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Original Investigation
January 21, 2021

Aspirin Use and Risk of Colorectal Cancer Among Older Adults

Author Affiliations
  • 1Clinical and Translational Epidemiology Unit, Massachusetts General Hospital and Harvard Medical School, Boston
  • 2Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston
  • 3Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
  • 4Department of Biostatistics, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
  • 5Division of Public Health Sciences, Department of Surgery, Washington University School of Medicine, St Louis, Missouri
  • 6Alvin J. Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri
  • 7Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts
  • 8Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
  • 9Program in Molecular Pathological Epidemiology, Department of Pathology, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
  • 10Broad Institute of MIT and Harvard, Cambridge, Massachusetts
  • 11Cancer Immunology and Cancer Epidemiology Programs, Dana-Farber Harvard Cancer Center, Boston, Massachusetts
  • 12Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
  • 13Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
  • 14Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
JAMA Oncol. Published online January 21, 2021. doi:10.1001/jamaoncol.2020.7338
Key Points

Question  What is the association of aspirin use with the risk of colorectal cancer in older adults?

Findings  In this pooled analysis of 2 cohort studies with a total of 94 540 participants, regular use of aspirin at or after age 70 years was associated with a lower risk of colorectal cancer compared with nonregular use. However, this reduction in risk was evident only among individuals who initiated use at a younger age.

Meaning  These results suggest that the initiation of aspirin use at an older age for the sole purpose of primary prevention of colorectal cancer should be discouraged; however, the findings support recommendations to continue using aspirin if initiated at a younger age.

Abstract

Importance  Although aspirin is recommended for the prevention of colorectal cancer (CRC) among adults aged 50 to 59 years, recent data from a randomized clinical trial suggest a lack of benefit and even possible harm among older adults.

Objective  To examine the association between aspirin use and the risk of incident CRC among older adults.

Design, Setting, and Participants  A pooled analysis was conducted of 2 large US cohort studies, the Nurses’ Health Study (June 1, 1980–June 30, 2014) and Health Professionals Follow-up Study (January 1, 1986–January 31, 2014). A total of 94 540 participants aged 70 years or older were included and followed up to June 30, 2014, for women or January 31, 2014, for men. Participants with a diagnosis of any cancer, except nonmelanoma skin cancer, or inflammatory bowel disease were excluded. Statistical analyses were conducted from December 2019 to October 2020.

Main Outcomes and Measures  Cox proportional hazards models were used to calculate multivariable adjusted hazard ratios (HRs) and 95% CIs for incident CRC.

Results  Among the 94 540 participants (mean [SD] age, 76.4 [4.9] years for women, 77.7 [5.6] years for men; 67 223 women [71.1%]; 65 259 White women [97.1%], 24 915 White men [96.0%]) aged 70 years or older, 1431 incident cases of CRC were documented over 996 463 person-years of follow-up. After adjustment for other risk factors, regular use of aspirin was associated with a significantly lower risk of CRC at or after age 70 years compared with nonregular use (HR, 0.80; 95% CI, 0.72-0.90). However, the inverse association was evident only among aspirin users who initiated aspirin use before age 70 years (HR, 0.80; 95% CI, 0.67-0.95). In contrast, initiating aspirin use at or after 70 years was not significantly associated with a lower risk of CRC (HR, 0.92; 95% CI, 0.76-1.11).

Conclusions and Relevance  Initiating aspirin at an older age was not associated with a lower risk of CRC in this pooled analysis of 2 cohort studies. In contrast, those who used aspirin before age 70 years and continued into their 70s or later had a reduced risk of CRC.

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    1 Comment for this article
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    Aspirin use and risk of colorectal cancer among older adults
    Tomoyuki Kawada, MD | Nippon Medical School
    Guo et al. examine the effect of aspirin use on the incident colorectal cancer (CRC) among older adults, aged 70 years or older (1). The adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) of regular use of aspirin for incident CRC was 0.80 (0.72-0.90). The significance disappeared in adults who initiated aspirin use at or after 70 years. I present information about their study with special reference to duration of aspirin use and the risk of CRC.

    Bosetti et al. reviewed estimates of the CRC risk in relation to the duration of aspirin use (2). Relative risks (RRs)
    (95% CIs) of aspirin use for one year, 3 years, 5 years and 10 years were 0.96 (0.95-0.8), 0.89 (0.85-0.93), 0.81 (0.76-0.88), and 0.71 (0.630.80), respectively. Although RR increased over 10 years of aspirin use, decline of RR within 10 years was consistent with data by Guo et al., presenting advantage of preventing CRC in adults who initiated aspirin use before 70 years. Regular use of aspirin reduces the risk of colorectal cancers with overexpression of COX-2 (3), and further studies are needed regarding the risk reduction of CRC by aspirin by considering the use of duration and amount. Anyway, risk of bleeding and cancer progression by aspirin use among older adults should also be paid with caution (4,5).


    References
    1. Guo CG, Ma W, Drew DA, et al. Aspirin use and risk of colorectal cancer among older adults. JAMA Oncol 2021 doi: 10.1001/jamaoncol.2020.7338. Epub ahead of print
    2. Bosetti C, Santucci C, Gallus S, et al. Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019. Ann Oncol 2020;31(5):558-568.
    3. Chan AT, Ogino S, Fuchs CS. Aspirin and the risk of colorectal cancer in relation to the expression of COX-2. N Engl J Med 2007;356(21):2131-2142.
    4. Perisetti A, Goyal H, Tharian B, et al. Aspirin for prevention of colorectal cancer in the elderly: friend or foe? Ann Gastroenterol 2021;34(1):1-11.
    5. McNeil JJ, Gibbs P, Orchard SG, et al. Effect of aspirin on cancer incidence and mortality in older adults. J Natl Cancer Inst 2020 doi: 10.1093/jnci/djaa114. Epub ahead of print
    CONFLICT OF INTEREST: None Reported
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