ABSTR AC T IntroductionThe care of patients with breast cancer is extremely complex and requires interdisciplinary care in certified facilities. These specialized facilities provide numerous services without being correspondingly remunerated. The question whether breast cancer surgery should be performed in an outpatient setting to reduce costs is increasingly being debated. This study compares inpatient surgical treatment with a model of the same surgery performed on an outpatient basis to examine the potential financial impact.Material and Methods A theoretical model was developed and the DRG fees for surgical interventions to treat primary breast cancer were calculated. A theoretical 1-day DRG was then calculated to permit comparisons with outpatient procedures. The costs of outpatient surgery were calculated based on the remuneration rates of the AOP (Outpatient Surgery) Contract and the EBM (Uniform Assessment Scale) and compared to the costs of the 1-day DRG.Results The DRG fee for both breast-conserving surgery and mastectomy is higher than the fee paid in the context of the EBM system, although the same procedures were carried out in both systems. If a hospital were to carry out breast-conserving surgery as an outpatient procedure, the fee would be € 1313.81; depending on the type of surgery, the hospital would therefore only receive between 39.20 % and 52.82 % of the DRG fee. This was the case even for a 1-day treatment. Compared to the real DRG fees the difference would be even more striking.Conclusion Carrying out breast cancer surgery as an outpatient procedure would result in a significant shortfall of revenues. Additional services from certified centers, such as the interdisciplinary planning of treatment, psycho-oncological and social-medical care with the involvement of relatives, detailed documentation, etc., which are currently provided without surcharge or adequate remuneration, could no longer be maintained. The quality of processes and excellent results which have been achieved and ultimately the care given by certified facilities would be significantly at risk. Since the introduction of the diagnosis-related fee-per-case system (G-DRG, German Diagnosis-Related Groups) in Germany, in addition to medical aspects more and more emphasis is placed on economic considerations. Reducing costs while maintaining or even improving the quality of care is the most urgent objective. Surgical care has been the topic of much heated debate. The Medical Services of the Health Insurance Companies (MDK) are increasingly reviewing cases with the aim of reducing costs. The consequences are a reduction in the length of inpatient stays and deductions to fees when patients are in hospital for less than the minimum stipulated length of stay. In addition, the question whether surgery for breast cancer could be done in an outpatient setting is being increasingly debated. Interventions such as lumpectomy and sentinel lymph node biopsy are already partly listed in the catalog of outpatient surgeries. This in turn places...