Prostate-specific antigen kinetics following external-beam radiotherapy and temporary (Ir-192) or permanent (I-125) brachytherapy for prostate cancer
Received 19 August 2009; received in revised form 21 December 2009; accepted 14 February 2010. published online 15 March 2010.
Abstract
Background and purpose
The aim of the study was the evaluation of PSA kinetics after different radiotherapy methods.
Materials and methods
Two-hundred and ninety five patients received external-beam radiotherapy (EBRT; 70.2Gy; n=135), Ir-192 brachytherapy as a boost to EBRT (HDR-BT; 18Gy+50.4Gy; n=66) or I-125 brachytherapy (LDR-BT; 145Gy; n=94) as monotherapy. “PSA bounce” was defined as a PSA rise of ⩾0.2ng/ml followed by spontaneous return to prebounce level or lower, biochemical failure as “nadir+2ng/ml”.
Results
Patients without biochemical failure reached a lower nadir after brachytherapy (median ⩽0.05ng/ml after LDR- and HDR-BT without NHT) in comparison to EBRT (0.55ng/ml without NHT; p<0.01). Not a single patient without NHT and a nadir <0.1ng/ml failed biochemically (0% vs. 45% with a nadir ⩾0.1ng/ml; p<0.01). PSA bounces were found predominantly in the LDR-BT group (42% vs. 23%/20% after HDR-BT/EBRT; p<0.01). In a multivariate Cox regression analysis, LDR-BT and HDR-BT were associated with a significantly lower biochemical failure rate in comparison to EBRT.
Conclusions
PSA kinetics differ significantly following different radiotherapy methods. A lower nadir and a higher biochemical control rate suggest a higher radiobiological efficiency of brachytherapy in comparison to EBRT (with a dose of 70.2Gy).
ABSTRACT