Interesting Results In Study on Cancer Prevention with Aspirin



A daily dose of aspirin may reduce cancer risk, but it is no silver bullet.

Ever since the Salk vaccine eliminated polio, we have loved the idea of silver bullets to stop diseases. When consumer media announces a new study that might somehow diminish the effects of the largest modern-day fears — think cancer, heart disease, Alzheimer’s disease and HIV — the headlines almost always overreach. In truth, it’s rare for a drug, a single nutrient, or simple behavior to have that much of an impact.

In a similar vein, when hair loss treatments minoxidil (Rogaine) and finasteride (Propecia) were introduced, they were originally heralded as the cure for hair loss. Both work to a certain extent but incompletely for some and not at all for others.

This yearning for simple solutions was only reinforced in late 2010 by a metastudy published in The Lancet, the leading British medical journal. The studies were independently conducted over a period of four or more years and were originally designed to look at noncancer health conditions such as heart disease. But because each study also collected data on study participants’ other health factors, incidences of cancers were part of the data as well.

Collectively, the results of this metastudy raised intriguing results. Of the 25,570 people in all eight of the research programs, 674 participants died of cancer. Among the study participants who took aspirin, the death rate was a bit lower — 10.2 percent versus 11.1 percent among those participants who didn’t take aspirin on a daily basis.

That degree of drop was measured across shorter years (4) and longer years (20-plus) of aspirin use. The metastudy authors then sliced through the numbers to see if there was a greater effect from longer-term aspirin use. In fact, there was. The risk of dying from cancer dropped by 3.49 percent if the individual took a daily dose of aspirin for 20 or more years. For individuals who were over the age of 65, that risk level dropped by more than 7 percent.

How aspirin might — and might not — work at blocking cancer

Certain cancers seemed to be most affected by aspirin: digestive system tumors (esophageal, bowel and colorectal), lung cancer and prostate cancer. Pancreatic and brain cancer rates also seemed to be reduced. But note: The type of lung cancer associated with tobacco smoking was not affected by aspirin.

There is hope in this study. And it coincides with widely advertised recommendations for persons at risk of heart disease to take aspirin on a daily basis as well. Aspirin looks to be a twofer: one pill per day, two problems solved. Right?
It helps, of course, to understand how aspirin works. The primary function of acetylsalicylic acid (aspirin’s scientific name) is to deactivate the enzyme associated with inflammation, and inflammation is associated with many cancers and a host of other health problems. Some clear examples of the inflammation-cancer connection are hepatitis and liver cancer and chronic inflammatory bowel disease and colorectal cancer.

Unfortunately, just as with misreported cures for other diseases and conditions, media reporting on the metastudy also risks promising something that might not be there. Indiscriminate use of aspirin can have adverse side effects, such as gastrointestinal bleeding, hemorrhagic stroke, allergic reactions, hearing loss and tinnitus (ringing in the ears). Additionally, anyone taking aspirin regularly is advised to limit alcohol intake to one or two drinks a day. In other words, anyone who thinks about starting a daily dose regimen should seriously consider these potential adverse consequences.

But David Katz, M.D., director and co-founder of the Yale Prevention Research Center and a medical journalist, takes issue with the idea of universal cancer prevention through aspirin on several points. The metastudy was not able to look at adverse reactions in study subjects because the studies were on something else (heart disease). Therefore, such things as the incidence of gastrointestinal bleeding, a fairly common side effect, were not documented and consequently are unknown. But from other studies that look at such bleeding, its incidence is higher than the cancer rate reduction.

The real ways to reduce cancer risk

The rate of cancer reduction in the metastudy is not as significant as it appears, explains Dr. Katz. For example, the probability of not getting colorectal cancer among study participants went from 97 to 98 percent, which amounts to less than a 1 percent reduced risk. Instead, he cites other lifestyle choices, “other ways to reduce cancer risk that are known to have even greater benefits along with less risk [of side effects].” He advocates for four familiar preventive health habits:

  • Exercising
  • Abstinence from smoking
  • Managing weight *
  • Eating nutritiously *

Dr. Katz says that together these factors can account for a 60 percent reduction in overall cancer risk. “The side effects,” he notes, “are better overall health.”
As an example, a Washington University study released at the end of 2010 (Kathleen Y. Wolin, ScD, “Change in Physical Activity and Colon Cancer Incidence and Mortality,” Cancer Epidemiology, Biomarkers & Prevention 19, no. 12 [December 2010]: 3000-3004) found that of 150,000 men and women studied, those who exercised consistently for ten or more years had the lowest risk of colon cancer death.

Dr. Katz still allows that some people will benefit from a daily regimen of aspirin, usually in a 75 mg. dosage. “If you have risk factors for, or a family history of, gastrointestinal cancers, likely benefits of aspirin for this purpose might well outweigh the risks,” he says, adding “you should discuss this with your doctor.”

*Managing weight and eating nutritiously are not necessarily the same thing, as in the case of the individual who goes on draconian diets without regard for balance, variety and moderation.