PURPOSE: To investigate whether patients requiring radiation treatment are prepared to travel to alternative more distant centers in response to hospital choice policies, and the factors that influence this mobility. METHODS AND MATERIALS: We present the results of a national cohort study using administrative hospital data for all 44,363 men who were diagnosed with prostate cancer and underwent radical radiation therapy in the English National Health Service between 2010 and 2014. Using geographic information systems, we investigated the extent to which men choose to travel beyond ("bypass") their nearest radiation therapy center, and we used conditional logistic regression to estimate the effect of hospital and patient characteristics on this mobility. RESULTS: In all, 20.7% of men (n=9161) bypassed their nearest radiation therapy center. Travel time had a very strong impact on where patients moved to for their treatment, but its effect was smaller for men who were younger, more affluent, and from rural areas (P for interaction always <.001). Men were prepared to travel further to hospitals that offered hypofractionated prostate radiation therapy as their standard schedule (odds ratio 3.19, P<.001), to large-scale radiation therapy units (odds ratio 1.56, P<.001), and to hospitals that were early adopters of intensity modulated radiation therapy (odds ratio 1.37, P<.001). CONCLUSIONS: Men with prostate cancer are prepared to bypass their nearest radiation therapy centers. They are more likely to travel to larger established centers and those that offer innovative technology and more convenient radiation therapy schedules. Indicators that accurately reflect the quality of radiation therapy delivered are needed to guide patients' choices for radiation therapy treatment. In their absence, patient mobility may negatively affect the efficiency and capacity of a regional or national radiation therapy service and offer perverse incentives for technology adoption.