Aspirin Use Negatively Associated With CRC Incidence

Aspirin use was found to have an association with a decreased risk of overall, proximal, and rectal cancer, according to a study published in the Journal of Korean Medical Science.¹ This includes in patients with hypertension (HTN) and diabetes mellitus (DM).

The incidence of colorectal cancer (CRC) has been increasing significantly around the world and occurring in younger populations.² Preventive strategies are crucial to reducing the risk of CRC, including addressing metabolic diseases. Aspirin can be used to prevent CRC due to its anti-inflammatory and anti-tumor effects but the association between CRC and aspirin has been varied and inconclusive. This study aimed to assess the association between aspirin use and the risk of CRC in patients with HTN and DM.

Patients with newly diagnosed CRC were included from the Center for Colorectal Cancer of the National Cancer Center (NCC) in Korea. Data between August 2010 and September 2020 were included. Controls were also from the NCC and were patients that had undergone a health screening in the center. Patients who did not complete a lifestyle questionnaire were excluded from the study. Patients were also excluded if they did not have information on blood pressure, fasting glucose level, a history of HTN and DM, aspirin use and duration, and anatomical site of CRC. Patients were matched in a 1:2 ratio of cases to controls based on age and sex.

Age, socioeconomic status, body mass index (BMI), and family history of CRC were among the data collected for the study. Patients who had a history of HTN, a systolic blood pressure above 130 mmHg, or diastolic blood pressure above 80 mmHg were considered to have HTN. Patients were categorized into 4 categories: neither HTN or DM, only HTN, only DM, and both HTN and DM. Aspirin use was self-reported and included the duration of time that it was used: no use, less than 5 years, and 5 years or more.

There were 1331 cases and 2771 controls that were included in this study. The cases included 415 of the proximal colon, 448 of the distal colon, and 468 rectal cancer. The mean (SD) age of the participants with cancer was 58.3 (10.3) years. and the mean age of the controls was 57.6 (9.4) years. Lower education and income levels were found in patients with CRC.

A total of 1191 participants had neither HTN nor DM whereas 2044 had HTN only, 203 had DM only, and 664 had both HTN and DM. Overall and site-specific CRC was associated with having HTN and/or DM after adjustment. Overall CRC had an adjusted OR of 1.41 (95% CI, 1.15-1.73) in patients with HTN only. Patients with DM only had an adjusted OR of 6.92 (95% CI, 4.67-10.26), and patients who had both HTN and DM had an adjusted OR of 8.43 (95% CI, 6.37-11.16).

Distal colon cancer had an increased risk of occurring in patients with HTN (OR, 1.96; 95% CI, 1.43-2.68) and patients with DM had a positive association with proximal colon cancer (OR, 7.27; 95% CI, 4.25-12.45), distal colon cancer (OR, 7.75; 95% CI, 4.46-13.49), and rectal cancer (OR, 7.03; 95% CI, 4.24-11.68).

Overall CRC was negatively associated with the use of aspirin with an adjusted OR of 0.31 (95% CI, 0.13-0.45). This association remained the same when looking at the anatomical sites for CRC, including the proximal colon (OR, 0.24; 95% CI, 0.13-0.45), the distal colon (OR, 0.36, 95% CI, 0.21-0.62), and the rectum (OR, 0.33; 95% CI, 0.17-0.61). These associations also were maintained despite the duration of the use of aspirin and whether the patient had either HTN or DM.

There were some limitations to this study. Recall bias and selection bias are possible due to the case-control study design. Measurement bias and inaccuracies could be possible due to the self-reported nature of the aspirin use measurements. Fasting glucose levels and self-reported DM were the only measurements of DM used, and could have underestimated the prevalence of DM. This study only focused on suggesting an association between aspirin duration and risk of CRC, as there was an absence of information about the dosage of aspirin intake and cancer stage.

The researchers concluded that aspirin had a negative association with the risk of CRC, with aspirin use leading to a decreased risk of overall, proximal, and rectal cancers in patients with HTN and DM. Preventing CRC with the use of aspirin is therefore a suitable strategy in patients that are at high risk of developing the cancer.

References

1. An S, Gunathilake M, Lee J, et al. Relationship between aspirin use and site-specific colorectal cancer risk among individuals with metabolic comorbidity. J Korean Med Sci. 2024;39(26):e199. doi:10.3346/jkms.2024.39.e199
2. Colorectal cancer facts & figures 2023-2025. American Cancer Society. 2023. Accessed July 9, 2024. https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/colorectal-cancer-facts-and-figures/colorectal-cancer-facts-and-figures-2023.pdf