Background The cost of new cancer technologies has been the subject of intense debate in recent years. There have been significant advances in therapeutic techniques for breast cancer over the past 20 years. This has been accompanied by the concentration of services in designated cancer centres. The aim of this study was to examine the changing cost of breast cancer management over an 18-year period and identify factors underlying this.Methods We use breast cancer services data from Galway University Hospital in 1995-1996, 2005-2006 and 2011-2012 to examine the changing pattern of care costs and survival.Results The number of patients treated for breast cancer rose from 200 in 1995-1996, to 411 in 2005-2006 and 563 in 2011-2012. Two-year survival rose in line with national figures from 84 to 89.78 and 92.07%, in the three-time periods respectively. Adjusting for inflation, the average cost per patient rose from (sic)14,710 (95% C. I., (sic)13,398 to (sic)16,022) in 1995-1996 to (sic)30,405 (95% C. I., (sic)38,620 to (sic)32,189) in 2005-2006, before falling to (sic)14,458 (C. I., (sic)13,343 to (sic)15,572) in 2011-2012. We found significant changes in the pattern of costs, with some rising in relative and absolute terms while others fell as new therapies became available and/or moved off patent.Conclusion Within an evolving context where services are centralised, new therapies emerge and subsequently come off patent, our understanding of the value of cancer therapies continues to evolve. This has important implications for the evaluation of new therapies and broader policy initiatives in this area.