Aspirin is a risky pill to swallow

The issue surrounding the use of aspirin for any so-called health protection is outweighed by the risks of silent bleeding and further for the risk of failure of the clotting mechanism in general, similar to long term warfarin therapy, and disruption of the cell wall membrane.

Herbs with "blood thinning" capacity without untoward effects are available, as is vitamin E. Both nutrient classes of natural supplements will aid in this effort.

Caution that high-dose aspirin is not recommended for routine long-term use in cancer prevention in a healthy population and carries the risk of gastrointestinal bleeding and other adverse effects.

Aspirin Prevents Colorectal Cancer but Risks Too High
By Crystal Phend, Staff Writer, MedPage Today
Published: January 24, 2008

BOSTON -- Long-term, higher-dose aspirin may protect men against colorectal cancer, but gastrointestinal and other associated risks outweigh the benefit, researchers said.

Men who took six to 14 aspirin tablets a week were 28% less likely than nonusers to develop colorectal cancer, and those who took more than 14 a week were at 70% lower risk, reported Andrew T. Chan, M.D., of Massachusetts General Hospital and Harvard, and colleagues, in the January issue of Gastroenterology.

However, the benefit was seen only for men who took aspirin consistently for at least six years, they found in their analysis of the Health Professionals Follow-Up Study.

Randomized controlled trials have shown reduced adenoma recurrence with short-term aspirin use, but the Physicians' Health Study and the Women's Health Study showed low-dose aspirin did not protect against colorectal cancer.

"Our study provides additional support that aspirin chemoprevention requires use of higher doses over a long period, which raises the risk of adverse events such as gastrointestinal bleeding," they said.

Thus, aspirin cannot be recommended for general chemoprevention for a healthy population, they said. That conclusion is consistent with those of the U.S. Preventive Services Task Force.

In an accompanying editorial, Peter Lance, M.D., of the Arizona Cancer Center in Tucson, agreed that the toxicity to achieve these benefits would be prohibitive.

"Despite much effort over two decades," he noted, "no chemopreventive intervention for colorectal cancer has yet entered routine clinical practice as part of usual care for healthy members of the general population."

The Health Professionals Follow-up Study followed 51,529 male dentists, optometrists, osteopaths, podiatrists, pharmacists, and veterinarians for 18 years with biennial questionnaires.

During this period, there were 975 documented cases of colorectal cancer.

Men who used at least two aspirin a week, classified as regular users, had lower risk of colorectal cancer overall than men who did not regularly take aspirin in multivariate analysis controlling for other colorectal cancer risk factors (relative risk 0.79, 95% confidence interval 0.69 to 0.90).

The benefit rose with increasing dose (P=0.004 for trend). Compared with men who did not report taking aspirin, the relative risk of colorectal cancer was:

Not reduced for those who took the equivalent of 0.5 to 1.5 standard tablets (325 mg) of aspirin a week (RR 0.94, 95% CI 0.75 to 1.18)
Reduced, but not significantly so, for men taking two to five tablets a week (RR 0.80, 95% CI 0.63 to 1.01)
Significantly reduced for men taking six to 14 standard aspirin tablets a week (RR 0.72, 95% CI 0.56 to 0.92)
Dramatically reduced for men who took more than 14 tablets a week (RR 0.30, 95% CI 0.11 to 0.81)
However, use conferred a benefit only for men who reported consistent use for more than five years (P=0.008 for trend).

Greater benefits for longer duration of use were seen for advanced-stage cancers (P=0.03 for stage 2 and P=0.005 for stage 3 and 4 for trend), but not for early-stage cancers (P=0.31 for trend).

When men discontinued regular aspirin use, the benefit fizzled out after four to five years and their relative risk of colorectal cancer was as if they had never taken it (RR 1.00, 95% CI 0.72 to 1.39).

The study may have underestimated duration of aspirin use, the researchers noted.

A previous subset study in the same Health Professionals Follow-up cohort found most aspirin users had used it for at least five years before baseline.

"Thus, it is likely that the minimum duration of use necessary to observe a risk reduction may be comparable to the 10 years we observed in a parallel cohort of women," Dr. Chan and colleagues said.

Nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) similarly improved colorectal cancer risk when used regularly for more than five years (RR 0.72, 95% CI 0.55 to 0.94, P=0.008 for trend with increasing duration).

However, no nonspecific analgesic effect appeared when the researchers looked at regular acetaminophen use for five or fewer years (RR 0.98, 95% CI 0.78 to 1.22) or longer than five years (RR 0.89, 95% CI 0.65 to 1.22).

The investigators noted that the study was observational and aspirin use was self-selected, but they countered that the results have "strong biologic plausibility" with causality demonstrated in prior studies.

Further study is needed to determine whether the benefits would outweigh the risks for a subset of patients, they concluded.

Other strategies may include finding new chemopreventive agents or combining lower doses of agents with separate pathways to improve safety, Dr. Lance added.

The study was supported by a grant from the National Cancer Institute and by the Entertainment Industry Foundation National Colorectal Cancer Research Alliance.

Dr. Chan reported receiving support from awards from the American Gastroenterological Association/Foundation and the National Cancer Institute, as well as an award from the Glaxo Institute for Digestive Health for an unrelated study.

Dr. Lance provided no information on conflicts of interest.

Additional source: Gastroenterology
Source reference:
Chan AT, et al "Aspirin dose and duration of use and risk of colorectal cancer in men"Gastroenterology 2008; 134: 21-28.

Additional source: Gastroenterology
Source reference:
Lance P, "Chemoprevention for colorectal cancer: some progress but a long way to go" Gastroenterology 2008; 134: 341-353.

Add Your Knowledge™

doug keller - Jan 25, 2008
I would like to see risk/benefit/cost analysis comparing chronic aspirin use to colonoscopy.

navarro jose, md - Jan 26, 2008
I know a patient that because arthritis took aspirin in a compulsive neurotic way and in spite of gastric pain and bleeding,continued to do it, until ultimately developed renal insufficiency.