Association between Low-Dose Aspirin Use and Colorectal Cancer Incidence in Taiwan

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Association between Low-Dose Aspirin Use
and Colorectal Cancer Incidence in Taiwan
Hui-Min Diana Lin, MSc, Pareen Vora, MSc,
Montse Soriano-Gabarr MD, et al.

Question: What is the association between low-dose aspirin use and risk of colorectal cancer (CRC) in an East Asian population?

Findings: In this nested case-control study among 4,710504 participants in Taiwan, low-dose aspirin use was associated with 11% lower risk of CRC among those aged 40 years or older, regardless of duration of drug use. A 30% lower CRC risk was observed when low-dose aspirin was initiated between age 40 and 59 years.

Meaning In this study, low-dose aspirin use was associated with lower CRC risk, and this association was larger when use started before age 60 years.

Abstract: Importance: A Population-based East Asian data have corroborated reports from non-Asian settings on the association between low-dose aspirin and a lower risk of colorectal cancer (CRC).

Objective: To evaluate the association between duration and recency of low-dose aspirin use and CRC risk.

Design, Setting, and Participants: This nested case-control study included individuals who initiated aspirin use and matched individuals who did not use aspirin. Data were collected from Taiwan National Health Insurance and Taiwan Cancer Registry from 2000 through 2015. CRC cases were age- and sex-matched in a 1:4 ratio with individuals in a control group, identified from a cohort of individuals who used and did not use aspirin through risk-set sampling. Data analysis was conducted from June 2018 to July 2019.

Exposures: Low-dose aspirin use was defined as receiving less than 150 mg per day, whereas 100 mg/d was most commonly used. Based on duration of low-dose aspirin use between cohort entry (initiation date of low-dose aspirin for aspirin use group or randomly assigned date for those who did not use aspirin) and index date (CRC diagnosis date for individuals in the case group and the diagnosis date for the 4 corresponding matched individuals in the control group), the 3 following mutually exclusive exposure groups served as the basis for analysis: (1) long-term current low-dose aspirin use, (2) episodic low-dose aspirin use, and (3) no low-dose aspirin use (the reference group).

Main Outcomes and Measures: CRC risk among the 3 exposure groups.

Results: Among 4710504 individuals (2747830 [51.7%] men; median [interquartile range] age at cohort entry in initiator group, 61 [52-71] years; median [interquartile range] age at cohort entry in nonuse group, 59 [51-68] years), 79 095 CRC cases (1.7% of study cohort) were identified. Compared with no low-dose aspirin use, the adjusted odds ratio (OR) for long-term current low-dose aspirin use and CRC risk was 0.89 (95% CI, 0.85-0.93); for episodic use, 0.88 (95% CI, 0.86-0.89). Adjusted ORs of 0.69 (95% CI, 0.63-0.76) and 0.64 (95% CI, 0.61-0.67) were observed for long-term current use and episodic low-dose aspirin use within the sub-cohort of individuals who initiated low-dose aspirin between age 40 and 59 years.

Conclusions and Relevance: In this study, low-dose aspirin use was associated with 11% lower CRC risk in an East Asian population, and this association was larger when low-dose aspirin use started before age 60 years.

Ref: JAMA Net Open. 2020;3(11):e2026494. doi:10.1001/jamanetworkopen.2020.26494