⇐ cover image courtesy of Wikimedia Commons/Attachment to the article: Aspirin found to reduce overall cancer risk/ Harvard gazette
caption: New research, published in JAMA Oncology, suggests that the use of aspirin may complement, but not replace, the preventive benefits of colonoscopy and other methods of cancer screening, according to the study authors.
Preventive effect most apparent against colorectal, other gastrointestinal tumors
An analysis of data from two major, long-term epidemiologic studies finds that the regular use of aspirin significantly reduces the overall risk of cancer, a reduction that primarily reflects a lower risk of colorectal cancer and other tumors of the gastrointestinal tract. The findings published Online First in JAMA Oncology suggest that the use of aspirin may complement, but not replace, the preventive benefits of colonoscopy and other methods of cancer screening.
“We now can recommend that many individuals consider taking aspirin to reduce their risk of 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,”
says Andrew Chan, MD, MPH, chief of the Clinical and Translational EpidemiologyUnit in the Massachusetts General Hospital (MGH) Division of Gastroenterology, the senior and corresponding author of the report.
“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 cancer screening are lacking.”
A large number of studies have supported the ability of regular aspirin use to prevent colorectal cancer, but aspirin’s effects on overall cancer risk has not been clear. To investigate that question, the research team analyzed 32 years worth of data from almost 136,000 participants in the Nurses’ Health Study and the Health Professionals Follow-up Study. They found that participants who reported regular aspirin use – defined as taking either a standard or a low-dose aspirin tablet at least twice a week – had a 3 percent absolute lower risk of any type of cancer than did those not reporting regular aspirin use. Regular aspirin use reduced the risk of colorectal cancer by 19 percent and the risk of any gastrointestinal cancer by 15 percent. No reduction was seen in the risk of breast, prostate or lung cancer.
Aspirin’s protective benefit appeared after five years of continuous use at dosages ranging from 0.5 to 1.5 standard tablets a week or one low-dose tablet a day. The researchers estimate that regular aspirin use could prevent close to 30,000 gastrointestinal tract tumors in the U.S. each year and could prevent an additional 7,500 colorectal tumors among U.S. adults over 50 who have endoscopic screening and 9,800 among the almost 30 million who are not screened. The benefit related to other gastrointestinal tumors appeared after six years and at the same dosage level – equivalent to a daily low-dose tablet – used to prevent cardiovascular disease.
“At this point, it would be very reasonable for individuals to discuss with their physicians the advisability of taking aspirin to prevent gastrointestinal cancer, particularly if they have risk factors such as a family history,”
says Chan, an associate professor of Medicine at Harvard Medical School.
“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.”
Yin Cao, MPH, ScD, Clinical and Translational Epidemiology Unit, MGH Gastroenterology, is the lead author of the JAMA Oncology paper. Additional co-authors are Reiko Nishihara, PhD, Shuji Ogino, MD, PhD, and Charles Fuchs, MD, MPH, Dana-Farber Cancer Institute; and Kana Wu, MD, PhD, Molin Wang, PhD, Walter Willett, MD, DrPH, Donna Spiegelman, ScD, and Edward Giovannucci, MD, ScD, Harvard T.H. Chan School of Public Health. The study was supported by a large number of National Institutes of Health grants.
Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $800 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, reproductive biology, systems biology, transplantation biology and photomedicine. In July 2015, MGH returned into the number one spot on the 2015-16 U.S. News & World Report list of «America’s Best Hospitals.»
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- Reference paper (open access)
Population-wide Impact of Long-term Use of Aspirin and the Risk for Cancer
JAMA Oncol. Published online March 03, 2016. doi:10.1001/jamaoncol.2015.6396
Importance The US Preventive Services Task Force recently recommended the use of aspirin to prevent colorectal cancer and cardiovascular disease among many US adults. However, the association of aspirin use with the risk for other cancer types and the potential population-wide effect of aspirin use on cancer, particularly within the context of screening, remain uncertain.
Objectives To examine the potential benefits of aspirin use for overall and subtype-specific cancer prevention at a range of doses and durations of use and to estimate the absolute benefit of aspirin in the context of screening.
Design, Setting, and Participants Two large US prospective cohort studies, the Nurses’ Health Study (1980-2010) and Health Professionals Follow-up Study (1986-2012), followed up 135 965 health care professionals (88 084 women and 47 881 men, respectively) who reported on aspirin use biennially. The women were aged 30 to 55 years at enrollment in 1976; the men, aged 40 to 75 years in 1986. Final follow-up was completed on June 30, 2012, for the Nurses’ Health Study cohort and January 31, 2010, for the Health Professionals Follow-up Study cohort, and data were accessed from September 15, 2014, to December 17, 2015.
Main Outcomes and Measures Relative risks (RRs) for incident cancers and population-attributable risk (PAR).
Results Among the 88 084 women and 47 881 men who underwent follow-up for as long as 32 years, 20 414 cancers among women and 7571 cancers among men were documented. Compared with nonregular use, regular aspirin use was associated with a lower risk for overall cancer (RR, 0.97; 95% CI, 0.94-0.99), which was primarily owing to a lower incidence of gastrointestinal tract cancers (RR, 0.85; 95% CI, 0.80-0.91), especially colorectal cancers (RR, 0.81; 95% CI, 0.75-0.88). The benefit of aspirin on gastrointestinal tract cancers appeared evident with the use of at least 0.5 to 1.5 standard aspirin tablets per week; the minimum duration of regular use associated with a lower risk was 6 years. Among individuals older than 50 years, regular aspirin use could prevent 33 colorectal cancers per 100 000 person-years (PAR, 17.0%) among those who had not undergone a lower endoscopy and 18 colorectal cancers per 100 000 person-years (PAR, 8.5%) among those who had. Regular aspirin use was not associated with the risk for breast, advanced prostate, or lung cancer.
Conclusions and Relevance Long-term aspirin use was associated with a modest but significantly reduced risk for overall cancer, especially gastrointestinal tract tumors. Regular aspirin use may prevent a substantial proportion of colorectal cancers and complement the benefits of screening.
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