Background of the PROSPeCT study

Colorectal cancer is one of the commonest causes of cancer death worldwide. In the UK there are approximately 42,000 new cases annually. Up to 50% of patients still die from their disease ultimately. Surgery remains the mainstay of curative treatment, and refinement in surgical technique, e.g. total mesorectal excision for rectal cancer, has improved local recurrence rate. However, distant relapse rates have remained relatively stable despite ‘potentially curative’ surgery, with up to 50% developing metastases by 5 years. Ultimate patient outcome is very poor once metastases are present with 5-yr survival as low as 3%.

A better understanding of the biology of colorectal cancer has resulted in a shift in therapeutic focus. Firstly, the introduction of targeted therapies, e.g., cetuximab, targeted at epidermal growth factor receptor (EGFR) and more recently, immunotherapies. Secondly, a shift in delivery of chemotherapy from the post-operative (adjuvant) to pre-operative (neoadjuvant) setting. These advances have the potential to enhance patient survival, but have highlighted a need for better identification of high-risk patients when initial staging is performed, especially a subgroup of Stage II/Dukes’B patients who would not usually be offered chemotherapy as standard care.

The PROSPeCT study aims to improve the prediction of recurrent disease in patients with colorectal cancer by developing a prognostic model based on disease-free survival, via evaluation of conventional predictive clinicopathological variables and novel imaging variables resulting from Perfusion CT.