Low-dose aspirin prevents common GI cancers in Chinese adults without ASCVD

Low-dose aspirin reduces risks of some common gastrointestinal (GI) cancers, including colorectal cancer (CRC) and gastric cancer (GC), in Chinese without atherosclerotic cardiovascular disease (ASCVD), compared with paracetamol, the first population-wide study from the University of Hong Kong (HKU) has shown.

The study also showed an increased risk of gastrointestinal bleeding (GIB) among low-dose aspirin users, except in those <60 years of age or on gastroprotective agents, including proton-pump inhibitors and histamine-H2 receptor blockers. [BMJ Open 2022;12:e050510.]

Despite accumulated evidence of the reduced risk of GI cancers associated with low-dose aspirin, study results have been inconsistent and evidence from randomized controlled trials has been lacking. Also, the risk-benefit ratio for low-dose aspirin in GI cancer prevention may vary by ethnicity. “Considering the possible variation in the effect of low-dose aspirin on GI cancer, as well as in the risk of GIB, further studies conducted in Asian populations are warranted,” the researchers stated.

With electronic health records of the Hospital Authority’s Clinical Data Analysis and Reporting System (CDARS), the researchers compared 99,358 adults aged ≥40 years (mean age, 68.6 years; female, 48.4 percent) prescribed low-dose aspirin (n=49,679) or paracetamol (n=49,679), with a prescription start date between January 2004 and December 2008 using propensity score (PS) matching. Most low-dose aspirin users (72.2 percent) took a daily dose of 80 mg.

With a median follow-up of 10.0 years, 1,954 of all PS matched individuals developed CRC (low-dose aspirin, n=876; non-aspirin, n=1,078), 515 developed GC (low-dose aspirin, n=222; non-aspirin, n=293), and 206 developed oesophageal cancer (EC; low-dose aspirin, n=96; non-aspirin, n=110).

A significant association was found between low-dose aspirin use and lower risks of both CRC and GC (CRC: hazard ratio [HR], 0.83; 95 percent confidence interval [CI], 0.76 to 0.91) (GC: HR, 0.77; 95 percent CI, 0.65 to 0.92). Notably, low-dose aspirin was associated with not only a reduced risk of CRC among individuals aged 70–79 years (HR, 0.82; 95 percent CI, 0.71 to 0.94) but also a reduced risk of GC among those aged >80 years (HR, 0.60; 95 percent CI: 0.43 to 0.84). However, no significant association was found for EC (HR, 0.88; 95 percent CI, 0.67 to 1.16).

In terms of safety, GIB occurred in 10,629 individuals (low-dose aspirin, n=5,498; non-aspirin, n=5,131). The risk of GIB was significantly higher in low-dose aspirin users than non-aspirin users (HR, 1.15; 95 percent CI, 1.11 to 1.20). However, such association was not found among individuals 40–59 years of age (40–49 years: HR, 0.94; 95 percent CI, 0.77 to 1.15) (50–59 years: HR, 1.05; 95 percent CI, 0.93 to 1.19) or in those on gastroprotective agents (HR, 1.03, 95 percent CI, 0.96 to 1.10). Additionally, the rate of fatal GIB was comparable between low-dose aspirin users and non-aspirin users (1.6 percent for each).

“This information … could inform clinical decisions to initiate low-dose aspirin in Chinese adults without ASCVD who highly value preventing CRC and GC,” the researchers suggested.

The current findings were consistent with a pooled analysis of randomized trials that demonstrated a reduced risk of CRC in long-term aspirin users. [Lancet 2010;376:1741-1750]

Since aspirin is an affordable and easily accessible drug with a recognized pharmacological profile, “[aspirin] could be a means to improving the burden of disease [ie, GI cancers],” they added.