Published online Aug 24, 2019. doi: 10.5306/wjco.v10.i8.283
Peer-review started: February 27, 2019
First decision: April 11, 2019
Revised: May 5, 2019
Accepted: July 30, 2019
Article in press: July 30, 2019
Published online: August 24, 2019
Historically, testosterone level of < 50 ng/dL has been used to define castrate level after surgery or after androgen deprivation treatment in metastatic prostate cancer (PC). However, recent studies show better outcomes when threshold was below 20 ng/dL. In this study we evaluate the effect of two different castrate testosterone levels on biochemical relapse free survival in patients with non-metastatic intermediate and high risk PC receiving definitive modern radiotherapy and androgen deprivation treatment.
Current literature seeking for the answer of the castrate testosterone level question for non-metastatic disease is small and heterogeneous.
The aim of the study was to evaluate the effect of two different castrate testosterone levels, < 50 and < 20 ng/dL, on treatment outcomes in patients with non-metastatic intermediate and high risk prostate cancers receiving definitive RT and ADT. This is the first study to evaluate the castrate levels on biochemical relapse free survival for non-metastatic prostate cancer patients.
Between April 1998 and February 2011; 173 patients with intermediate and high risk disease were treated. Radiotherapy was delivered by either three-dimensional-conformal technique to a total dose of 73.4 Gy at the ICRU reference point or intensity modulated radiotherapy technique to a total dose of 76 Gy. All the patients received 3 mo of neoadjuvant ADT followed by RT and additional 6 mo of ADT. ASTRO Phoenix definition was used to define biochemical relapse.
Median follow up duration was 125 months. Ninety-six patients (56%) had castrate testosterone level < 20 ng/dL and 139 patients (80%) had castrate testosterone level < 50 ng/dL. Both values are valid at predicting BRFS. However, patients with testosterone < 20 ng/dL have significantly better BRFS compared to other groups (P = 0.003). When we compare two values, it was found that using 20 ng/dL is better than 50 ng/dL in predicting the BRFS (AUC = 0.63 vs 0.58, respectively).
In current study serum testosterone was measured using modern immunoassay method. With a median follow up time of 125 mo, our treatment outcomes are in consistent with the literature supporting the use of lower castrate testosterone level. It seems that lowering testosterone levels below 20 ng/dL should be achieved for better treatment results. This might be achieved either by using long term ADT, total androgen blockage or novel antiandrogen treatments. Compared to similar studies previously described our patient have a homogenous treatment protocol and follow up duration is longer. All of the patients were treated according to our institutional treatment protocol and all received the planned treatment. All the follow ups were carried out at a single center using the same lab. Thus, all patients seem to have more homogenous treatment and follow up.
In this study we demonstrated that castrate testosterone level of less than 20 ng/dl achieved after primary RT plus ADT is associated with better BRFS. Using castrate cut off value of 20 ng/dL is better in estimating the BRFS compared to 50 ng/dL. Further studies using current standard of care of high dose IMRT and longer ADT duration might support these findings.