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. 2013 Jul 16;159(2):77-85.
doi: 10.7326/0003-4819-159-2-201307160-00002.

Alternate-day, low-dose aspirin and cancer risk: long-term observational follow-up of a randomized trial

Nancy R Cook  1 , I-Min Lee, Shumin M Zhang, M Vinayaga Moorthy, Julie E Buring
Affiliations

Alternate-day, low-dose aspirin and cancer risk: long-term observational follow-up of a randomized trial

Nancy R Cook et al. Ann Intern Med. .

Abstract

Background: Recent evidence suggests that daily aspirin use decreases cancer risk, particularly for colorectal cancer, but evidence for alternate-day use is scant.

Objective: To examine the association between long-term, alternate-day, low-dose aspirin and cancer in healthy women.

Design: Observational follow-up of a randomized trial.

Setting: Female health professionals.

Participants: 39,876 women aged 45 years or older in the Women's Health Study (ClinicalTrials.gov: NCT00000479), 33 682 of whom continued observational follow-up.

Intervention: 100 mg of alternate-day aspirin or placebo through March 2004, with a median 10-year follow-up. Posttrial follow-up continued through March 2012.

Measurements: Cancer incidence.

Results: A total of 5071 cancer cases (including 2070 breast, 451 colorectal, and 431 lung cancer cases) and 1391 cancer deaths were confirmed. Over the entire follow-up, aspirin had no association with total (hazard ratio [HR], 0.97 [95% CI, 0.92 to 1.03]; P = 0.31), breast (HR, 0.98 [CI, 0.90 to 1.07]; P = 0.65), or lung (HR, 1.04 [CI, 0.86 to 1.26]; P = 0.67) cancer. Colorectal cancer was reduced in the aspirin group (HR, 0.80 [CI, 0.67 to 0.97]; P = 0.021), primarily for proximal colon cancer (HR, 0.73 [CI, 0.55 to 0.95]; P = 0.022). The difference emerged after 10 years, with a posttrial reduction of 42% (HR, 0.58 [CI, 0.42 to 0.80]; P < 0.001). There was no extended effect on cancer deaths or colorectal polyps. More gastrointestinal bleeding (HR, 1.14 [CI, 1.06 to 1.22]; P < 0.001) and peptic ulcers (HR, 1.17 [CI, 1.09 to 1.27]; P < 0.001) occurred in the aspirin group.

Limitations: Not all women received extended follow-up, and posttrial ascertainment bias cannot be ruled out. Gastrointestinal bleeding, peptic ulcers, and polyps were self-reported during extended follow-up.

Conclusion: Long-term use of alternate-day, low-dose aspirin may reduce risk for colorectal cancer in healthy women.

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Figures

Figure 1
Figure 1
Flow of participants through the Women’s Health Study including extended follow-up.
Figure 2
Figure 2
Cumulative incidence of A) total, B) breast, C) colorectal, and D) lung cancer from time of randomization by randomized aspirin assignment, with p-value from log-rank test.
Figure 3
Figure 3
Post-trial incidence of colorectal cancer by randomized aspirin and post-trial aspirin use A) unweighted and B) weighted by inverse propensity of aspirin use post-trial.
See this image and copyright information in PMC

Comment in

References

    1. Chan AT, Arber N, Burn J, et al. Aspirin in the chemoprevention of colorectal neoplasia: an overview. Cancer Prev Res (Phila) 2012;5(2):164–78. - PMC - PubMed
    1. Cuzick J, Otto F, Baron JA, et al. Aspirin and non-steroidal anti-inflammatory drugs for cancer prevention: an international consensus statement. Lancet Oncol. 2009;10(5):501–7. - PubMed
    1. Bosetti C, Rosato V, Gallus S, Cuzick J, La Vecchia C. Aspirin and cancer risk: a quantitative review to 2011. Ann Oncol. 2012;23(6):1403–15. - PubMed
    1. Cole BF, Logan RF, Halabi S, et al. Aspirin for the chemoprevention of colorectal adenomas: meta-analysis of the randomized trials. J Natl Cancer Inst. 2009;101(4):256–66. - PMC - PubMed
    1. Rothwell PM, Wilson M, Elwin CE, et al. Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials. Lancet. 2010;376(9754):1741–50. - PubMed

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