Inclusion Criteria:

- Women with metastatic breast cancer

- ECOG performance status 0-2

- Age over18 years

- Signed informed concent

- Predicted life expectancy over 2 months

- Planned for first line systemic treatment for metastatic disease (chemotherapy,
antibody treatment or endocrine treatment)

- Standard imaging evaluation within 4 weeks of inclusion

- Planned for standard imaging within 16 weeks after start of therapy

Exclusion Criteria:

- Prior medical therapy for metastatic disease (prior adjuvant chemotherapy,
radiotherapy or endocrine therapy is permitted)

- Inability to understand information about the study

- Other malignant disease with the exception of curatively treated basal cell or
squamous cell cancer of the skin and cancer in situ of the cervix