Objective: In Finland, the overall costs of breast cancer management have increased, primarily during the last years by the launch of expensive pharmaceutical therapies (trastuzumab in 2000). Economical reasons may therefore play a part in the prescribing of new drugs. We analyzed with comprehensive time series of all expenditures the effectiveness of pharmaceutical developments and other interventions from 1987 to 2005. Methods: : Finnish registry based data from 1987 to 2005 was combined to evaluate all costs related to the care of breast cancer. These included comprehensive health care costs, sick-leave compensations, disability pensions, and loss of productivity; all converted to 2004 euros. Several scenarios were thereafter constructed to identify the important changes in care processes and cost drivers during this period. Results: During the observation period, the number of patients with breast cancer (5-year survival prevalence) increased by 100% up to 17,000 patients and the overall expenditure of care more than doubled from €70 to €160 million. The health care costs increased by 150% and the cumulative costs per patient increased from €4500 to €5500. The cost of medications has escalated with an overall increase of 660%, mostly during 2000's. However, during this period, the effectiveness of the treatment has increased as breast cancer related deaths, in-hospital days and loss of productivity due to premature deaths have decreased significantly. Altogether, our scenarios showed that new medications have had a beneficial financial impact of 16-35 million € for the society during the study period. Conclusion: Comprehensive assessment of large patient cohorts and long term economical outcomes is a useful method for evaluation of outcomes in chronic diseases. Identification of different cost drivers is needed as the cost of new interventions is increasing and their benefits should ideally be assessed in relation to their broader societal influence.