Combining Interventions of Fertility Preservation to Mitigate Fertility Loss After Breast Cancer

Inclusion Criteria: * Age ≥ 18 and ≤ 35 years * BMI ≥ 18 and ≤ 35 kg/m² * Diagnosis of breast cancer * Presence of 2 ovaries * Signed informed consent form * Medically fit for general anesthesia (ASA score 1-3) * Permission of oncology team (with agreement to postpone chemo/radiotherapy for at least 2 weeks) * Random start controlled ovarian stimulation * AFC minimum (ie antral follicles measuring between 2-9 mm): 8 antral follicles Exclusion Criteria: * Age \<18 or \>35 years * BMI \<18 or \>35 kg/m² * Difference in AFC between the ovaries of more than 7 antral follicles * Diagnosis of PCOS * Previous radiotherapy and/or chemotherapy (neo-adjuvant chemotherapy included) * Endometriose rAFS 3-4 * Allergy or reaction to the use of Elonva®, Puregon®, Orgalutran®, Pregnyl® Gonapeptyl®, Decapeptyl® or letrozole in the past