Personalised Disease Monitoring in Metastatic Breast Cancer

Prior treatment

• Known CNS metastases, carcinomatous meningitis or leptomeningeal disease unless treated with radiotherapy and symptomatically stable at least 2 weeks after discontinuation of steroids. For such patients, ongoing monitoring of CNS disease is required as standard of care. No screening is needed for asymptomatic patients.
• Concurrent disease(s) or familial, sociological or geographical condition that would, in the investigator's opinion, preclude compliance with study procedures.

Other illness

• Any serious medical disorder that would compromise the patient's safety.
• Dementia altered mental status, or any psychiatric condition that would prevent the understanding or rendering of Informed Consent.

• Confirmed metastatic breast cancer (stage 4) or locally advanced disease not amendable to curative resection. Patients who have locoregional disease only an in whom a response to therapy would lead to potentially curative resection are not eligible.
• ER+/HER2- breast cancer (assessed locally). NOTE: If immunohistochemical analysis is not available from metastatic tissue, the ER and HER2 status from the primary tumour should be used.
• For patients who have had a prior non-breast malignancy within the last 5 years (excluding in situ carcinoma of the cervix and basal cell carcinoma of the skin) biopsy of a metastatic site is required to confirm the diagnosis of metastatic ER+/HER2- breast cancer.
• Eligible for 1st line endocrine treatment with AI + CDK4/6-inhibitor according to local guidelines.
  • NOTE: ≥ 12 month since termination of adjuvant AI if used NOTE: Patients may have received one prior line of chemotherapy for metastatic breast cancer but should have disease progression at study entry.
• Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-2 (Oken 1982).
• Life expectancy \>3 months.
• Age ≥ 18 years
• Metastatic disease must be radiologically assessable, by means of at least one of the following techniques: computerised tomography (CT) and/or magnetic resonance imaging (MRI), i.e. lesions can be measurable or non-measurable according to RECIST 1.1, but must be clearly evaluable according to the radiologist and/or treating physician. Patients with bone predominant disease who lack evaluable disease on CT according to RECIST 1.1.
  • must have serial MRI including the representative area in addition to CT TAP. NOTE: Previously irradiated lesions are deemed measurable only if progression is documented at the site after completion of radiation.
  • \- Willing and able to provide informed consent to undergo all trial procedures.