Getty Images stock

Women who take a regular dose of aspirin may get a side benefit – a reduction in their risk of melanoma, a new study suggests. 

And the more years women take the over-the-counter-medication, the lower the risk, according to the study which was published online today in Cancer.

“We think our results are very exciting and that they add to the growing body of evidence suggesting that aspirin may have some real anti-tumor and anti-cancer properties,” said study co-author Jean Tang, an assistant professor of dermatology at Stanford University.

Tang and her colleagues scrutinized data from 59,806 Caucasian women who were taking part of the Women’s Health Initiative study. The women, who were between 50 and 79 years old at WHI’s outset, were followed for an average of 12 years. The researchers chose to concentrate on Caucasian women because melanoma is much more common among them.

At the beginning of the study, the women were asked which medications they were taking, what they ate and what activities they participated in. 

The women in the asprin group took a dose of aspirin at least twice a week at baseline. When they were asked about aspirin use again three years later, 60-70 percent of the group were still taking it at least twice a week, Tang says.

Overall, women who used aspirin had a 21 percent lower risk of melanoma compared to those who eschewed the medication. The longer women used aspirin, the lower the rate of the potentially fatal skin cancer. So, those who had used aspirin for one to four years had an 11 percent reduction in risk, as compared to 30 percent among those taking aspirin for five or more years.

In their calculations, the researchers took into account numerous melanoma risk factors, including differences in pigmentation, tanning practices, sunscreen use.

The researchers don’t know how aspirin lowers melanoma risk, but they’ve got some theories.

“Aspirin reduces inflammation,” Tang said. “Cancer cells with a lot of inflammation grow more and are more aggressive." Tang added that cancer cells tend to produce in excess the very same substance that aspirin and other NSAIDs knock back. 

The researchers failed to find a reduction in risk with other NSAIDs, however.

The new study, coupled with earlier evidence, makes a good case for aspirin’s anti-cancer properties, experts said.

Still, the effect may not be strong enough to counter aspirin’s possible side effects for people who have been told they shouldn't take the medication, said Dr. Robert Stern, a professor of dermatology at Harvard Medical School and chief of dermatology at the Beth Israel Deaconess Hospital. Stern co-authored a study published in 2011 that also found that aspirin reduced melanoma risk by 50 percent.

But for those who are sitting on the fence as to whether they should take aspirin for prevention of heart disease, this new research might be enough to push them over the edge since the benefits would now potentially be two-fold.

“I think it is too early to tell women to change their behavior, unless they would be taking it for the cardiovascular benefit also,” said Dr. Jenny Kim, an associate professor of dermatology at the David Geffen School of Medicine at the University of California, Los Angeles. “Before we can recommend that patients start taking aspirin to prevent melanoma we need to have some randomized controlled trials.”

 Related:

Daily aspirin may protect against melanoma

 Colonoscopy isn't just for high-risk people

Aspirin, one of the world's oldest and cheapest drugs, has shown remarkable promise in treating colon cancer in people with mutations in a gene that's thought to play a role in the disease.

Among patients with the mutations, those who regularly took aspirin lived longer than those who didn't, a major study found. Five years after their cancers were diagnosed, 97 percent of the aspirin users were still alive versus 74 percent of those not taking the drug.

Dave Einsel / AP

Colon cancer patients with certain gene mutations who took regular aspirin lived longer than those who didn't take the pills, researchers found.

Aspirin seemed to make no difference in patients who did not have the mutations.

This sort of study can't prove that aspirin caused the better survival, and doctors say more research must confirm the findings before aspirin can be recommended more widely. The study wasn't designed to test aspirin; people were taking it on their own for various reasons.

Still, the results suggest that this simple medicine might be the cheapest gene-targeting therapy ever found for cancer. About one-sixth of all colon cancer patients have the mutated gene and might be helped by aspirin. And aspirin costs just pennies a day.

"It's exciting to think that something that's already in the medicine cabinet may really have an important effect" beyond relieving pain and helping to prevent heart attacks, said Dr. Andrew Chan of Massachusetts General Hospital. He and others from Harvard Medical School led the study, which appears in Thursday's New England Journal of Medicine.

Cancers of the colon or rectum are a leading cause of cancer deaths worldwide. More than 140,000 new cases and 51,000 deaths from them are expected this year in the United States.

Several studies suggest that aspirin may help fight cancer, especially colorectal tumors. It is often recommended for people who have colon cancer and others at high risk of developing it. But it's not advised for wider use, or for cancer prevention, because it can cause serious bleeding in the stomach and gut.

What has been lacking, doctors say, is a good way to tell which people might benefit the most, so aspirin's risks would be justified. Chan's study suggests a way to do that.

It involved 964 people diagnosed with various stages of colon cancer who were among nearly 175,000 participants in two health studies based at Harvard that began in the 1980s. Every two years, they filled out surveys on their health habits, including aspirin use.

Most had surgery for their cancer, and many also had chemotherapy. They gave tumor tissue samples that could be tested for gene activity. Researchers focused on one gene, PIK3CA, that is involved in a key pathway that fuels cancer's growth and spread. Aspirin seems to blunt that pathway, so the scientists looked at its use in relation to the gene.

