527 Background: Aspirin, commonly used for prevention of cardiovascular and cerebrovascular diseases, is well-known to protect against colorectal cancer (CRC) development but increase risk of gastrointestinal bleeding (GIB). Few large-scale studies have compared the benefit and risk of long-term aspirin usage. This cohort study aims to evaluate the use of low-dose aspirin to prevent CRC and the risk of GIB associated with the aspirin use. Methods: A population-based clinical dataset was used to compare incidence and mortality of CRC and GIB patients receiving low-dose aspirin with sex-and-age matched controls (in 1:2 ratio). Patients with aspirin≤6 months were excluded. Clinical data of 206,243 aspirin users (mean dose 80 mg/day, mean duration 7.7 years) and 482,966 non-users were included. All patients must have at least 10-year follow up on clinical outcome. Results: Among aspirin users 5,776 (2.80%) were diagnosed with CRC; 2,097 (1.02%) died of the malignancy. 16,483 (3.41%) non-users were diagnosed with CRC; 7,963 (1.65%) died of CRC. Using the cox-proportional hazard regression, aspirin usage showed a modest but significant reduction in CRC mortality (HR = 0.65; 95% CI = 0.62 to 0.69). On the other hand, 11,187 (5.42%) aspirin users developed GIB, and 841 (0.41%) died. 15,186 (3.14%) non-users developed GIB, and 1,682 patients (0.35%) died. Aspirin users showed modest but significant increased risk of GIB-related mortality (HR = 1.24; 95% CI = 1.14 to 1.35). Conclusions: The long-term use of low dose aspirin shows preventive effect on CRC, but also increases the associated GIB risk. Considerations of prophylactic use of aspirin should balance the benefit and the risk of this treatment to the target population. [Table: see text]
The effect of low-dose aspirin on colorectal cancer prevention and gastrointestinal bleeding according to bodyweight and body mass index: Analysis of UK primary care data
