Improving the Treatment for Women With Early Stage Cancer of the Uterus

Inclusion Criteria: 1. Females with a BMI \> 30 kg/m2 wishing to retain fertility or females who are at high risk of surgical complications due to co-morbidities or obesity 2. Over 18 years of age at time of randomisation 3. Histologically confirmed complex endometrial hyperplasia with atypia or grade 1 endometrioid endometrial adenocarcinoma on a curette or endometrial biopsy 4. CT or MRI scan of pelvis, abdomen and chest (or chest X-Ray) suggesting the absence of extrauterine disease 5. Myometrial invasion on MRI of not more than 50%, for women with histologically confirmed Endometrial Cancer only (for women who are unable to fit into an MRI machine inclusion into trial is at investigators discretion) 6. No lymph vascular invasion on curetting or pipelle, if able to be assessed on sample 7. Serum CA125 ≤ 30 U/mL 8. No hypersensitivity or contraindications for Mirena 9. Ability to comply with endometrial biopsies at specified intervals 10. Negative serum or urine pregnancy test in pre-menopausal women and women \< 2 years after the onset of menopause 11. Creatinine \< 150µmol/L (1.7 mg/dL) to be randomised into Mirena + Metformin arm (can still be eligible to be randomised to Mirena only or Mirena + Weight Loss, see section 5.4 Other Eligibility Criteria Considerations) Exclusion Criteria: 1. ECOG performance status \> 3 2. Grade 1 endometrioid adenocarcinoma of the endometrium with myometrial invasion deeper than 50% on MRI or any patients with grade 2 or grade 3 endometrioid adenocarcinoma 3. Histological (cell) type other than endometrioid adenocarcinoma (sarcomas or high risk endometrial e.g. papillary serous, clear cell) 4. Pregnant or planning to become pregnant during trial period 5. Has had prior treatment or undergoing current treatment for EAC or EHA 6. Patients with a history of pelvic or abdominal radiotherapy 7. Unwilling to have additional endometrial biopsies or curettes and unable to attend three monthly clinical assessments 8. Unable to provide informed consent 9. Unable or unwilling to complete questionnaires 10. Evidence of extrauterine spread on medical imaging 11. Congenital or acquired uterine anomaly which distorts the uterine cavity 12. Acute pelvic inflammatory disease 13. Conditions associated with increased susceptibility to infections with microorganisms (e.g., AIDS, leukaemia, IV drug abuse) according to the patients Medical History 14. Genital actinomycosis 15. Current other cancer, except low grade malignancies that do not require any systemic treatment or treatment to the pelvis 16. Breastfeeding mothers 17. Mirena inserted greater than 12 weeks before randomisation/enrolment 18. Previous use of Mirena within the last 5 years from randomisation/enrolment 19. Contraindications to both Metformin and weight loss