Commentary: Low-Dose Aspirin for Prevention Colorectal Cancer: New USPSTF Recommendations
Aasma Shaukat, MD, MPH, FACG, University of Minnesota
Dr. Shaukat is the ACG Governor for Minnesota. She is the Section Chief, GI Section, Minneapolis VA Health Care System, an Associate Professor at the University of Minnesota, and a member of the Minnesota Evidence-based Practice Center.
Commentary on Albert L. Siu, MD, MSP, on behalf of the U.S. Preventive Services Task Force, “Aspirin Use for the Primary Prevention of Cardiovascular Disease and Colorectal Cancer: U.S. Preventive Services Task Force Recommendation Statement,” Annals of Internal Medicine published online, April 11, 2016
In Annals of Internal Medicine yesterday, the U.S. Preventive Services Task Force updated their recommendations from 2007 on use of low-dose aspirin for prevention of colorectal cancer. These new recommendations are quite a contrast to the old ones, and are based on several important new studies, along with results from a micro-simulation modeling study.
The important new recommendation is that for men and women 50 to 59 years old, who have a 10 percent or greater risk of developing cardiovascular disease over 10 years, and are not at increased risk for bleeding, should receive daily low-dose aspirin. This is a grade B recommendation, which means that there is moderate to high certainty that the benefits outweigh the harms, and that physicians should recommend it to their patients.
The simple message for patients between 50 and 59 that meet the criteria is: On average the benefit of taking daily low dose aspirin for prevention of colon cancer exceed the risks, and we recommend you take it.
For men and women between the ages of 60 to 69, the use of daily low-dose aspirin for prevention of CRC may be considered. However, this is a grade C recommendation, which means that the benefit versus harms ratio is much smaller, such it requires a discussion between the patient and the physician. The reason for the difference is that risk of GI hemorrhage is higher in this age group, and the benefit of aspirin for CRC prevention is smaller, than for 50 to 59 year olds.
The simple message for patients between the ages of 60 to 69 that meet the criteria is that it’s a close call, and they should discuss with their physician what might be best for them.
It is very important to understand that these recommendations apply to patients meeting certain criteria:
- First, the individual’s risk of cardiovascular event needs to be calculated (use the ACC/AHA risk calculator) and must be 10 percent or greater of having cardiovascular disease in the next 10 years.
- Second the individual should be at low risk for GI hemorrhage from daily aspirin use. There is no calculator for this, but the risk factors are: older age, male sex, regular use of NSAIDs, prior history of gastrointestinal hemorrhage, bleeding disorders, renal failure, severe liver disease and thrombocytopenia.
- Third, the individual must be willing to take aspirin for at least 10 years to see a benefit.
- Fourth, the individual must have a 10 year life expectancy, which is likely not an issue for most 50 to 59 year olds, but important for 60 to 69 year olds.
- Fifth, low dose aspirin (75 to 100 milligrams daily) should be used. Most convenient and readily available dose in the United States is 81 milligrams daily.
- And finally, this recommendations applies to adults at increased risk for primary cardiovascular disease (not secondary prevention), and those at average risk for colorectal cancer (i.e., no family history or personal history of colorectal cancer or familial adenomatous polyposis.)
The implementation of these recommendations is not straightforward, and requires an assessment by the physician of a patient’s risk for cardiovascular event in the next 10 years, their life expectancy, risk of gastrointestinal hemorrhage and adherence to aspirin for 10 years.
In current practice, 40 percent of patients over the age of 50 report taking aspirin for primary or secondary prevention of cardiovascular disease. Data from the CDC’s National Health and Nutrition Examination Survey suggests that among those eligible, 41 percent were taking the aspirin due to their doctor’s recommendation.
These new USPSTF recommendations underscore the importance of accurate patient assessment and well informed, shared decision making.
What do these recommendations mean for the gastroenterologist?
We are in the best position to assess a patient’s risk of colorectal cancer and gastrointestinal hemorrhage. It is important for GI physicians to understand these recommendations and especially their nuances, to apply them to our patients, and to help our primary care colleagues balance the benefit of aspirin for colorectal cancer prevention with the risk of GI hemorrhage.
Modelling Study Informs USPSTF Recommendations
The authors also performed a modelling study to inform these recommendations. To put the recommendations in context of numbers, if 1000 men between 50 and 59 years of age with a cardiovascular disease risk of 10 percent over the next 10 years took low-dose aspirin daily for the rest of their lives, there would be 22 non-fatal heart attacks and 14 new colon cancer cases prevented, but 28 individuals would have a serious GI bleeding event over a lifetime.
Putting these disparate health outcomes together into quality-adjusted life years, or QALYs, there would be a net gain of 58 QALYs for men. For women, the net gain in QALYs is 62. A QALY is a metric that assesses quality and quantity of additional life lived, and equates to number of years of perfect health gained.
If 1000 men between 60 and 69 years of age with a 10 percent risk of cardiovascular disease over 10 years take aspirin for life, there would be 16 non-fatal heart attacks prevented, 11 cases of colon cancer prevented, but 31 additional serious GI hemorrhage events caused. The QALYs gained is 18 for men, and 28 for women — a much smaller benefit than for younger individuals. This is because in this age group the life expectancy is shorter, there is higher risk of GI hemorrhage, and the benefit in colon cancer prevention is smaller due to the long latent period (10 to 20 years) required to see a benefit in colon cancer reduction with aspirin use.
Read the College’s Media Statement