Fri Aug 26, 2005 7:41 pm   Reply with quote      

Women who took two or more doses of ASA or other non-steroidal anti-inflammatory drugs per week significantly reduced their risk of colorectal cancer — but also boosted the danger of internal bleeding, a major study has found.

The study of more than 80,000 women found that those who swallowed 14 or more tablets of ASA or other non-steroidal anti-inflammatory drugs (NSAIDs) a week on a consistent basis over 10 years had the lowest risk for developing colorectal cancer, said lead author Dr. Andrew Chan.

“What that suggests is that women who used Aspirin at the highest doses had approximately a 30 to 35 per cent reduction in risk compared with women who used no Aspirin,” Dr. Chan, a specialist in gastroenterology at Massachusetts General Hospital, said Tuesday from Boston.

A subset of women in the study who used the highest dose of the drugs consistently over 10 years cut their risk of colon cancer by more than half, he said.

But as effective as these anti-inflammatory painkillers appear to be in preventing bowel cancer, they don’t come without a cost.

High doses of ASA and other NSAIDs ratchet up the danger of gastrointestinal bleeding, a potentially life-threatening condition if left untreated. The drugs can irritate the lining of the upper digestive system, causing ulcers that eventually bleed.

Aspirin is a brand-name product in Canada which contains acetylsalicylic acid, or ASA. Other NSAIDs include ibuprofen, such as Advil or Motrin, and naproxin.

“When you want to consider that kind of treatment course, you want to think about that carefully with a doctor because it does potentially lead to a greater incidence of side-effects,” Dr. Chan acknowledged.

That’s why women should not start taking ASA or other NSAIDs in a bid to ward off colorectal cancer, said Dr. Linda Rabeneck, head of gastroenterology at Toronto’s Sunnybrook and Women’s Health Sciences Centre.

“We wouldn’t counsel women to take two Aspirin tablets a day for 20 years and then think that they didn’t need to be screened for colon cancer,” Dr. Rabeneck said. “This does not take the place of screening because not every woman can take Aspirin and because you have to take it for at least 10 years to get this effect.

“And it’s not a complete prevention of colon cancer. It’s a reduction in the chance of developing colon cancer.”

Still, Dr. Rabeneck said the study has added to mounting evidence suggesting that these garden-variety drugs do play a role in blocking tumour development in the large intestine.

“This had been a controversial, contentious, unsettled issue in the past and I think that this is an important study that really answers the question,” she said.

Much of the contention surrounded drugs like Vioxx and Celebrex, which are known as Cox-2 inhibitors. Studies suggested that this class of drug might cut the risk of colon cancer without the adverse gastrointestinal effects.

But those investigations hit a wall after it was discovered that Cox-2s raised the risk of cardiovascular events like heart attack and stroke. The revelation seemed to taint research into all anti-inflammatories, leading to questions about their benefit versus safety in cancer prevention.

That’s why the new findings are so exciting, said Dr. Chan, explaining that they support the principle that ASA and NSAIDs do somehow interfere with the mechanism underlying colorectal cancer.

This confirmation may direct researchers down other avenues that could lead to “therapies that may have as much benefit as Aspirin, or more benefit, but with fewer side-effects,” he said.

Dr. David McLean, chief of prevention programs for the B.C. Cancer Agency, agreed the “very powerful” study reinforces medicine’s understanding of how cancer arises in the colon.

“And that is that chronic inflammation is needed in many cases to develop that cancer, and by preventing that chronic inflammatory response, one reduces the cancer risk,” Dr. McLean said from Vancouver.

“Secondly, it is a point of cheer for those who must take high-dose Aspirin for other reasons, such as their arthritis. For them it is an added benefit.”

Dr. Chan and his research team analyzed data from the U.S. Nurses Health Study, which has been collecting health information from almost 83,000 women every two years since 1980. The analysis looked at data up until 2000.

Controlling for other risk factors for colon cancer, such as obesity, smoking and diet, the researchers found that 962 of the women had developed colon cancer — 607 of them did not use ASA or other NSAIDs on a regular basis compared with 355 who did.

Many of the women in the study who were taking ASA, especially at the highest doses, were taking it for pain relief, primarily musculoskeletal pain and headaches, said Dr. Chan, whose study appears Wednesday in the Journal of the American Medical Association.

Dr. Chan said previous studies have suggested that these drugs have a similar preventive effect in men.

Almost 20,000 Canadians will be diagnosed this year with colorectal cancer and it will kill an estimated 8,400, making it the third leading cause of cancer death for both men and women.

Doctors advise that anyone over age 50, even with no family history of colorectal cancer, should undergo regular screening for the disease.

Aaron

Fri Aug 26, 2005 8:23 pm   Reply with quote      

Generally speaking, pretty much all drugs have some kind of side effect. We need to find other ways to prevent diseases.