Oral Maintenance Therapy in Early Breast Cancer—How Many Patients Are Potential Candidates?

Background/Objectives: This single-center analysis evaluated the number of potential candidates for endocrine-based oral maintenance therapy in a real-world setting, focusing on three therapeutic agents, namely, olaparib, abemaciclib, and ribociclib, for patients with hormone receptor-positive HER2-negative early breast cancer. Methods: All breast cancer cases from the past 10 years (n = 3230) that underwent treatment at the certified Breast Cancer Center of the Department of Gynecology and Obstetrics, University Hospital Schleswig-Holstein, Lübeck Campus, were analyzed. Results: Of a total of 2038 patients with HR+ HER2− eBC, 685 patients (33.6%) qualified for one or more of the three agents—olaparib, abemaciclib, and ribociclib. Of these 685 patients, 523 patients (76.4%) had node-positive and 162 (23.6%) node-negative disease. Moreover, 368 patients (18.1% of a total of 2038 patients with HR+ HER2− eBC) were eligible exclusively for ribociclib, including all node-negative patients. A total of 141 patients (6.9%) met the criteria for all three agents. In contrast, 1353 patients (66.4%) had no indication for combined endocrine therapy. Conclusions: To our knowledge, this is the largest analysis addressing all three therapeutic strategies for combined endocrine therapy. The broad indication criteria of the NATALEE study may increase clinic workloads due to more frequent physician/patient interactions. It also remains unclear how therapy recommendations will influence actual treatment, as increased visits and potential side effects could affect patient compliance and adherence.