The National Cancer Institute estimates more than 600,000 Americans will die of cancer in 2020. A number of meta-analyses have demonstrated the ability of prolonged daily aspirin use to reduce the risk of multiple types of cancers (including gastrointestinal cancers, adenocarcinomas, and other solid tumors. A recent study reports aspirin may have adverse effects on the progression of cancer in older adults.
Many healthcare professionals prescribe aspirin to their older patients to reduce their risk of heart attack and stroke. Aspirin inhibits the enzyme cyclooxygenase (COX)-1 and downstream production of thromboxanes, a group of lipids that causes blood vessel constriction and increases adhesion between platelets and circulating cancer cells. By inhibiting thromboxane production, aspirin decreases inflammation, hypertension, and cancer metastasis.
This randomized controlled trial included more than 19,000 healthy Australian and US participants over the age of 65 years. The investigators randomly assigned participants to take 100 milligrams of enteric coated aspirin daily or a placebo for an average of nearly five years. They obtained cancer incidence and death rates via clinical records.
While the rate of new cancer onsetof onset of new cancers was similar between the aspirin and placebo groups, cancer patients in the aspirin group were more likely to be diagnosed with advanced-stage and metastatic cancers. Death rates from solid tumor cancers, but not blood or lymphatic, were higher in the aspirin group.
Interestingly, the authors suggested this increase in cancer severity and death may be due to aspirin’s anti-inflammatory effects. Inflammation is critical in the body’s fight against cancer, but this defense weakens with age, and aspirin use may further weaken this response.
The authors note that while their study design was strong, further research is needed to confirm their findings. Several randomized controlled trials further investigating this topic are underway.
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