MD, PhD, MAS
The US Preventive Services Task Force (USPSTF) has issued a draft guideline recommending the use of low-dose aspirin for the prevention of colorectal cancer (CRC) and cardiovascular disease (CVD) in adults aged 50 to 59 years, based on a growing body of long-term evidence demonstrating prevention and risk reduction benefits.
In the draft recommendation, the USPSTF issued a Grade B recommendation for low-dose aspirin in adults aged 50 to 59 years who are not at increased risk for bleeding and have a life expectancy of at least 10 years. For individuals aged 60-69, the agency issued a Grade C recommendation for preventive aspirin use. For this group, the decision to recommend aspirin to prevent CVD and CRC in higher-risk adults should be based on patient preferences and circumstances, and the practitioner’s professional judgment.
“Taking aspirin is easy, but deciding whether or not to take aspirin for prevention is complex,” USPSTF vice chair Kirsten Bibbins-Domingo, MD, PhD, MAS, said in a statement. “People aged 50 to 69 should talk with their doctor about their risk of cardiovascular disease and risk of bleeding, and discuss whether taking aspirin is right for them.”
The draft recommendation stipulates that individuals should be willing to take aspirin for at least 10 years, in order to realize the full benefits of the prophylactic measure. In a study with more than 20 years of follow-up that looked at aspirin use across 5139 individuals, the overall reduction in risk was 26% (HR, 0.74, P
= .02). However, those who took aspirin for more than 5 years saw a 63% reduction in risk (HR, 0.37; P
Subsequent studies found similar reductions in risk with aspirin at long-term follow-ups. In a pooled analysis of four clinical trials that assessed aspirin at varying doses compared with control, the absolute reduction in the risk of colon cancer was 24% at 20 years (HR, 0.78; P
= .02). In those who received aspirin for greater than 5 years, there was a 65% reduction in the risk of colon cancer (HR, 0.35; P
<.0001) and a 42% reduction in the risk of rectal cancer (HR, 0.58; P
“Each person has only one decision to make—whether or not to take aspirin for prevention,” USPSTF member Douglas K. Owens, MD, MS, said in a statement. “To help individuals and their clinicians make this decision, the Task Force integrated the evidence about the use of aspirin to prevent cardiovascular disease and colorectal cancer into one recommendation on the use of aspirin.”
In the CAPP2 trial, there was a 37% reduction in the risk of developing CRC with aspirin for Lynch syndrome carriers (HR, 0.63; 95% CI, 0.35-1.13; P
= .12). When taking several factors into consideration, the incidence rate ratio (IRR) was 0.56 (95% CI, 0.32-0.99; P
= .05). Patients who took aspirin for at least 2 years experienced a more dramatic reduction in CRC risk (n = 258). In these patients, there was a 59% reduction in risk (HR, 0.41; P
= .02) and an IRR of 0.37 (P
= .008) compared with placebo (n = 250).
“Before anyone begins to take aspirin on a regular basis they should consult their doctor as aspirin is known to bring with it a risk of stomach complaints, including ulcers,” said co-author John Burn, MD, professor of Clinical Genetics at Newcastle University, who led the international CAPP2 research collaboration. “We may be seeing a mechanism in humans whereby aspirin is encouraging genetically damaged stem cells to undergo programmed cell death, this would have an impact on cancer.”
At the present time, the USPSTF noted that there currently is insufficient evidence that low-dose aspirin use would be beneficial in preventing CVD and CRC in individuals aged <50 or ≥70 years. This draft recommendation is open for public comment until October 12, 2015. If it becomes a final recommendation statement, the USPSTF would be reversing its previous decision against the use of aspirin for CRC prevention. At this point, regular aspirin use for CRC and CVD prevention is listed as a Grade D recommendation.