This article is more than 5 years old. Information may no longer be current.
Regular aspirin use reduces risk for gastrointestinal tract tumors
Click Here to Manage Email Alerts
Long-term use of low-dose aspirin significantly reduced risk for overall cancer, especially gastrointestinal tract cancers, according to the results of two prospective cohort studies.
Regular aspirin use appeared to offer particular protection from a substantial portion of colorectal cancers, even among individuals who underwent regular screenings, results showed.
“We can now recommend that many individuals consider taking aspirin to reduce their risk for colorectal cancer — particularly those with other reasons for regular use, such as heart disease prevention — but we are not at a point where we can make a general recommendation for overall cancer prevention,” Andrew T. Chan, MD, MPH, associate professor of medicine at Harvard Medical School and program director of the gastroenterology training program at Massachusetts General Hospital, said in a press release. “Our findings imply that aspirin use would be expected to prevent a significant number of colorectal cancers above and beyond those that would be prevented by screening and may have even greater benefit in settings in which the resources to devote to screening are lacking.”
Andrew T. Chan, MD, MPH
In 2015, the U.S. Preventive Services Task Force issued a draft recommendation supporting aspirin use to prevent colorectal cancer and cardiovascular disease. However, the population-wide effect of aspirin use on cancer — particularly within the context of cancer screening — had been undetermined, according to study background.
Thus, Chan and colleagues sought to define the potential benefits of aspirin use for overall and disease-specific cancer prevention, and to estimate the absolute benefit of aspirin within the context of screening.
To do so, they accessed data from two large U.S. prospective cohort studies of health care professionals: the Nurses’ Health Study (conducted between 1980 and 2010) and the Health Professionals Follow-Up Study (conducted between 1986 and 2012).
These studies followed 135,965 health care professionals (women, n = 88,084; men, n = 47,881) who biennially reported aspirin use. Women were aged between 30 years and 55 years at time of enrollment, and men were aged 40 years to 75 years at enrollment.
Follow-up extended up to 32 years.
The RRs for incident cancers served as a main outcome measure. Researchers also calculated the population-attributable risk, or the proportion of cancers attributable to aspirin use, to estimate the potential population-level effect of aspirin use on reducing cancer burden.
Researchers defined regular aspirin use as taking standard or low-dose aspirin at least two times per week, and nonregular users were considered those who used aspirin fewer than two times per week, or who did not use aspirin at all.
During the course of follow-up, the researchers observed 20,414 cancers among women and 7,571 cancers among men.
Regular use of aspirin appeared associated with a lower overall risk for cancer compared with nonregular use (RR = 0.97; 95% CI, 0.94-0.99). The researchers acknowledged that the reduction was largely attributable to a lower incidence of GI tract cancers (RR = 0.85; 95% CI, 0.8-0.91), especially colorectal cancer (RR = 0.81; 95% CI, 0.75-0.88).
The benefits of aspirin appeared dose dependent, with the benefit for GI tract cancers appearing with use of 0.5 to 1.5 aspirin tablets per week for at least 6 years.
Eduardo Vilar, MD
Further, among participants aged older than 50 years, regular aspirin use prevented 33 colorectal cancers per 100,000 person-years (population-attributable risk, 17%) among those who did not undergo a lower endoscopy.
The rate of prevention among participants who underwent lower endoscopy was 18 colorectal cancers per 100,000 person-years (population-attributable risk, 8.5%).
The researchers did not observe a protective link between aspirin use and the risk for other cancers, including breast cancer (age-adjusted RR = 1; 95% CI, 0.96-1.05), prostate cancer (age-adjusted RR = 0.98; 95% CI, 0.86-1.11) or lung cancer (age-adjusted RR = 1.08; 95% CI, 0.99-1.17).
The researchers acknowledged study limitations, including their inability to evaluate the effect of various aspirin doses on cancer risk. Further, they noted that because the study populations were largely non-Hispanic white, the findings may not be generalizable to other races.
“At this point, it would be very reasonable for individuals to discuss with their physicians the advisability of taking aspirin to prevent GI cancer, particularly if they have risk factors such as a family history,” Chan said. “But this should be done with the caveat that patients be well informed about the potential side effects of regular aspirin treatment and continue their regular screening tests. Furthermore, aspirin should not be viewed as a substitute for colonoscopy or other cancer screening tests.”
The study conducted by Chan and colleagues does not adequately assess the potential harms associated with long-term aspirin use, according to Eduardo Vilar, MD, Karen Colbert Maresso, MPH, and Ernest T. Hawk, MD, MPH, all of the department of cancer prevention and population sciences at The University of Texas MD Anderson Cancer Center, who wrote an accompanying editorial.
“To reflect accurately the often complex, real-world clinical scenarios in which physicians and patients contemplate the use of aspirin, any truly informative analysis of its use must weigh its cumulative benefits against its cumulative risks,” Vilar and colleagues wrote. “Few studies are capable of such an assessment, but two ongoing randomized clinical trials of aspirin in older patient populations should provide important additional detail on all of these points. For now, learning that aspirin’s preventive effects of GI tract cancer seem to extend even to those individuals who undergo colorectal cancer screening provides further support for aspirin’s possible future use as a cancer-preventive agent.” – by Cameron Kelsall
Disclosure: Chan reports consultant roles with Bayer Healthcare, Pfizer and Pozen Inc. The other researchers report no relevant financial disclosures. Vilar, Maresso and Hawk report no relevant financial disclosures.
Click Here to Manage Email Alerts