Corrie Marijnen started her training as radiation-oncologist in 1994 in the Academic Hospital Leiden. During her residency, she started with her PhD, which she achieved with honors in 2002 . After working for 4 years in the Netherlands Cancer Institute, she became chair of the department of Radiotherapy at Leiden University Medical Center. During that time, she was closely involved in the HollandPTC, the joined protonfacility of the LUMC, ErasmusMC and TU Delft. In 2019 she moved back to the Netherlands Cancer Institute, where she is currently working as chair of the department of Radiation Oncology. She is professor in Radiotherapy, with a focus on clinical research, at the Leiden University Medical Center. In the past 15 years, Corrie Marijnen concentrated her research on the treatment of rectal cancer, with special attention on toxicity and quality of life. She has been actively involved in many clinical rectal trials, such as the TME, STARTREC, HERBERT and RAPIDO trial. Based on this experience, she contributed to clinical and delineation guidelines, nationally and internationally. MR-guided radiotherapy, reducing overtreatment, total neoadjuvant treatment, organ preservation and shared decision making are topics that play an important role in her current research lines.