Concern regarding the economic aspect of cancer care has been increasing in the face of mounting healthcare expenditure in Japan. The need, not only for effective, but also for efficient treatment options in breast cancer care have been recognized in a broader context. In clinical practice, treatment options in first-line therapy for advanced breast cancer have become similar to those in Western countries in the past 5 to 10 years in the context of so-called 'evidence-based medicine' employing clinical evidence; whereas evidence of cost-effectiveness has been less acknowledged. Limited economic evidence suggests that current Japanese practice in first-line hormonal therapy is cost-effective. However, the efficiency of other options, such as chemotherapy, remains unknown. The expanding use of an expensive molecular-targeting agent, trastuzumab, has great implications for a treatment algorithm for breast cancer as well as for cost-effectiveness of care. Trastuzumab, of which use in first-line therapy was not found to be cost-effective in Western countries, is expected to be used for a number of HER2-overexpressing primary breast cancers in Japan. The extension of indication of this single agent would increase national healthcare expenditure by 0.1%. The authors believe explicit discussion on value for money of new expensive drugs would be unavoidable, not only among health policy makers, but also leading breast cancer specialists in Japan in the near future.