In those whose tumors had a mutation in that gene, regular aspirin use cut the risk of dying of colon cancer by 82 percent and of dying of any cause by 46 percent during the study period of about 13 years.

Only two of the 62 regular aspirin users whose tumors had the mutated gene died within five years of their cancer diagnosis versus 23 of 90 non-aspirin users with such a mutation.

The results are "quite exciting," said Dr. Boris Pasche, a cancer specialist at the University of Alabama at Birmingham who wrote an editorial that appears with the study in the medical journal. Half a dozen drugs are used to treat colon cancer, but only one meaningfully extends survival in people whose cancers have not widely spread, he said.

"Now we may have aspirin. That's why it's a big deal," Pasche said.

In the study, the dose of aspirin — baby or regular — didn't seem to matter, just whether any aspirin was regularly used.

The test for the gene is not expensive and is simple enough that most cancer centers should be able to do it, Chan and Pasche said.

The National Institutes of Health and several foundations paid for the study. One of the 17 authors consults for Bayer, a leading aspirin maker. Pasche has been a paid speaker for two companies that make cancer treatments and has two patent applications under review related to cancer treatment.

Researchers warn that aspirin may not be responsible for the improved survival seen in this study. Differences in how the patients' cancer was treated could have played a role.

For that reason, they say the next step should be a study where some people with the mutated gene are given aspirin and others are not, so their cancer outcomes can be compared more directly.

One colon cancer patient, L. Stewart Keefe, 60, a retired interior decorator and painter from Alton, N.H., decided several years ago to try it.

"I figured, what have I got to lose by taking some aspirin? It just seems like it was a simple enough thing to take," she said. "For me the bleeding risk is a very small possible consequence" compared with the risk of cancer coming back, she said.

More from NBCNews.com health: 

• Harvard hospital admits it promoted weak science on aspartame
• Fixing genes through cloning technique worth the ethical risk
• Hormone may cut Alzheimer's risk in menopausal women

By Rachael Rettner
MyHealthNewsDaily

Taking aspirin once a day may help prevent cancer, and perhaps even in some cases treat it, a growing body of research suggests.

A new study finds that people who took a low-dose aspirin daily for at least three years were 25 percent less likely to develop cancer than people who didn't take it.

Aspirin also reduced the risk of death from cancer by nearly 40 percent after five years, the researchers said.

The reduced risk of death may be due in part to a decrease in cancer's ability to spread to other organs. In a second study, researchers found a daily dose of aspirin led to a 36 percent reduction in the risk of being diagnosed with cancer that spread to other organs.

This suggests aspirin is likely "to be an effective additional treatment after the diagnosis of cancer," Dr. Peter Rothwell, one of the study's researchers and a neurologist at the University of Oxford in England, told MyHealthNewsDaily.

Taking a daily aspirin has been found to have a variety of health benefits, said Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in N.Y., including a reduced risk of heart attack and stroke.

However, more research is needed before aspirin can be recommended to reduce the risk of cancer. That's because the new study analyzed data from previous studies that were not designed to test the effect of aspirin on cancer prevention. "A study has to be specifically designed to prove a point," said Bernik, who was not involved in either new study.

People should speak with their doctors before deciding to take a daily aspirin, Bernik said.

Cancer prevention

Previous studies have found aspirin reduces the risk of death from cancer over the long term. However, the effect of aspirin on cancer in the short term, as well as its effect on developing cancer in the first place, was less clear.

Rothwell and colleagues analyzed data from 51 studies involving more than 77,000 people, in which about half of participants were randomly assigned to take a daily dose of aspirin.

There were fewer deaths among the people assigned to take a daily aspirin, compared with people who did not take aspirin (562 deaths versus 664 deaths).

In an analysis of six of the studies in which people took low doses of aspirin, there were three fewer cases of cancer yearly per 1,000 people in the aspirin group, compared with the group that did not take aspirin, but this effect did not show up until participants had taken aspirin for three years.

Side effects

Aspirin has side effects, including an increased risk of gastrointestinal bleeding. However, the researchers found that after about three years, the increased risk of major bleeding went away, as did aspirin's heart benefits. What was left was the reduced risk of cancer.

"For most individuals, the risk-benefit calculus of aspirin seems to favor aspirin’s long-term anti-cancer benefit," Drs. Andrew Chan and Nancy Cook, both of Brigham and Women’s Hospital in Boston, wrote in an editorial accompanying the study.

Because the findings are new, it will take time for researchers to decide whether guidelines should be changed to include a recommendation of aspirin for cancer prevention, said Eric Jacobs, strategic director of pharmacoepidemiology at the American Cancer Society. Such guidelines would have to take into account who is most likely to benefit from the recommendation, Jacobs said.

The study and editorial will be published tomorrow (March 21) in the journal the Lancet. The study had no funding and no input from drug companies, but the lead researcher has has been paid by several pharmaceutical companies for his work with them.

Related:

10 Do's and Don'ts to Reduce Your Risk of Cancer

7 Cancers You Can Ward Off with Exercise

Daily Dose of Aspirin May Reduce Colorectal Cancer Risk