Parameters affecting tumour control and toxicity in oesophageal cancer: a multi-dimensional outcome analysis
Carrington, Dewi Rhys
The work contained within this thesis explores the relationship between clinical and technological parameters of radiotherapy treatment planning and patient outcome in patients who were treated for cancer of the oesophagus as part of the SCOPE 1 clinical trial. However the methods and concepts of the work could also have applications at other tumour sites.\ud By developing ideas from previous studies, a novel method of applying a conformity index found a significant relationship between the quality of a radiotherapy plan and patient outcome in terms of overall survival. Furthermore it was found that the plan quality could be improved by utilising a relatively new method of dose delivery. This dose delivery method also allowed the improving of tumour control via dose escalation to be explored via radiobiological modelling. The results of this work showed that although the probability of controlling the tumour is increased, there is also a significantly higher risk of increased gastric toxicity for patients with lower oesophageal tumours. Interfraction gastric movement was also investigated with the end result being a recommendation for stomach movement and toxicity to be minimised by using a pre-treatment protocol. This is being taken forward in a nationwide multicentre clinical trial. Finally a texture analysis software package was used to investigate whether there was relationship between the image heterogeneity parameters of computed tomography images and patient outcome. This work could potentially aid the decision making process of radiotherapy treatment, allowing a more informed judgement to be made on the most beneficial treatment for the patient.