Purpose: To our knowledge it is unknown whether stereotactic body radiation therapy of prostate cancer is a substitute for other radiation treatments or surgery, or for expanding the pool of patients who undergo treatment instead of active surveillance.
Materials and methods: Using SEER (Surveillance, Epidemiology, and End Results)-Medicare we identified men diagnosed with prostate cancer between 2007 and 2011. We developed physician-hospital networks by identifying the treating physician of each patient based on the primary treatment received and subsequently assigning each physician to a hospital. We examined the relative distribution of prostate cancer treatments stratified by whether stereotactic body radiation therapy was performed in a network by fitting logistic regression models with robust SEs to account for patient clustering in networks.
Results: We identified 344 physician-hospital networks, including 30 (8.7%) and 314 (91.3%) in which stereotactic body radiation therapy was and was not performed, respectively. Networks in which that therapy was and was not done did not differ with time in the performance of robotic and radical prostatectomy, and active surveillance (all p >0.05). The relationship with intensity modulated radiation therapy did not show any consistent temporal pattern. In networks in which it was performed less intensity modulated radiation therapy was initially done but there were similar rates in later years. Brachytherapy trends differed among networks in which stereotactic body radiation therapy was vs was not performed with a lower brachytherapy rate in networks in which stereotactic body radiation therapy was done (p=0.03).
Conclusions: Surgery and active surveillance rates did not differ in networks in which stereotactic body radiation therapy was vs was not performed but when that therapy was done there was a lower brachytherapy rate. Stereotactic body radiation therapy may represent more of an alternative to brachytherapy than to active surveillance.
Keywords: SEER Program; brachytherapy; prostatic neoplasms; radiotherapy; watchful waiting.