Endometrial cancer is the most common gynaecological cancer in New Zealand, and incidence rates are rising, particularly in younger women. Research is needed to meet ongoing disparities in health outcomes and to timely address the changing population affected by this disease. A higher number of women with endometrial cancer, or pre-lesions, are being treated with the Mirena intra uterine device when unable to have surgery or want fertility-sparing options. Around 40% of tumours will not respond to this type of treatment, and there is a significant gap in the literature around why this is, and if we can predict the type of response. Our project will be the first to investigate whether packaged information in the form of RNA can be measured in blood, in the attempt to provide a predictive and non-invasive test.