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Title: Perfusion imaging and tissue biomarkers for colorectal cancer
Author: Hill, Esme
ISNI:       0000 0004 6061 934X
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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Background: Systemic chemotherapy and radiotherapy play an important role in the treatment of colorectal cancer. Tumour perfusion and oxygenation is known to influence radiosensitivity and chemosensitivity. In this thesis, I propose that the evaluation of changes in tumour perfusion using perfusion CT (pCT) and dynamic contrast-enhanced (Dce) MRI can guide the rational sequencing of drugs and radiation. Methods: Dce-MRI and pCT scans were incorporated into a clinical trial of hypofractionated pelvic radiotherapy and nelfinavir in 10 patients with rectal cancer. Toxicity and tissue biomarkers (tumour cell density, microvessel density, CAIX, HIF1-alpha, phospho-Akt and phospho-PRAS40) were evaluated. pCT liver scans were incorporated into an imaging study in patients with colorectal liver metastases randomised to receive either oxaliplatin/ 5FU chemotherapy or oxaliplatin/ 5FU chemotherapy plus selective internal radiotherapy. Results: After 7 days of nelfinavir concurrent with hypo-fractionated pelvic radiotherapy, there was a mean 42% increase in median Ktrans (P=0.03, paired t test) on Dce-MRI and a median 30% increase in mean blood flow on pCT (P=0.028, Wilcoxon Rank Sum), although no statistically significant changes in perfusion parameters were demonstrated after 7 days of nelfinavir prior to radiotherapy. The feasibility of evaluating tumour cell density in rectal biopsies before and after radiotherapy and a radiosensitising drug as an early endpoint of response was demonstrated. In patients with colorectal liver metastases who received oxaliplatin and modified de Gramont chemotherapy alone, after 4 cycles of chemotherapy, a 28% decrease in the mean hepatic arterial fraction was observed (P=0.018, paired t test). Between pCT scans 2 days before SIRT and 39-47 days following SIRT and continued 2-weekly chemotherapy, there was a mean 62% (P=0.009) reduction in Blood Flow and 61% (P=0.006) reduction in Blood Volume (paired t test). Conclusions This research does not support the hypothesis that nelfinavir before radiotherapy improves blood flow to human rectal cancer. Increases in rectal tumour perfusion during radiotherapy and concurrent nelfinavir are likely to be primarily explained by the acute biological effects of radiation. Four or more cycles of oxaliplatin and modified de Gramont chemotherapy may result in changes in tumour perfusion of colorectal liver metastases which would be detrimental to subsequent radiotherapy. Selective internal radiotherapy resulted in substantial reductions in tumour perfusion 39-47 days after the treatment. Perfusion imaging can be used to detect changes in tumour perfusion in response to radiotherapy and systemic therapy which have implications for the sequencing of therapies.
Supervisor: Sharma, Ricky ; Partridge, Mike Sponsor: CRUK-ESPRC Oxford Cancer Imaging Centre
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Selective Internal Radiotherapy (SIRT) ; Nelfinavir ; Colorectal cancer ; Biomarkers ; Perfusion Imaging ; Tumour Cell Density ; Radiosensitisation ; Selective Internal Radiotherapy ; Dynamic contrast-enhanced MRI ; Chemotherapy ; Perfusion CT ; Radiotherapy