About the PhD thesis

Current treatment of patients with rectal cancer is highly effective with respect to local tumor control, but also carries the risk of substantial late morbidity burden. This PhD thesis investigated high-dose radiotherapy (as a boost to primary tumor and suspected malignant lymph nodes), with a focus on understanding day-to-day positional variations of the tumor and lymph nodes to optimize radiotherapy treatment plans as part of a non-operative alternative.

The thesis includes three studies based on data from two prospective clinical studies.

Study I evaluated positional variations of the primary tumor using two different methods, uncovering substantial local surface displacements, and introducing a method to quantify these relative to the tumor’s location in the rectum.

Study II examined positional variation of suspected malignant lymph nodes, identifying dependencies on their pelvic location and the impact of factors such as bladder filling.

Study III analyzed high-dose treatment plans from three Danish radiotherapy centers, revealing inter-center differences yet confirming the feasibility of proposed treatment planning goals for future prospective evaluations aimed at organ preservation.

This research advances our understanding and develops robust methods for evaluating and treating boost target volumes, providing valuable insights into high-dose boost radiotherapy for rectal cancer patients, crucial for improving radiotherapy treatment for these patients.