Findings demonstrated that chronic obstructive pulmonary disease (COPD) patients had a lower risk of lung carcinoma and lung carcinoma–related mortality in relation to low-dose aspirin use. While aspirin was not linked with an elevated risk of upper gastrointestinal bleeding, the risk of hemoptysis was increased.

• COPD is a prevalent risk factor of lung cancer, and aspirin is a medication with potential anticancer effects but its impact on lung cancer remains controversial.

• Among patients with COPD, defined as aspirin nonusers (35,049) and aspirin users (7,679 patients), lung carcinoma risk was assessed by using a territory-wide database.

• Employing a mathematical model, the 2 cohorts were balanced by their comorbidities, drug uses, demographic variables, and proxy variables for their socioeconomic status.

• A 25% lower risk of lung carcinoma was observed in relation to aspirin use, implying that within this cohort, every 125 patients treated for 5 years is linked with one fewer case of lung carcinoma.

• Aspirin use was found to be linked with an elevated risk of coughing up blood, although the overall risk of gastrointestinal bleeding was not elevated.