Lillian L. Siu is a senior medical oncologist and internationally recognized leader in early-phase cancer drug development. She is Director of the Phase I Clinical Trials Program at the Princess Margaret Cancer Centre, where she also co-directs the Robert and Maggie Bras and Family Drug Development Program, serves as Clinical Lead for the Tumor Immunotherapy Program, and holds the BMO Chair in Precision Cancer Genomics. She is a Professor of Medicine at the University of Toronto.
Throughout her career, Dr. Siu has made major contributions to translational and clinical research, with a particular focus on improving the design and execution of clinical trials. Her work has accelerated the development of novel immunotherapies and targeted treatments for patients with head and neck and gastrointestinal cancers. She is the 2025–2026 President-Elect of the American Association for Cancer Research (AACR) and a Fellow of the AACR Academy. Her leadership and impact have been recognized with the 2024 ASCO David A. Karnofsky Memorial Award and the 2024 CAHON Lifetime Achievement Award.
The 100 Most Influential People in Oncology in 2025 recognizes the changemakers in cancer care who have helped shape current practice in oncology and continue to drive innovation and research towards better outcomes, advocacy, philanthropy, leadership and education. For the many deserving individuals not mentioned in this list, we will continue to acknowledge, honor and elevate your voices in our daily publications from across the world.
See the full list of The 100 Influential People in Oncology in 2025 and stay tuned for the results of special category nominations to be announced.
