Clinical Research Directory

Inclusion Criteria: * Patient with first presentation of MBC, regardless of ER and HER2 status of the primary tumor, who is eligible for first-line systemic therapy. * Patient with non-rapidly progressive MBC, not requiring urgent initiation of chemotherapy, based on clinician's evaluation which may include: * no recent (\< 2 weeks prior to screening visit) significant worsening of MBC related signs and symptoms according to patient history. * in case of liver metastases: no significant increase in liver function tests alanine aminotransferase aspartate transaminase (ASAT) and alanine transaminase (ALAT) in 2 weeks prior to screening visit. (Significant increase of liver function test is defined as 50% increase of absolute amount of ASAT/ALAT.) * Patients in whom standard imaging work-up of MBC was recently (≤ 28 days) performed. Standard imaging must include: CT chest/abdomen, 18F-FDG-PET and bone scintigraphy. * Patient with measurable or clinically evaluable (bone only) disease on recent standard work up of MBC are eligible. * Metastatic lesion(s) of which a histological biopsy can safely be obtained according to standard clinical care procedures. * Primary tumor blocks available for confirmatory central laboratory ER/HER2 testing in the UMCG. If available a snap frozen sample of the primary tumor will also be centralized in the University Medical Center Groningen (UMCG). * WHO performance status 0-2. * Patient is able to undergo PET imaging procedures. * Age \>18 years of age, willing and able to comply with the protocol as judged by the investigator. * Signed written informed consent. Exclusion Criteria: * Contraindications for systemic treatment (as will be assigned based on biopsy and experimental scan results), either chemotherapy, hormonal therapy or anti-HER2 therapy, based on clinical judgment of treating medical oncologist and patient history. * Pregnant or lactating women. * Prior allergic reaction to immunoglobulins or immunoglobulin allergy. * Inability to comply with study procedures. * Rapidly progressive (visceral) disease requiring rapid initiation of chemotherapy.