” We have been puzzled that most healthcare professionals seem unimpressed with this amazing aspect of aspirin’s actions.

The Unenthusiastic Reaction to Aspirin Against Cancer:

Over the last four decades the data keep accumulating that aspirin has impressive anticancer activity. What disappoints us is that in general, health professionals have ignored the vast amount of research suggesting that aspirin can both prevent cancer as well as reduce the likelihood of its spread. More about the history of aspirin against cancer in a moment. First, though, the latest research!

Aspirin has been available for well over 100 years, but the active ingredient has been used by native healers for thousands of years. In 1991 a research article in the New England Journal of Medicine reported that regular aspirin users were 40 to 50 percent less likely to die of colon cancer.

Aspirin Against Cancer Recurrence:

Now, 34 years later, another research paper in the New England Journal of Medicine, Sept. 18, 2025 reports that people taking aspirin had a significantly lower chance of colorectal cancer recurrence.

Swedish scientists recruited patients after they had their tumors removed. The researchers were specifically looking for cancers that had a particular hotspot mutation called PIK3CA. The aspirin dose was 160 mg or roughly half a standard-strength tablet daily for 3 years. 626 patients were randomly assigned to receive either aspirin or placebo.

7.7% of people taking aspirin experienced a recurrence of their colorectal cancer whereas 14.1% of those on placebo had a recurrence. That was about a 50% relative risk reduction. 43% of the participants taking aspirin experienced a nonsevere side effect compared to 35% of those on placebo. Serious adverse events occurred in 17% in aspirin takers compared to 12% of placebo recipients.

The authors conclude that low-dose aspirin represents an effective, low-cost treatment approach to prevent colorectal cancer recurrence in high-risk genetically selected patients.

Here is a very stuffy, scientific description of why their aspirin findings might be trustworthy:

“These prospective data support the hypothesis that the regular use of aspirin may decrease the risk of fatal colon cancer. Several aspects of the data suggest that the relation may be causal. These include the strength of the association, its internal consistency when the data were analyzed in a variety of ways, the statistically significant dose–response trends in both men and women, the persistence of the decreased risk after control for other risk factors, and the similarity between these findings and those in two previously published case–control studies.”

Aspirin Against Cancer of the Liver:

One important complication of hepatitis B is liver cancer. Now, researchers report that aspirin can significantly lower the risk of liver cancer. By the way, lest you think that isn’t a big deal, the lead investigator points out that:

“Liver cancer is the second leading cause of cancer death worldwide”

The investigators utilized medical records from the national Health Insurance Research Database of Taipei. There were more than 200,000 people with hepatitis B between 1998 and 2012, and 1,553 had received daily aspirin for at least 90 days during that time.

Their records were matched to those of 6,212 patients who had not taken aspirin or other anti-platelet drugs. Those on aspirin were much less likely to develop liver cancer. Their rate of hepatocellular carcinoma was 2.86 percent, compared to 5.59 percent for other hepatitis B patients. The risk of cancer was cut nearly in half for people taking aspirin (Hepatology, Oct. 2017). Does that sound familiar?

[Presented at The Liver Meeting, Washington, DC, Oct. 23, 2017]

The History of Aspirin Against Cancer:

Other studies have revealed that aspirin lowers the risk of cancers of the colon, rectum, esophagus, stomach, breast, lungs, pancreas and ovaries.

In 1993 we wrote this:

“Researchers have known for over a decade that aspirin and other non steroidal-anti-inflammatory drugs (NSAIDs) could block the growth of cancer in rodents. These tumors were caused by administering artificial carcinogens. The animals were also being given an NSAID. When the NSAID was stopped, the anticancer protection disappeared.

“By 1998 there were epidemiological data that suggested aspirin could reduce colon and rectal cancer in humans, but because the work was carried out in Melbourne, Australia, it did not receive much attention in the United States (Cancer Research, Aug. 1, 1988). Finally, in 1991, a report in the Journal of the National Cancer Institute (March 6, 1991) that regular use of aspirin could reduce colorectal cancer by 50 percent got public recognition.

“But it takes the seal of approval from the New England Journal of Medicine to really focus the attention of the medical profession and the media. That happened December 5, 1991, when Dr. Michael Thun and his colleagues at the American Cancer Society also reported a 40 to 50 percent reduction in fatal colon cancer.

“In 1992 epidemiologists for the American Cancer Society reported that men and women who ate fruits, vegetables, and high-fiber foods and also took at least 16 aspirin tablets a month could have a major impact on colon cancer (2.5 to 2.9 times less cancer). Their research was published in The Journal of the National Cancer Institute, Oct. 7, 1992. An additional study [in 1992] confirmed that as little as one regular aspirin tablet a week could reduce colon cancer by 50 percent while daily aspirin ‘cut the risk by 63 percent.’ Now that’s impressive!”

Aspirin Against Cancer Since 1992:

Over the last 35 years there have been hundreds, perhaps thousands, of journal articles about aspirin against cancer. A review in Lancet Oncology (Aug., 2017) titled “Preventive Therapy for Cancer” noted:

“Therapeutic cancer prevention is a developing area that can gain a lot from the successes in the prevention of cardiovascular diseases. Although weight control and physical activity are important in the prevention of both diseases, several other preventive measures exist. Low-dose aspirin for cancer prevention is often cited as the most important approach in terms of population benefit, and should be offered to those older than 50 years of age without hypertension or risk factors for gastrointestinal bleeding.”

The Downsides of Aspirin:

Like all NSAIDs, aspirin can be hard on the digestive tract. Even low-dose enteric-coated aspirin can cause ulcers. Some people develop life-threatening bleeding ulcers or perforations. There is also a concern that aspirin could cause a bleeding (hemorrhagic) stroke. While rare, it is extremely dangerous!

That is why anyone who plans to take aspirin regularly must do so under medical supervision. This is not a do-it-yourself proposition!

Aspirin can also interact dangerously with other medicines. Both a physician and pharmacist should make sure that aspirin will not cause more harm than good or interact with other drugs you may be taking.

That said, we have long maintained that “aspirin in the Rodney Dangerfield of the drug world.” Rodney was an amazing actor and comedian who long maintained that:

“I don’t get no respect!”

We do not understand why so many healthcare professionals look down their noses at aspirin. Perhaps it’s because aspirin is available over the counter. It’s also inexpensive. We suspect that if a prescription drug had the anti-cancer track record that aspirin does, it would be a) highly praised b) extremely expensive.

We have a free Guide to Key Aspirin Information available at this link. It is a bit old, but there is still interesting information and it is free!

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