Age is the major risk factor for breast cancer in women, with 50% of cases being diagnosed in those over 65 years of age. Epidemiological evidence suggests that cyclooxygenase (COX)-2 inhibitors can reduce the incidence of breast cancer by 20% and these agents are more likely to be prescribed for older women to ameliorate the symptoms of osteoarthritis (OA). In women over 65 years of age who develop breast cancer, the majority of their tumors are estrogen-receptor (ER) positive, and it is this subtype whose growth is inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs). Careful use of these agents could provide a strategy for both relief of symptoms of OA and also breast cancer prevention. Instead of the customary approach of a prospective randomized trial, proof of the hypothesis could be obtained from an adequately powered cohort study, based on the NHS breast screening programme.