Progression to Metastatic Breast Cancer According to Stage and Biomarker Status at Diagnosis in Denmark: A Register-Based Cohort Study

Speaker(s)

Liseth Hansen J1, Johnsen M2, Fischer F3, Kopp T2, Ström O3
1Quantify Research, Oslo, Norway, 2Quantify Research, Copenhagen, Denmark, 3Quantify Research, Stockholm, Sweden

OBJECTIVES: In the Nordics, new treatments have emerged, offering targeted therapies tailored to the specific pathophysiology of breast cancer (BC). These therapies are more effective with fewer side effects than conventional chemotherapy. It's crucial to monitor treatment trends, effectiveness, patient selection, and safety closely. The current study aims to study usability and coverage of administrative register-based data with focus on biomarkers and metastatic progression in BC patients in Denmark.

METHODS: BC patients were identified in national administrative registers in Denmark from January 1, 2011 to December 31, 2018 and followed until progression to stage IV, death or end of follow-up, i.e., December 31, 2021. Patients were categorized according to stage and biomarker status (hormone receptor (HR) and HER2). Descriptive statistics and 3-year cumulative incidence of progression to stage IV treating death as a competing event were carried out stratified by stage and biomarker status.

RESULTS: In total, 29,271 patients with stage I-III BC were identified, of which 15,852 (54%) had stage I, 11,069 (38%) had stage II and 2,350 (8%) had stage III at time of diagnosis. 28,675 (98%) had complete records of HR and HER2 status at time of diagnosis. The mean time to metastatic progression were 3.9 years (stage I), 3.7 years (stage II) and 3.5 years (stage III). The 3-year cumulative incidence of metastatic progression was highest among patients with “triple negative” BC (i.e., ER-/HER2-) regardless of diagnostic stage: 0.04 (95% confidence interval (CI), 0.03-0.05) for stage I, 0.09 (95% confidence interval (CI), 0.07-0.10) for stage II, and 0.22 (95% confidence interval (CI), 0.17-0.27) for stage III.

CONCLUSIONS: The Danish administrative registers are of high quality and with high completeness. Results from this study demonstrate the widespread potential for utilizing these registers within real-world evidence of targeted treatments in patients with BC.

Code

EPH146

Topic

Epidemiology & Public Health

Topic Subcategory

Public Health

Disease

Oncology