The impact of image guided external beam radiotherapy on outcome in treating intermediate risk cancer prostate

Background: Intermediate-risk prostate cancer is a highly heterogeneous 
disease. Treatment options include various radiotherapy techniques with a short 
course of androgen deprivation therapy (ADT), or combination external beam 
radiotherapy (EBRT) with a brachytherapy (BT) boost with or without ADT.
The benefits of image guided radiotherapy (IGRT) have been shown in 
retrospective series and it has become the standard of care for delivery of 
external beam radiation treatment for prostate cancer.
Purpose of the study: To compare the biochemical and clinical tumor control 
in patients treated by means of high dose IGRT versus high dose non image 
guided (non IG EBRT) as well as the toxicity profile in both techniques.
Patients and Methods: This is a retrospective study that enrolled patients with 
localized cancer prostate of intermediate risk treated with EBRT either with or 
without image guidance between 1995 and 2012.
Results: A cohort of 388 consecutive patients was enrolled. IGRT achieved 
significantly longer biochemical failure free survival (p = 0.016) only patients 
with favorable criteria have gained this advantage (p=0.055). T1C, total Gleason 
score 6, percent of positive biopsy cores ≤ 50% gained significantly longer 
bFFS compared with other subgroups. Concerning distant failure, IGRT, percent 
of positive biopsy cores ≤ 50%, favorable criteria and T1C were significantly 
associated with longer DFFS. ADT with radiotherapy showed significantly 
lower DFFS rates. Only total Gleason score that significantly has affected the 
local failure free survival (LFFS).
Conclusions: Prostate cancer with unfavorable intermediate risk should ideally 
be treated with dose escalated IGRT with more longer treatment of ADT.