Abstract Introduction: The announcement of the diagnosis of metastatic breast cancer is a key step in enabling the patient to fully understand her disease and the various treatment options, and thus to be more involved in her management and follow-up. However, according to the « Croyances et réalités 2 » survey conducted in 2021 among 269 French patients with metastatic breast cancer, 38% of them felt that they "did not fully understand" the information given by their doctor during the announcement consultation. Objective: The objective of this work is to model an optimal pathway for the announcement of metastatic breast cancer based on precise guidelines and good coordination between the different actors, in order to ensure that all patients have the necessary information and support. Method: A scientific committee composed of 4 French oncologists from 4 different centers initiated a collaborative process to propose, after discussions, precise guidelines for the announcement of metastatic breast cancer. Results: A set of 13 concrete guidelines were suggested by the expert group (Table 1). The central aspect is to build a specialized and flexible support, adapted to the needs of the patient, without ever hiding the truth about her disease. The announcement process must be adapted to the patient's history (recurrent or immediately metastatic), but also to the organization and resources available in the health care institution. The experts recommend a model of announcement process in two stages, separated by a few days. First, the oncologist announces what the entry into metastatic disease represents, followed by a repeat of the announcement by a nurse trained in the specificities of metastatic breast cancer, in order to have the patient reformulate her understanding of the disease and treatment. In a second phase, a new consultation allows to present the next therapeutic steps and ensure a coordinated intervention of the different health care professionals involved: doctors, nurses, pharmacists and supportive care specialists as needed. The offer of supportive care should be flexible and it is recommended that questionnaires should be made available to the patient to help identify her precise needs. The experts recommend that this second consultation be conducted jointly by an oncologist and a nurse. Subsequently, the town physician and pharmacist must be contacted to ensure the relay in the accompaniment of the patients in partnership with the cancer care center, and thus to ensure a good sharing of information on the patient's follow-up. To help the establishment of this dynamic announcement model, the experts gave advice on implementation: training the professionals involved in the process through theoretical training and role-playing, increasing the amount of time spent on the announcement consultation, and setting up a library of online or physical information materials to share with the patient. Finally, it is recommended that the financing of this process be prepared at the institutional level before its effective implementation in order to ensure its sustainability. Conclusion: Organizing a consultation for the announcement of metastatic breast cancer is essential to optimize the experience of the announcement and support. It must be a structured, funded and coordinated process between different health professionals specially trained for this approach. Table 1: Summary of guidelines for a metastatic breast cancer notification pathway. Citation Format: Florence Dalenc, Séverine Guiu, Marie-Ange Mouret-Reynier, Nathalie Quenel-Tueux. Women with Metastatic Disease: Modeling a Clear and Well-Defined Announcement Pathway [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-11-03.