Background
Metastatic breast cancer (MBC) represents the most advanced stage of breast malignancy, where cancer cells have spread beyond the breast and regional lymph nodes to distant organs. Despite advances in systemic therapies including hormonal therapy, chemotherapy, and targeted agents, MBC remains largely incurable, with a 5-year survival rate of approximately 30%. Treatment decisions in this setting are critically important, as ineffective therapy not only fails to control disease but also exposes patients to unnecessary toxicity and diminishes quality of life.
The current standard approach to monitoring treatment response relies primarily on computed tomography (CT) imaging performed after 8-12 weeks of therapy. However, this delayed assessment window may postpone recognition of treatment failure, prolonging exposure to ineffective agents. Furthermore, CT primarily evaluates anatomical changes, which may lag behind actual tumor metabolic activity. This limitation has spurred interest in functional imaging modalities that can detect early biological changes in response to therapy.
