Posted by Kate Murphy on March 7th, 2007
After reviewing existing evidence for use of aspirin and other non-steroidal anti-inflammatory drugs (NSAIDS) to prevent colorectal cancer, the US Preventive Services Task Force (USPSTF) has concluded that its harms outweigh its benefits.
The USPSTF assessment:
Overall, the USPSTF concluded that harms outweigh the benefits of aspirin and NSAID use for the prevention of colorectal cancer.
The recommendation applies to adults at average risk of colorectal cancer without symptoms, including those with a family history of colon or rectal cancer. It does not include people with familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (Lynch I or II), or a history of colorectal cancer or adenomatous polyps.
The Task Force did say that doctors should continue to discuss the use of low-dose aspirin to prevent coronary heart disease because there is evidence that aspirin does reduce deaths from heart disease.
Colorectal cancer is the third most
common cancer for both men and women and the second leading cause of cancer death. Most colorectal cancer begins with adenomas (polyps) in average risk people over the age of 50.
The USPSTF is an independent panel of experts in primary care and prevention that systematically reviews evidence and effectiveness for clinical preventive services and develops recommendations for the use of those interventions.
USPSTF found the following evidence of benefits of aspirin or NSAID use:
- Fair to good evidence that aspirin and NSAIDS taken in higher doses over longer periods of time reduce the incidence of adenomatous polyps.
- Good evidence that low-dose aspirin does not reduce incidence of colorectal cancer.
- Fair evidence that aspirin in higher doses than those used to prevent coronary artery disease and NSAIDS may be associated with a reduction in the incidence of colorectal cancer.
- Fair evidence that aspirin used over longer periods of time may be associated with lower incidence of colorectal cancer.
- Poor evidence that aspirin and NSAID use reduces death from colorectal cancer.
The panel also found evidence of harms of aspirin and NSAID use:
- Good evidence that aspirin increases the risk of gastrointestinal bleeding related to dosage.
- Fair evidence that aspirin increases the risk of a hemorrhagic stroke.
- Good evidence that NSAIDS increase the risk of gastrointestinal bleeding and kidney problems, particularly in the elderly.
- Good evidence that one type of NSAIDS — COX-2 inhibitors — increase the incidence of kidney problems.
- COX-2 inhibitors appear to be associated with increased risk for cardiovascular events.
- Overall there is good evidence for at least moderate harms associated with aspirin and NSAIDS.
More than 80 percent of colorectal cancers will arise from adenomas, which are very common in people over the age of 50. Thirty to fifty percent of adults over 50 will develop adenomas, but few of those polyps will progress to colorectal cancer. Risk of polyps and of colorectal cancer increases as people get older.
The Task Force emphasizes the importance of screening for colorectal cancer, regardless of aspirin or NSAID use. The USPSTF strongly recommends screening for all men and women over 50 for colorectal cancer.
SOURCE: Annals of Internal Medicine, March 6 2007, Volume 146,Issue 5, Pages 361-364.
WHAT THIS MEANS FOR PATIENTS AND THE COMMUNITY
Routine use of aspirin and NSAIDS is more harmful than beneficial in preventing colorectal cancer. It takes a higher dose of aspirin over a longer period of time to prevent the type of polyps that have the potential of turning into cancer. Doses high enough to prevent adenomatous polyps also carry a risk of gastrointestinal bleeding, stroke, and kidney problems. The elderly are especially at risk.
COX-2 inhibitors, such as Vioxx® and Celebrex®, increase the risk of kidney problems and appear to be associated with cardiovascular events.
The recommendations against routine aspirin or NSAID use do not apply to people with genetic conditions including FAP and hereditary non-polyposis colorectal cancer or to people with a history of polyps or colorectal cancer. These individuals should discuss the risk and benefits of aspirin or NSAID use with their doctors.
However, the recommendation does apply to people with a family history of colorectal cancer who do not have a known genetic mutation.