Colorectal cancer (CRC) is the second leading cause of cancer death in the United States. There is compelling evidence that screening for CRC Finding and removing precancerous polyps early can reduce CRC mortality. However, screening has associated harms, including procedural complications and inherent limitations. For example, colonoscopy, the most common screening tool in the United States, is less effective in preventing cancers of the right or ascending side of the colon than cancers of the left or descending side of the colon.
In addition, only 60% of American adults recommended for screening follow it. Even under the best of circumstances, screening is resource-intensive, requires time, equipment, and a qualified physician to perform the procedure, and cannot be widely implemented in many parts of the world. Thus, alternatives to screening to effectively prevent CRC constitute an unmet need.
What are the alternatives to screening for the prevention of colorectal cancer?
Adhering to healthy lifestyle habits, including maintaining a healthy body weight, maintaining physical activity, and abstaining from smoking, can reduce the risk of CRC in all individuals. These habits also help prevent other chronic health problems.
In addition to lifestyle, chemoprevention – the use of agents to inhibit, delay or intercept and reverse cancer formation – also shows great promise. The ideal chemopreventive agent, or combination of agents, requires that the benefits outweigh the risks, especially since effective prevention probably requires long-term use. Many different agents have been proposed and studied over the past decades.
Study suggests aspirin may help prevent colorectal cancer
In an article published in the journal Intestine, the researchers conducted a systematic review, analyzing data from 80 meta-analyzes or systematic reviews of interventional and observational studies published between 1980 and 2019, examining the use of drugs, vitamins, supplements and dietary factors for prevention of CRC in people at medium risk.
The authors found that regular use of aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) or naproxen (Aleve), magnesium and folate is associated with a decrease in of CCR risk. Additionally, a high intake of fiber, fruits and vegetables, and dairy products also appear to be associated with reduced risk. In contrast, heavy alcohol consumption and heavy consumption of red or processed meat are associated with an increased incidence of CRC. There was no evidence of a protective benefit for tea, coffee, garlic, fish, or soy products.
The strongest level of evidence of a protective benefit exists for aspirin, which includes “gold standard” randomized controlled trials showing that regular use of aspirin reduces the risk of precancerous adenomatous polyps of the colon, a precursor of the vast majority of CCRs. The level of evidence is low to very low for other protective agents, including NSAIDs, magnesium and folate.
Limitations of this review include variation in included study populations, study designs, dosage of study agent (s), and duration of exposure and follow-up time. This reflects the challenges inherent in conducting studies of preventive agents for CRC, which require large numbers of participants and long-term follow-up (it takes several years for normal colon tissue to turn into polyp and then into CRC. ).
What should I tell my patients?
Despite a low level of supporting evidence, efforts to prevent cancer through dietary interventions, such as eating a high-fiber diet and reducing red meat consumption, are reasonable to recommend in general because they are generally not associated with negative consequences.
However, interventions that involve medication generally require a higher level of evidence, as they are associated with the potential for adverse effects. Of the drugs proposed for the chemoprevention of CRC, I believe aspirin has perhaps the strongest level of evidence to support potential efficacy, a conclusion shared by the review. The studies included in this systematic review conducted the US Task Force on Preventive Services (USPSTF) to recommend low-dose aspirin (81 milligrams per day) for the joint prevention of CRC and cardiovascular disease (CVD), for people aged 50 to 59 years with a 10% risk over 10 years for a CVD event. However, the USPSTF has warned of the potential harmful effects of aspirin, including gastrointestinal bleeding.
I generally recommend the use of aspirin for the prevention of CRC only after a detailed discussion of the potential risks and benefits, while acknowledging the lack of broader population-based recommendations or conclusive data supporting use in additional age groups or based on other risk factors.
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