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Updated: May 16, 2026
Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
Published on: February 21, 2014
Validation of a proxy for estrogen receptor status in breast cancer patients using dispensing data
Preeyaporn Srasuebkul1, Timothy A Dobbins,
1Prince of Wales Clinical School and Lowy Cancer Research Centre, Faculty of Medicine, University of New South Wales; Pharmacoepidemiology and Pharmaceutical Policy Research Group, Faculty of Pharmacy, University of Sydney.
Aim:
To assess the performance of a proxy for estrogen receptor (ER) status in breast cancer patients using dispensing data.
Methods:
We derived our proxy using 167 patients. ER+ patients had evidence of at least one dispensing record for hormone therapy during the lookback period, irrespective of diagnosis date and ER- had no dispensing records for hormone therapy during the period. We validated the proxy against our gold standard, ER status from pathology reports or medical records. We assessed the proxy's performance using three lookback periods: 4.5 years, 2 years, 1 year.
Results:
More than half of our cohort (62%) were >50 years, 54% had stage III/IV breast cancer at recruitment, (46%) were diagnosed with breast cancer in 2009 and 23% were diagnosed before 2006. Sensitivity and specificity were high for the 4.5 year lookback period (93%, 95% CI: 86-96%; and 95%: 83-99%), respectively) and remained high for the 2-year lookback period (91%: 84-95%; and 95%: 83-99%). Sensitivity decreased (83%: 75.2-89%) but specificity remained high (95%: 83-99%) using the 1-year lookback period and the period is long enough to allow sufficient time for hormone therapy to be dispensed.
Conclusion:
Our proxy accurately infers ER status in studies of breast cancer treatment based on secondary health data. The proxy is most robust with a minimum lookback period of 2 years.
