This is Episode 24: Nasopharynx IV Response Assessment and Salvage. Building upon the previous two episodes, we have established that nasopharyngeal carcinoma is a radiation-driven disease. We have reviewed the anatomy, EBV biology, staging, and evidence supporting concurrent chemoradiation, with or without induction. Now, we address the critical question patients will invariably pose: "Did it work?" More importantly, we will explore the appropriate course of action when the answer is negative. This episode delves into high-stakes scenarios. Recurrent NPC following definitive chemoradiation presents one of the most complex decision points in head and neck oncology. The available options include surgery, re-irradiation, or systemic therapy; however, an incorrect decision can have catastrophic consequences. Treatment-related mortality in the re-irradiation setting can exceed 10%. Risks such as carotid blowout syndrome, temporal lobe necrosis, and nasopharyngeal hemorrhage are not merely theoretical concerns but represent the daily realities of managing recurrent disease. By the conclusion of this episode, you will be equipped to assess response, determine appropriate intervention strategies, and counsel patients through what may be the most critical treatment decision of their lives.