Incidence and survival of primary metastatic breast cancer in Denmark; implication of breast cancer screening, classification, and staging practice

Authors

  • Tobias Berg Danish Breast Cancer Group, Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark
  • Maj-Britt Jensen Danish Breast Cancer Group, Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark
  • Maria Rossing Center for Genomic Medicine, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
  • Christian T. Axelsen Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
  • Iben Kümler Department of Oncology, Copenhagen University Hospital, Herlev Hospital, Herlev, Denmark
  • Lise Søndergaard Department of Oncology, Zealand University Hospital, Næstved Sygehus, Denmark
  • Marianne Vogsen Department of Oncology, Odense University Hospital, Odense, Denmark; Department of Clinical Research, University of Southern Denmark, Odense, Denmark
  • Ann S. Knoop anish Breast Cancer Group, Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark
  • Bent Ejlertsen anish Breast Cancer Group, Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark

DOI:

https://doi.org/10.2340/1651-226X.2023.37270

Keywords:

Breast cancer, metastatic, survival, epidemiology

Abstract

Background: Primary metastatic breast cancer (pMBC) accounts for 5–10% of annual breast cancers with a median survival of 3–4 years, varying among subtypes. In Denmark, the incidence of breast cancer increased until 2010, followed by a stabilisation. Several factors influencing pMBC incidence and survival, including screening prevalence, staging methods, and classification standards, remain pivotal but inadequately documented.

Material and method: This retrospective observational study involving pMBC patients diagnosed between 2000 and 2020 encompassed all Danish oncology departments. Data from the Danish Breast Cancer Group database and the National Patient Register included diagnosis specifics, demographics, treatment, and follow-up.

Results: Between 2000 and 2020, 3,272 patients were diagnosed with pMBC, a rise from 355 patients in 2000–2004 to 1,323 patients in 2015–2020. The increase was particularly observed in patients aged 70 years or older. Changes in tumour subtypes were observed, notably with a rise in human epidermal growth factor receptor 2 (HER2)-positive cases but a steady distribution of estrogen receptor (ER) status. Diagnostic practices changed over the two decades, with 6% evaluated with PET/CT (positron emission tomography–computed tomography) or CT (computed tomography) with a bone evaluation in 2000–2004 and 65% in 2015–2020. Overall survival (OS) improved from 23 months in 2000–2004 to 33 months in 2015–2020. In patients with ER-positive and HER2-positive disease, the multivariable model showed improved survival by year of diagnosis, and further, patients with ER-negative/HER2-negative disease fared worse the first 2 years after diagnosis.

Interpretation: Our study delineates changes in the treatment and survival of pMBC over two decades. Stage migration, screening introduction, and changes in registration practice, however, prevent a valid assessment of a possible causal relationship.

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Published

2024-05-06

How to Cite

Berg, T., Jensen, M.-B., Rossing, M., Axelsen, C. T., Kümler, I., Søndergaard, L., … Ejlertsen, B. (2024). Incidence and survival of primary metastatic breast cancer in Denmark; implication of breast cancer screening, classification, and staging practice . Acta Oncologica, 63(1), 277–287. https://doi.org/10.2340/1651-226X.2023.37270