Marniza Saad is a Clinical Oncologist at the Universiti Malaya Medical Centre (UMMC) and an Associate Professor at the Faculty of Medicine, Universiti Malaya. She is currently serving her second tenure as Head of the Department of Clinical Oncology, a leadership role she previously held from 2013 to 2015. During her first tenure, she spearheaded the establishment of advanced radiotherapy services at UMMC, including Intensity Modulated Radiotherapy (IMRT) and Stereotactic Radiosurgery/Radiotherapy (SRS/SRT). She pioneered the development of the multidisciplinary team (MDT) culture at UMMC. Together with the urology team, she established the first Genitourinary (GU) MDT at UMMC in 2010, transforming it into a core learning environment for trainees.

After obtaining her medical degree from the University of Wales, UK, in 1997, she was awarded the Fellowship of the Royal College of Radiologists (FRCR) in Clinical Oncology in 2006 following her training at the Velindre Cancer Centre in Cardiff. Since her return to Malaysia, she has been a central figure in national medical education for clinical oncology. She served as the lead for the Clinical Oncology National Postgraduate Medical Curriculum from 2015 to 2021. This has now become the reference curriculum in the country. Her deep expertise in curriculum development was recognized globally when she was invited by the International Atomic Energy Agency (IAEA) in 2023 to serve as an advisor for developing a radiation oncology curriculum for low- and middle-income countries.

Her standing as a key opinion leader in GU oncology at national and the Asia-Pacific region is reflected in her appointments to national and international scientific committees. She has served on the scientific committee for ESMO Asia including as co-chair for its GU track. She has also been appointed to the scientific committee for the inaugural ESMO GU Cancers Asia Congress in 2027. Her leadership is evident in her work co-authoring crucial regional guidelines, including the APAC Advanced Prostate Cancer Consensus Conference (APCCC) and the Pan-Asian adapted E(PAGA) ESMO guidelines. As an active researcher, she is the national principal investigator for numerous landmark clinical trials, publishing transformative findings in top-tier journals such as the Annals of Oncology and the Journal of Clinical Oncology.

She is also deeply committed to shaping national health policy and professional standards. She has served on the executive committee of the Malaysian Oncological Society (MOS) and was appointed as a council member of the College of Oncologists Academy of Medicine Malaysia in 2025. Her service extends to the broader hospital community through her leadership in patient welfare, with roles on the Board of Trustees for the University Malaya Urological Cancer Trust Fund (UCTF) and continued advisory role for the Prostate Cancer Society Malaysia (PCSM).