Advanced radiotherapy techniques in prostate cancer

Abstract

Prostate cancer (PC) is the most common tumor in males. Treatment options for localized prostate cancer include radical prostatectomy and radiation therapy (RT), which is delivered either as external beam radiation therapy (EBRT) or brachytherapy (BRT). According to "European Association of Urology" guidelines, although radical prostatectomy is the gold standard treatment option in localized PC, definitive RT could be an alternative treatment option in medically inoperable patients or who refused surgery. Treatment of PC has been evolving since the last decades with the innovation in technology. More precise radiotherapy (RT) techniques provides sharper isodoses while sparing organs at risk (OAR). It is also important that setup margins could be reduced with image guidance. Hence, precisely defining targets and considering organ movement are gaining much more importance. As a consequence of sharper isodoses and image guidance, dose escalation comes into question. It is well known that there is a positive correlation between RT dose and biochemical progression-free survival (BPFS) but not overall survival (OS) rates, with dose escalated conventionally fractionated up to 76-80 Gy in 2 Gy fractions, which is a biologically equivalent dose (BED1.5) of 180-200 Gy, assuming an α/β of 1.5. A recent meta-analysis clearly demonstrated an increased disease control with a BED1.5 to 200 Gy, with no additional clinical benefit with doses above 200 Gy. In order to deliver higher doses to the prostate without increasing surrounding organs at risk, it is essential to delineate target volumes properly, deliver RT with high-technology devices, immobilize patient, and track prostate during RT. The aim of this chapter is to review recent advances in prostate RT.