Univariate Cox Proportional Hazard analysis of clinical, biopsy and imaging variables for the prediction of treatment failure in 262 patients with 35 treatment failures. HR = Hazards ratio. REF indicates the reference category to which the other categories are compared. For the continuous variables, the Hazards ratio indicates the percentage increase in the chance of a treatment failure event for a unit increase in the variable. For example, a 1.07 HR for age at diagnosis indicates that the chance of treatment failure increases by 7% for every year of increase in age. For the categorized variables, the HR indicates the percentage increase in the chance of TF compared to the reference category. All variables were significant (p < 0.05-p < 0.0001).