Incidence of colorectal cancer in new users and non-users of low-dose aspirin without existing cardiovascular disease: A cohort study using The Health Improvement Network

Safety and effectiveness of low-dose aspirin for the prevention of gastrointestinal cancer in adults without atherosclerotic cardiovascular disease: a population-based cohort study

OBJECTIVE

To assess the association between low-dose aspirin and the incidence of colorectal cancer (CRC), gastric cancer (GC), oesophageal cancer (EC) and gastrointestinal bleeding (GIB) in adults without established atherosclerotic cardiovascular disease.

DESIGN

Cohort study with propensity score matching of new-users of aspirin to non-users.

SETTING

Clinical Data Analysis and Reporting System database, Hong Kong.

PARTICIPANTS

Adults ≥40 years with a prescription start date of either low-dose aspirin (75-300 mg/daily) or paracetamol (non-aspirin users) between 1 January 2004 to 31 December 2008 without a history of atherosclerotic cardiovascular disease.

MAIN OUTCOME MEASURES

The primary outcome was the first diagnosis of gastrointestinal cancer (either CRC, GC or EC) and the secondary outcome was GIB. Individuals were followed from index date of prescription until the earliest occurrence of an outcome of interest, an incident diagnosis of any type of cancer besides the outcome, death or until 31 December 2017. A competing risk survival analysis was used to estimate HRs and 95% CIs with death as the competing risk.

RESULTS

After matching, 49 679 aspirin and non-aspirin users were included. The median (IQR) follow-up was 10.0 (6.4) years. HRs for low-dose aspirin compared with non-aspirin users were 0.83 for CRC (95% CI, 0.76 to 0.91), 0.77 for GC (95% CI, 0.65 to 0.92) and 0.88 for EC (95% CI, 0.67 to 1.16). Patients prescribed low-dose aspirin had an increased risk of GIB (HR 1.15, 95% CI, 1.11 to 1.20), except for patients prescribed proton pump inhibitors or histamine H2-receptor antagonists (HR 1.03, 95% CI, 0.96 to 1.10).

CONCLUSION

In this cohort study of Chinese adults, patients prescribed low-dose aspirin had reduced risks of CRC and GC and an increased risk of GIB. Among the subgroup of patients prescribed gastroprotective agents at baseline, however, the association with GIB was attenuated.

Aspirin for prevention of colorectal cancer in the elderly: friend or foe?

Cancer is the leading cause of death among men and women aged 60-79 years. Colorectal cancer is the third most common cancer in males and the second most common in females, with about 0.8 million deaths worldwide per year. Individuals older than 50 years account for 20-50% of colonic adenomas. Several measures have been proposed to decrease colorectal cancer risks, such as an increase in dietary fiber, use of aspirin, and physical activity. Nonsteroidal anti-inflammatory drugs have been proposed as protective agents against the development of colorectal cancer and colorectal adenomas. Aspirin was the first pharmacological agent endorsed by the United States Preventive Services Task Force screening for colorectal cancer chemoprevention. Although studies have shown up to 40% colorectal cancer risk reduction in individuals at average risk, data regarding this benefit are inconsistent. Several recent studies show that prophylactic use of aspirin in elderly subjects may not be beneficial in preventing the occurrence of colorectal cancers. Given the risks associated with aspirin, such as non-fatal and fatal bleeding events, aspirin's role should be redefined, especially in individuals at risk of bleeding. This review provides a discussion of the recent studies on the role of aspirin use in elderly individuals at risk of colorectal cancer.

Effects of aspirin on the gastrointestinal tract: Pros vs. cons

Acetylsalicylic acid, also known as aspirin, is often used in clinical antipyretic, analgesic and antiplatelet therapy. Aspirin can cause numerous side effects in the gastrointestinal (GI) tract, ranging from unpleasant GI symptoms without gastric mucosal lesions to ulcer bleeding and even death. However, recent studies have found that aspirin can significantly prevent GI tumors. Despite impressive advances in cancer research, screening and treatment options, GI tumors remain a leading cause of death worldwide. Prevention is a far better option than treatment for tumors. Therefore, the present review assesses the pros and cons of aspirin on the GI tract and, on this the basis, the appropriate dose of aspirin to protect it.

Low-dose aspirin and risk of gastric and oesophageal cancer: A population-based study in the United Kingdom using The Health Improvement Network

There is increasing interest regarding potential protective effects of low‐dose aspirin against various gastrointestinal cancers. We aimed to quantify the association between use of low‐dose aspirin and risk of gastric/oesophageal cancer using a population‐based primary care database in the UK. Between January 2005 and December 2015, we identified a cohort of 223 640 new users of low‐dose aspirin (75‐300 mg/day) and a matched cohort of nonusers at the start of follow‐up from The Health Improvement Network. Cohorts were followed to identify incident cases of gastric/oesophageal cancer. Nested case‐control analyses were conducted and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for current vs nonuse of low‐dose aspirin using logistic regression. Current use was defined as when low‐dose aspirin lasted 0 to 90 days before the index date (event date for cases, random date for controls) and previous duration was ≥1 year. We identified 727 incident cases of gastric cancer and 1394 incident cases of oesophageal cancer. ORs (95% CIs) were 0.46 (0.38‐0.57) for gastric cancer and 0.59 (0.51‐0.69) for oesophageal cancer. The effect remained consistent with no clear change seen between previous duration of low‐dose aspirin use of 1‐3, 3‐5 or >5 years. The reduced risks was seen with 75 mg/day, and effects were consistent in lag‐time analyses. In conclusion, our results indicate that use of low‐dose aspirin is associated with a 54% reduced risk of gastric cancer and a 41% reduced risk of oesophageal cancer as supported by mechanistic data.

What's new?

Low‐dose aspirin may help protect against the development of gastric and oesophageal cancers. This population‐based study using data from primary care electronic health records in the United Kingdom lends further support to that idea. Compared with no use of low‐dose aspirin, daily use of low‐dose aspirin (75–300 mg) for at least one year was associated with a 54 percent reduction in gastric cancer risk and a 41 percent reduction in oesophageal cancer risk. No clear difference in effect was observed between low‐dose aspirin use for one to three years versus more than three years.