Comparison of external beam radiotherapy versus permanent seed brachytherapy as monotherapy for intermediate-risk prostate cancer - a single center Canadian experience
Delouya, G.; Lambert, C.; Bahary, J.-P.; Beauchemin, M.-C.; Barkati, M.; Ménard, C.; Taussky, D.
Canadian Journal of Urology 24(3): 8822-8826
2017
ISSN/ISBN: 1195-9479 PMID: 28646937 Document Number: 693250
We tested different classification systems in order to separate intermediate-risk prostate cancers into prognostic groups. We then examined which groups were most suited for either prostate seed brachytherapy (PB) or external beam radiotherapy (EBRT). We selected patients with D'Amico intermediate-risk prostate cancer who were treated exclusively with either PB or EBRT. Patients were excluded if they had received androgen deprivation therapy in combination with EBRT or a follow up of < 30 months without recurrence. The Kaplan-Meier method was used to compare groups. Our sample consisted of 475 patients treated from July 2002-September 2013. Median follow up for patients without biochemical failure (BF) was 56 months (interquartile range 44-78); 222 patients (47%) were treated with PB exclusively (D90 interquartile range 145-176 Gy) and 253 (53%) with EBRT exclusively (dose interquartile range 76-80 Gy). The rate of BF was significantly lower in patients treated with PB (5.4%) than in patients treated with EBRT (14.2%) (p = 0.036, log-rank test). Upon univariate analysis, significant predictors of BF included the number of unfavorable intermediate-risk factors (0, 1, 2, 3) (p = 0.024) as well as the Cancer of the Prostate Risk Assessment (CAPRA) score (p = 0.002). After adjusting for the type of treatment, only the CAPRA score remained predictive (p = 0.025). For patients with a CAPRA score of 0-2, those with PB fared better than those treated with EBRT (p = 0.042). This difference disappeared in patients with a CAPRA score of 3-5 (p = 0.5). Using our current selection criteria for monotherapy, we found that PB or EBRT as monotherapy are equally effective treatment options for intermediate-risk prostate cancer.