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Omega-3 Curbs Pre-Cancer Bowel Polyps in Trial
3/22/2010
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Small clinical trial finds omega-3 EPA as effective as the drug prescribed to prevent pre-cancerous bowel polyps, without its associated cardiovascular risks
by Craig Weatherby


People who took omega-3 fatty acids for six months enjoyed a significant reduction in the size and number of pre-cancerous bowel (polyps).

While this small pilot clinical trial involved people with a rare genetic susceptibility to bowel cancer, its authors suggest that omega-3s may help prevent “regular” bowel polyps. 

Key Points
  • Omega-3 EPA found as effective as drugs prescribed to prevent pre-cancerous bowel polyps.
  • Findings occurred in people with rare genetic condition that raises the risk of bowel polyps and cancer.
  • The authors found it plausible to presume that omega-3s could help prevent all bowel polyps.
  • Results need confirmation by larger clinical trials, but fit with lab and animal study data.
  • The anti-inflammatory prescription drug used for polyp prevention (Celebrex) raises patients’ gastric and heart risks.
The volunteers took supplements containing one of the two major omega-3s in fish fat, known as EPA.

EPA is the omega-3 that exerts a moderating influence on inflammation, which is believed to fuel bowel, colon, breast, and many other cancers.


The other omega-3 fat in fish, called DHA, displays its own anti-cancer effects in lab and animal tests.

UK trial finds omega-3 EPA about as good as Celebrex
A team of investigator from Britain’s University of Leeds recruited 55 patients diagnosed with a pre-cancerous condition called familial adenomatous polyposis or FAP.

All 55 patients had previously undergone surgery and were being monitored by use of a camera on the end of a flexible tube (endoscope).

Half of the patients were assigned to take 2 grams of EPA daily for six months, while the other half were given placebo (inactive) capsules.

The particular EPA supplement used contains about four times as much EPA as you’d get from eating two to three portions of fish a week.

(They did not test a lower dose, so it is possible that less EPA would yield significant results, with duration of the daily omega-3 regimen being a possible factor.)

The EPA capsules were “enteric coated” so they would release their contents further down the intestines than normal, mostly to help disguise their taste, and to prevent the revealing indigestion that a few people experience with fish oil supplements.

The scientists measured the number and size of polyps at the beginning and end of the end of the six month study, and the count revealed significant differences between the two groups of patients.

The number of polyps fell among those taking EPA capsules but rose in the placebo group, representing an advantage of almost 22.5 percent for the EPA group.

In addition, polyp size shrank in the EPA group but rose in the placebo group, representing an advantage of just under 30 percent for the EPA group.

The EPA capsules produced few side effects… no more than were reported by the placebo group.

The differences in polyp numbers and size were considered clinically significant, and compared favorably with the results seen with the standard prescription drug used for prevention (Celebrex).

Since omega-3s are safe and good for cardiovascular health, the UK team noted that EPA could be especially suitable for older patients at risk of both bowel cancer and heart disease.

However, DHA is equally heart-healthy and generally unfriendly to tumor growth, so it makes more sense to combine the two… which happens in fish fat and in standard fish oils, most of which provide EPA and DHA in roughly equal amounts.

Rare genetic profile provides good tool to test prevention prospects
About one in 12,000 people have the genetic make-up that predisposes them to FAP, which is believed responsible for about one in every 100 bowel cancers.

This rare susceptibility to bowel cancer is signaled by a family history of FAP, and genetic testing can confirm the risk.

Gene variants associated with FAP affect about one in 12,000 people, and by age 35 years, 95 percent of people with FAP have polyps.  Unless they are surgically removed, progression of the polyps to colon cancer is almost certain by about age 40.

Development of the pre-cancerous polyps may be largely a genetic matter, but their progression to cancer is fueled by chronic inflammation.

Because people with FPA invariably develop bowel polyps that progress to cancer, they make convenient subjects for studying ways to curb all cases of bowel cancer.

Aspirin and Celebrex: Double-edged cancer-curbers
Aspirin, ibuprofen (Advil), naproxen sodium (Aleve), and similar substances are called non-steroidal anti-inflammatory drugs (NSAIDs).

NSAIDs display anti-cancer properties in some contexts, probably because they reduce inflammation, which helps drive growth of many tumors.

NSAIDS can significantly decrease the number of bowel polyps, but still leave too many to be detected and removed.

Aspirin had been prescribed to prevent bowel cancer… but its proven harms (gastric bleeding and death) far outweigh its benefits for this purpose… and those serious adverse effects occur at doses just one-third of the effective cancer-curbing dose (USPSTF 2007).

When aspirin’s safety as a chronic bowel-cancer-defender came into question, doctors turned to Celebrex, a “COX-2 inhibitor” drug developed as an aspirin alternative.

It was thought that Celebrex and other COX-2 inhibiting drugs would be less risky than aspirin for chronic use, but that hope has proven false.

While Celebrex, Vioxx, and other COX-2 inhibitors produce somewhat less risk of gastric bleeding and related death, they replace that reduced danger with heightened cardiovascular risks.

(In 2004, Merck voluntarily withdrew Vioxx from the market because of concerns about increased risk of heart attack and stroke.)

Researchers have been seeking safer, comparably effective alternatives to aspirin and Celebrex, and the results of a small clinical trial suggest that fish fats may be able to help meet that need.

As Professor Mark Hull the lead author of the new study said, “There is definitely a clinical need for an effective, preventative therapy that is both safe and well tolerated as the existing drug therapy for FAP can be associated with an increased risk of heart attack in older individuals” (UL 2010).


Sources
  • British Medical Journal (BMJ). Omega 3 curbs precancerous growths in those prone to bowel cancer. March 17, 2010. Accessed at http://www.eurekalert.org/pub_releases/2010-03/bmj-o3c031710.php 
  • Campbell CL, Smyth S, Montalescot G, Steinhubl SR (2007). "Aspirin dose for the prevention of cardiovascular disease: a systematic review". JAMA 297 (18): 2018–24.
  • Flossmann E, Rothwell PM (May 2007). Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies". Lancet 369 (9573): 1603–13.
  • University of Leeds (UL). New omega-3 preparation protects against bowel polyps. March 18, 2010. Accessed at http://www.leeds.ac.uk/news/article/764/new_omega-3_preparation_protects_against_bowel_polyps 
  • U.S. Preventive Services Task Force (USPSTF). Routine aspirin or nonsteroidal anti-inflammatory drugs for the primary prevention of colorectal cancer: U.S. Preventive Services Task Force recommendation statement, March 2007. Ann. Intern. Med. 146 (5): 361-4.

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