Loading...
For years, doctors have been debating the pros and cons of aspirin. They have long known that this old drug can cause serious gastrointestinal irritation. But epidemiologists have also noted that regular aspirin users appear to suffer fewer digestive tract cancers. Other research suggests aspirin may offer benefit against several different cancers. A new study published in the journal Cancer (April 22, 2024) offers an explanation for how aspirin may help prevent colorectal cancer.
Aspirin Use May Help Prevent Colorectal Cancer:
A meta-analysis concluded that regular aspirin use lowers the risk of colorectal cancer (Annals of Oncology, April 1, 2020). The investigators reviewed 45 observational studies published between January 2011 and March 2018. In addition, they considered 150 additional articles published in a prior meta-analysis. Sixty-six of these provided information on colorectal cancer risk and aspirin use.
When the scientists pooled the data from these 66 studies, they found that regular aspirin use seems to prevent colorectal cancer. The rate of this common malignancy dropped by nearly 30 percent among aspirin users.
In analyzing the eleven studies that provided data on aspirin dose, the researchers found that higher doses appeared more effective than lower doses. That is, people taking 75 mg of aspirin daily lowered their chance of cancer by about 10 percent, whereas those taking 500 mg a day reduced their risk by about 50 percent.
Pharmacologists call this a dose response curve. It is usually considered an important metric when establishing cause and effect.
Fast Forward to 2024:
The authors of the latest study in the journal Cancer point out that:
“Colorectal cancer (CRC) is the third most common cancer and the fourth most frequent cause of cancer deaths worldwide. Several studies have demonstrated that aspirin can play an important role in the chemoprevention of CRC.”
They go on to emphasize:
“In fact, many long-term follow-ups of randomized controlled trials of aspirin versus control have shown that daily aspirin use reduces incidence and mortality from CRC, after a latent period of approximately 8 to 10 years and total cancer mortality from 5 years to 20 years, with reductions in deaths from several other cancers.”
HOW Does Aspirin Prevent Colorectal Cancer (CRC)?
The latest research boils this process down to one sentence:
“These data suggested that regular aspirin use may have an active role in enhancing immunosurveillance against CRC.”
That may seem fairly simple, but trust us when we say that “immunosurveillance” is a very complex and multifactorial process. The idea that aspirin plays a “chemoprevention” role against colorectal cancer is impressive. The authors provide a great deal of detail about the “interrelated mechanisms” whereby aspirin prevents CRC cancer or metastatic disease.
The bottom line seems to be that aspirin helps the immune system seek out cancer cells and attack them. Aspirin also appears capable of limiting metastases or the spread of cancer, especially to lymph nodes.
Does Aspirin Use Lower the Risk of Other Cancers?
People who take aspirin daily develop head and neck cancers as often as people who don’t take it. However, aspirin may help protect users against esophageal cancer and possibly even pancreatic cancer. The researchers point out that longer use (at least five years) appears to offer more protection.
An “umbrella review” published in the journal Heliyon (Jan. 30, 2024) notes that NSAIDs, especially aspirin:
“…might be associated with a decreased risk of several cancers, including the central nervous system, breast, esophageal, gastric, head and neck, hepatocellular, cholangiocarcinoma, colorectal, endometrial, lung, ovary, prostate, and pancreatic cancers, but regular intake of any dose of non-aspirin NSAIDs (NA-NSAIDs) could increase the incidence of kidney cancer.”
As the scientists noted, however, the quality of evidence was “low” or “very low.” In addition, the authors also caution about “gastrointestinal reactions” and “contraindications.”
They go on to state that:
“…it is still too early to recommend that people with no disease regularly consume NSAIDs to prevent cancer.”
A systematic review and meta-analysis of prophylactic aspirin vs. breast cancer concluded (European Journal of Surgical Oncology, Oct. 2023):
“This meta-analysis found an association between aspirin intake and BC [breast cancer] risk reduction. A more favourable outcome was noted with ingestion of greater than 6 tablets of aspirin per week. Aspirin had a significant risk reduction in patients with ER [estrogen receptor] positive tumours compared to ER negative BC.”
