In breast oncology, the increasing number of oral and intravenous drug therapies pose great challenges for patient management. Numerous studies demonstrate that well-informed patients develop higher confidence in their treatment and a greater sense of disease control, resulting in increased adherence and persistence as well as potentially better outcome. The electronic Patient Reported Outcome (ePRO) tool CANKADO is designed to help oncologists to fill the gap between good, personalized care and a time and resource-saving treatment for cancer patients. CANKADO helps patients and their physicians regarding therapy management by a standardized documentation procedure and, if needed, direct feedback to patients by the integrated Pro-React system. GeRA includes patients undergoing systemic therapy for breast cancer with access to CANKADO. The trial is based on questionnaires that are answered by patients via the CANKADO Patient App. Primary objective is to gain knowledge on the health economic impact of CANKADO resource utilization in breast cancer care including the evaluation of physicians' time and patient experience.

Inclusion Criteria:

• Men and women with breast cancer
• Ongoing medical drug treatment
• 18 years or older
• CANKADO account

Exclusion Criteria:

• Lack of consent to study participation or lack of patient's ability to stuconsent

Patients under medical treatment for breast cancer with access to CANKADO will be included in the analysis. This study will take place in at least 10 German centers with CANKADO access / participation representatively distributed in Germany.