Regular aspirin use has been associated with a reduction in the development of a number of different malignancies including lung cancer. The mechanism of aspirin's cancer prevention is not known. This study will evaluate whether once daily aspirin use can reduce the production of a protein named prostaglandin E2 (PGE-2), which is known to promote cancer. Specifically, this study will evaluate if aspirin can inhibit the production of PGE-2 by blocking an enzyme named cycloxygenase-2 (COX-2). To accomplish these goals, participants will take either aspirin 325 mg daily, celecoxib 200 mg twice daily, or the combination of both during various days of this 16-day study. Urine be collected to evaluate for PGE-2 production at 4 timepoints in this 16-day study.

Inclusion Criteria:

• Male gender
• Age ≥35
• Current smoker of at least 10 cigarettes per day with history of ≥10 pack-years (py)
• Former smoker, quit no more than 15 years ago with a history of at least 25 py
• Ability to comply with the design of the study
• Capacity to freeze urine sample at participant's residence if this participant desires to store the urine specimens in this manner
• Baseline urine PGE-M > 13 ng/mg creatinine
• Serum thromboxane > 150 μg/L

Exclusion Criteria:

• History of aspirin use 1-14 days prior to screening
• NSAID (ibuprofen, naprosyn, meloxicam, etc) use 1-7 days prior to screening
• Inhaled glucocorticoid use 1-7 days prior to screening
• Systemic glucocorticoid use 1-14 days prior to screening
• History of peptic ulcer disease
• Current or recent clinically significant bleeding
• Allergy, intolerance or contraindication to aspirin or NSAID use
• Thrombocytopenia (platelet count < 100,000) in 30 days prior to screening visit
• Severe hepatic insufficiency
• GFR < 30 mL/min/1.73 m2 in 30 days prior to screening visit
• History of aspirin or celecoxib allergy
• Elevated INR (>1.5) in 30 days prior to screening visit
• Current diagnosis of malignancy or history of non-skin malignancy in last 5 years
• Current use of systemic anticoagulants (e.g., warfarin (Coumadin), enoxaparin (Lovenox), Fondaparinux (Arixtra), dabigatran (Pradaxa))
• Diagnosis of COPD
• Intake of > 250 mg of fish oil supplementation daily