In an era where quality of life and symptom management are increasingly recognized as critical to effective cancer treatment, PRO offers an invaluable lens through which patients can communicate the real-world impact of therapies. This comprehensive whitepaper by Ergomed CRO dives deep into the development and application of PRO tools, illustrating how they provide insights into patients' day-to-day experiences, treatment tolerability, and long-term well-being. With the inclusion of PRO data, sponsors and healthcare providers can make more informed decisions, improving not only clinical trial outcomes but also helping to refine therapeutic strategies that better meet patients’ needs.