Dr. Siu is a senior medical oncologist at Princess Margaret Cancer Centre since 1998, and has been a Professor of Medicine at the University of Toronto since 2009. She is the Director of the Phase I Program and Co-Director of the Bras and Family Drug Development Program at Princess Margaret Cancer Centre, and holds the BMO Chair in Precision Genomics (2016-2026). She is also the Clinical Lead for the Tumor Immunotherapy Program at Princess Margaret Cancer Centre. Dr. Siu served on the Board of Directors for the American Society of Clinical Oncology (ASCO) for a four-year term (2012-2016); she served on the American Association for Cancer Research (AACR) Board of Directors for a three-year term (2017-2020).

Dr. Siu’s major research focus is in the area of new anticancer drug development, particularly with respect to phase I trials and head and neck malignancies. She is the co-Contact PI of a phase I UM1 grant sponsored by the United States National Cancer Institute.

Internationally, Dr. Siu was the recipient of the US NCI Michaele C. Christian Award in Oncology Drug Development in 2010. She was awarded the TAT 2020 Honorary Award for contributions in the development of anticancer drugs. In 2023, Dr. Siu was recognized for her educational efforts by the ASCO International Women Who Conquer Cancer Mentorship Award.

Dr. Siu has published over 400 peer-reviewed manuscripts, and she is currently the co-Editor-in-Chief for AACR’s newest journal Cancer Research Communications, and is on the editorial board for Cell and Cancer Cell.