Pre-surgical aromatase inhibitor combined with non-steroidal anti inflammatory drug treatment in breast cancer

INTERVENTION: in window of time between diagnosis and surgery, post‐menopausal women with ER positive breast cancer will be treated with an aromatase inhibitor alone, letrozole 2.5mg daily oral tablet, or with aspirin 200mg twice daily, oral tablet, in an anti inflammatory dose. Adherence will be monitored by twice weekly nurse review, and blood estradiol levels. CONDITION: post menopausal breast cancer PRIMARY OUTCOME: change in biological markers, including inflammation and proliferation, over 14 days of treatment. Pre‐ and post treatment tumour samples will be compared, and studied by immunohistochemistry for immune cell subsets, inflammatory cells, and tumour cell Ki67. Gene expression profiling using the same tumour samples will also be studied at a later stage. SECONDARY OUTCOME: safety of aspirin over 14 days, including peri‐operatively, by twice weekly nurse assessment before and after surgery, using standard toxicity grading, recorded on CRF for specific side effects of interest. INCLUSION CRITERIA: ER positive, stage 1‐2 breast cancer, post‐menopausal, no prior therapy