OBJECTIVES: This study aimed to use patient-level data to provide up-to-date estimates of early invasive breast cancer care costs by stage in England and to explore to what extent these costs varied based on patients' ages and geographic regions. METHODS: This study identified women aged 50 years and older who had been diagnosed with early invasive breast cancer between January 1, 2014, and December 31, 2015, using linked cancer registrations and routine hospital data sets generated from the usual care for all National Health Service trusts in England. Cost estimates were derived from hospital records in Hospital Episodes Statistics with additional chemotherapy and radiotherapy information from the national data sets. We fitted general linear regression models to analyze the cost data. The model that best fit the data was selected using the model selection criteria of Akaike information criterion. RESULTS: 55 662 women with early invasive breast cancer in England were included. The generalized linear model with log-gamma distribution fit the data best. The costs of breast cancer care for 1 year after diagnosis were strongly dependent on stage at diagnosis, controlling for other covariates. The estimated average per-patient hospital-related costs were £5167 at stage I, £7613 at stage II, and £13 330 at stage IIIA. Costs decreased with increasing age (P < .001) and varied across region (P < .001), deprivation level (P < .001), referral source (P < .01), presence of comorbidities (P< .001), and tumor receptor (ER/PR/HER2) status (P < .001). CONCLUSIONS: In England, the costs of breast cancer care increased with advancing stage of the disease at diagnosis. Breast cancer costs varied by age and geographic region.