Background: Breast cancer mortality rates vary substantially across multiple patient and tumour factors. Large-scale data can show the effects of these factors. Long term follow-up is needed because breast cancer deaths continue to occur more than 20 years after the original cancer diagnosis. Sources of data held by Public Health England on patients with cancer have increased in recent years and now have the potential to be the best source of population-based information on outcomes worldwide.

Materials: Large-scale population data were collated on all women registered with early invasive breast cancer in England during 1993-2016. Data were available on: year of diagnosis, age at diagnosis, mode of presentation (screen-detected or not), tumour size, number of involved lymph nodes, grade, oestrogen receptor status, tumour laterality, deprivation, geographical region and date and cause of death up to 31st December 2017. These data were reviewed and improved. Population-based estimates of the absolute 5, 10, 15 and 20-year risks of breast cancer mortality were derived for women in different prognostic groups.

Results/conclusions: Over 500,000 women were diagnosed with early invasive breast cancer during 1993-2016, and around 70,000 of them subsequently died from breast cancer. More than 20 years’ follow-up was available for around 30,000 women, and more than 15 years for around 100,000 women. Breast cancer mortality varied substantially according to patient factors such as age at presentation and calendar year of diagnosis and tumour factors such as screening status, size, node positivity and oestrogen receptor status. Breast cancer mortality rates from these large-scale population-based data may be used to estimate mortality for patients diagnosed with breast cancer today. They are relevant to decisions concerning which treatments and follow-up strategies to use.