Colon Cancer: Aspirin May Improve Survival in Some

By Salynn Boyles
WebMD Health News

Reviewed by Louise Chang, MD

Oct. 24, 2012 -- One of the oldest and cheapest drugs around may be highly effective against colon cancer, a new study shows.

Some of the most cutting-edge cancer therapies involve targeted treatments used in patients with specific gene mutations, but many cost thousands of dollars a month. Not so in this case.

Aspirin Improved Survival for Some

Aspirin use was linked to survival of colon cancer patients whose tumors had mutations in the PIK3CA gene, according to the study published in The New England Journal of Medicine.

Almost all patients with the mutations who took aspirin regularly were still alive five years after diagnosis, compared to just 3 out of 4 patients with the mutation who took aspirin infrequently or did not take it at all.

Between 15% and 20% of colorectal cancer patients have tumors that carry this specific mutation.

The study suggests that aspirin could dramatically extend the lives of many of these patients, but it also raises new doubts about aspirin's usefulness in the treatment of other patients.

"Aspirin appears to work to increase survival of colorectal cancer patients if the tumor has the PIK3CA mutation, but it does not work if the tumor does not have the mutation," says researcher Shuji Ogino, MD, PhD, of Boston's Dana-Farber Cancer Institute.

Aspirin Targets Cancer-Promoting Enzyme

Aspirin is often recommended to patients with colorectal cancer, but it has not been clear if all patients benefit from the treatment or just some.

Previous research suggests that aspirin inhibits PI3K, an enzyme that plays an important role in promoting cancer.

Ogino and colleagues speculated that aspirin could be specifically effective against tumors with mutations in the PIK3CA gene, and to test the theory they examined data from two large, nationwide health studies that included information on participants' aspirin use.

The researchers looked at 964 participants in the two studies who had colorectal cancer.

Patients with this mutation who reported regular use of aspirin following diagnosis had a 46% reduction in overall death and an 82% reduction in death specifically related to colorectal cancer, compared to patients with the mutation who did not use aspirin.

Aspirin use did not appear to affect survival among patients whose tumors did not have the mutation.

'21st Century Targeted Therapy'

Although Ogino cautions that the findings must be confirmed, he says aspirin could help extend the lives of as many as 1 in 5 patients with colorectal cancer.

In an editorial published with the study, Boris Pasche, MD, PhD, of the University of Alabama at Birmingham, noted that a drug that is already in just about everyone's medicine cabinets could be a game-changer.

"Aspirin may well become one of the oldest drugs to be used as a 21st-century targeted therapy," he writes. But he also notes that more research needs to be done to validate these preliminary findings.

Even though aspirin was not found to improve survival in patients in the study without the specific tumor mutation, Pasche says it is too soon to say that aspirin therapy does not benefit these patients.

"More research is needed to figure this out," he says. "But we can hypothesize that patients with this mutation are more likely to benefit from aspirin therapy than those who don't have it."


What are risk factors for developing colon cancer? See Answer

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SOURCES: Liao, X. The New England Journal of Medicine, Oct. 25, 2012. Shuji Ogino, MD, PhD, department of medical oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston. Boris Pasche, MD, PhD, division of hematology/oncology, University of Alabama at Birmingham. News release, Dana-Farber Cancer Center.

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