Before people get overly enthusiastic about taking aspirin as a chemoprevention strategy, some words of caution. A systematic review and meta-analysis of randomized trials concluded that blood pressure medications (ACE inhibitors and ARBs), metformin for diabetes and nonsteroidal anti-inflammatory drugs (NSAIDs including aspirin) did not improve treatment or prevent recurrence of cancer (Cancer Medicine, March, 2024).
Should You Take Aspirin to Prevent Colorectal Cancer?
Aspirin can provoke serious intestinal irritation, including bleeding ulcers (World Journal of Gastroenterology, March 21, 2013). On the other hand, aspirin may help prevent recurrent heart attacks (Advances in Therapy, Aug. 2019). If one of your parents was diagnosed with colon or rectal cancer, you should talk with your doctor. You’ll need to examine your risk to decide whether to take aspirin to prevent colorectal cancer.
Valeria
I also wonder about using willow bark tea regularly. Do you think it could have similar effects?
Jean
I would love it if you could write more about using aspirin VS other NSAIDS. I take very few medicines, including OTC. Aspirin is my go-to pain medicine if I am in significant pain from the occasional back ache and need to calm it down.
Occasionally I seek medical care to make sure something more serious isn’t going on. Healthcare practitioners are insistent that I take naproxen or a similar drug because “it’s stronger”. I am very hesitant because I have had 3 relatives develop blood clots attributed to other NSAIDS taken for gout. And anyway, a few modest doses of aspirin is very effective.
Any evidence that naproxin is somehow “better” or safer than aspirin?
Thanks!
Joe Graedon
Jean,
We have never seen any decent-sized clinical trial that demonstrates any of the NSAIDs are more effective than aspirin. A lot depends on dose of course. Some of the popular NSAIDs are more likely to cause cardiovascular complications than aspirin.
Art
Can willow bark extract serve as an aspirin substitute?
Terry Graedon
It could, but the proper dose might be hard to calculate.
Theresa
I was taking 8 baby aspirin (the equivalent of an adult dose) each night to help me sleep (aches and pains) for a couple years and had my first colonoscopy without any polyps. (I get a colonoscopy every five years, as I am at a high colon cancer risk). I assume it was the aspirin. However, I have reflux and was having difficulty swallowing. A scope showed tons of swelling and ulcers, so no more aspirin for me.
Barbara
This is a very old rumination. I don’t remember if it was the Nun’s study or the Nurse’s study, but I think this theory was put forward at least 30 years ago. As someone whose mom had colon cancer and has personally had many polyps, mostly adenomas (13 colonoscopies) and one malingnant polyp, these articles catch my attention. I am also aspirin sensitive, so no thanks.
Mary
As a person who had a father with colon cancer, and who has also had polyps myself, including a precancerous one, I would be an ideal candidate for daily aspirin.
However, my family also has a huge history of stroke. You have addressed aspirin therapy as a rather significant risk factor for stroke. I don’t know how to weigh the risk/benefit ratio of aspirin therapy, considering these two factors.
Can you comment? (I actually think you should have at least mentioned the stroke issue, with a link to that article.)
Terry Graedon
Generally speaking, aspirin reduces the risk of stroke:
https://www.peoplespharmacy.com/articles/how-to-lower-your-stroke-risk-with-aspirin
It may increase the risk of hemorrhagic stroke slightly, however.
To determine whether taking aspirin makes sense in your particular case, you will need guidance from a health care professional who knows your health history.
Richard
I assume this is a relative improvment. What is the absolute improvement? What about the bleeding that aspirin can cause? What increase is observed?
Terry Graedon
You are correct. Unfortunately, the authors provided only relative risk data, not absolute risk.
As you note, aspirin does increase the risk for bleeding. The researchers did not specify that risk.