Is robotic arm stereotactic body radiation therapy 'virtual high-dose rate brachytherapy' effective for prostate cancer? An analysis of comparative effectiveness using published data

High-dose rate brachytherapy (HDR-BT) monotherapy and robotic arm (i.e., CyberKnife) stereotactic body radiation therapy (SBRT) are emerging technologies that have become popular treatment options for prostate cancer. Proponents of both HDR-BT monotherapy and robotic arm SBRT claim that these modalities are as efficacious as intensity-modulated radiation therapy in treating prostate cancer. Moreover, proponents of robotic arm SBRT believe it is more effective than HDR-BT monotherapy because SBRT is non-invasive, touting it as 'virtual HDR-BT.' We perform a comparative effective analysis of the two technologies. The tumor control rates and toxicities of HDR-BT monotherapy and robotic arm SBRT are promising. However, at present, it would be inappropriate to state that HDR-BT monotherapy and robotic arm SBRT are as efficacious or effective as other treatment modalities for prostate cancer, which have stronger foundations of evidence. Studies reporting on these technologies have relatively short follow-up time, few patients and are largely retrospective.