Early identification of patients in need of radiotherapy treatment intensification would allow tailored radiotherapy dose. We hypothesize that patients with poor vascularity or hypoxia will correlate with these patients, and T1 changes from oxygen-enhanced MRI could provide indications of tumour perfusion. We acquired T1-maps before and after 8-10 fractions of radiotherapy and examined whether the oxygen-enhanced MRI response relates to clinical outcome. There was a significant increase in tumour T1 across patients following chemoradiotherapy (p<0.001). Before chemoradiotherapy, OE-MRI showed no significant changes in tumour T1, however after receiving chemoradiotherapy, OE-MRI showed a significant decrease in tumour T1 (p<0.001).