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Abstract
Background
Breast cancer is the commonest cancer in the UK, with around 55,000 women diagnosed annually. Information is routinely available on breast cancer mortality but not on recurrence.
Methods
We used a database compiled by the West Midlands Cancer Intelligence Unit during 1997–2011 to develop and train a deterministic algorithm to identify recurrences in routinely collected data (RCD) available within NHS England. We trained the algorithm further using 150 women with stage II-III breast cancer who were recruited into the AZURE trial during 2003–2006 and invited to approximately 24 clinic follow-up visits over ten years. We then evaluated its performance using data for the remaining 1930 women in England in the AZURE trial.
Results
The sensitivity of the RCD to detect distant recurrences recorded in the AZURE trial during the ten years following randomisation was 95.6% and its sensitivity to detect any recurrence was 96.6%. The corresponding specificities were 91.9% for distant recurrence and 77.7% for any recurrence.
Conclusions
These findings demonstrate the potential of routinely collected data to identify breast cancer recurrences in England. The algorithm may have a role in several settings and make long-term follow-up in randomised trials of breast cancer treatments more cost-effective.
Details

1 University of Oxford, Nuffield Department of Population Health, Oxford, UK (GRID:grid.4991.5) (ISNI:0000 0004 1936 8948)
2 National Disease Registration Service, National Cancer Registration and Analysis Service, Birmingham, UK (GRID:grid.4991.5)
3 University of Sheffield, Department of Oncology and Metabolism, Sheffield, UK (GRID:grid.11835.3e) (ISNI:0000 0004 1936 9262)
4 University of Leeds, Leeds Cancer Research Clinical Trial Unit, Leeds, UK (GRID:grid.9909.9) (ISNI:0000 0004 1936 8403)
5 University of Oxford, Nuffield Department of Population Health, Oxford, UK (GRID:grid.4991.5) (ISNI:0000 0004 1936 8948); University of Oxford, Nuffield Department of Surgical Sciences, Oxford, UK (GRID:grid.4991.5) (ISNI:0000 0004 1936 8948)