The prognostic impact of serum testosterone during androgen-deprivation therapy in patients with metastatic prostate cancer and the SRD5A2 polymorphism

Methods for Evaluating the Efficacy of Medical Castration: A Systematic Review

Measuring serum testosterone determination during medical castration is recommended by prostate cancer (PCa) guidelines to assess its efficacy and define castration resistance. It has been suggested that other biochemical compounds, such as free testosterone or luteinising hormone (LH), could also assess castration efficacy. We aimed to analyse the current evidence for serum biochemical compounds that could be appropriate candidates for evaluating medical castration efficacy. A systematic review was conducted after two investigators independently searched the literature in the PubMed, Cochrane Library, and EMBASE databases published between January 1980 and February 2023. Their searches used the medical subject headings 'prostatic neoplasms', 'testosterone and androgen antagonists', 'gonadotropin-releasing hormone/analogues and derivatives', 'free testosterone', and 'luteinising hormone'. Studies were selected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria, and their eligibility was based on the Participants, Intervention, Comparator, and Outcome strategy. The search was limited to original articles published in English. Among the 6599 initially identified titles, 15 original studies analysing the clinical impact of serum testosterone levels in PCa patients undergoing androgen deprivation therapy (ADT) were selected for evidence acquisition. The risk of bias in individual studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. All selected studies used immunoassays to measure serum testosterone, although only methods based on liquid or gas chromatography and mass spectrometry are recommended to measure low testosterone concentrations. The reported series were not uniform in clinical stage, ADT types, and the time or number of serum testosterone measurements. Only some studies found low serum testosterone levels (<20 or <32 ng/dL) associated with greater survival free of biochemical progression and castration resistance. We conclude that little current evidence justifies the measurement of serum testosterone during ADT using no appropriate methods. No reported longitudinal studies have examined the clinical impact of serum testosterone measured using liquid chromatography with tandem mass spectrometry (LC-MSMS), free testosterone, or LH in PCa patients undergoing medical castration. We conclude that well-designed longitudinal studies examining the clinical impact of serum testosterone measured with LC-MSMS, serum-free testosterone, and LH on biochemical progression and castration resistance in PCa patients undergoing neo-adjuvant castration in radiation therapy or continuous castration are needed.

A Phase II Trial of Abiraterone With Dutasteride for Second-Generation Antiandrogen- and Chemotherapy-Naïve Patients With Castration-Resistant Prostate Cancer

The development of a novel therapy to overcome primary and acquired resistance to abiraterone is an unmet need. This study aimed to evaluate the efficacy and safety of adding 5α-reductase inhibitor dutasteride to abiraterone, explore proof of concept, and identify candidates suitable for combination therapy. This phase II, single-arm, and open-label study enrolled second-generation antiandrogen- and chemotherapy-naïve patients with castration-resistant prostate cancer. Patients received abiraterone and prednisolone for 4 weeks, followed by adding dutasteride. The primary end point was a 50% prostate-specific antigen response rate. Serum concentrations of abiraterone and its metabolites as well as HSD3B1 and SRD5A2 genotypes were measured. The association between drug metabolism and genotypes and their impact on the efficacy of combination therapy were assessed. Among 21 patients, 18 (85.7%) achieved ≥50% PSA reduction. Median time to treatment failure was not reached during the median follow-up of 15.4 months. No patients experienced grade ≥3 adverse events. Although dutasteride reduced serum 3-keto-5α-abiraterone concentrations, higher serum 3-keto-5α-abiraterone concentrations on combination therapy were associated with a shorter time to treatment failure. HSD3B1 and SRD5A2 genotypes were associated with serum Δ4-abiraterone and 3-keto-5α-abiraterone concentrations before adding dutasteride, respectively. Time to treatment failure was longer in patients with homozygous wild-type HSD3B1, but comparable between those with the SRD5A2 genotype. The promising outcomes of this study warrant further investigation of combination therapy in a randomized trial. Stratification by HSD3B1 and SRD5A2 genetic profiles might identify patients suitable for combination therapy.

Mass spectrometry redefines optimal testosterone thresholds in prostate cancer patients undergoing androgen deprivation therapy

BACKGROUND

Androgen deprivation therapy (ADT) is the standard of care for prostate cancer treatment. Studies suggest that patients with testosterone levels below 0.7 nM have a longer time to castration resistance. Using the most accurate testosterone measurement method, namely mass spectrometry (MS), we sought to determine if a lower testosterone level under ADT could be associated with longer time to castration resistance.

METHODS

This retrospective study included 138 prostate cancer patients undergoing noncurative continuous ADT for which we had access to testosterone measurements assessed by MS. For 108 samples, paired immunoassays (IA) testosterone measurement was available. Primary outcome was time to castration-resistant prostate cancer (CRPC). The Contal and O'Quigley method was used to determine the optimal testosterone castration cut-off point considering the outcome and time-to-event variables. Relationship between testosterone levels assessed either by IA or MS and time to CRPC was evaluated using Cox regression.

RESULTS

Mean testosterone level was 0.370 nM by IA and 0.275 nM as assessed by MS. The optimal testosterone cut-off point identified to predict time to CRPC was of 0.705 nM for IA and of 0.270 nM for MS. While no significant difference for time to CRPC was found between patients showing IA testosterone level ≥0.705 nM versus <0.705 nM (hazard ratio [HR]: 1.579; 95% confidence interval [CI]: 0.908-2.745), patients with MS testosterone ≥0.270 nM had an increased risk of progression to CRPC compared to MS testosterone <0.270 nM in univariate (HR: 1.717; 95% CI: 1.160-2.541) and multivariate analysis (HR: 1.662; 95% CI: 1.043-2.648).

CONCLUSIONS

The higher sensitivity of MS testosterone measurement methods allows the identification of a lower castration threshold and leads to early identification of patients more likely to progress to CRPC. These patients would likely benefit from treatment intensification by androgen receptor axis-targeted therapies to delay disease progression.

Circulating and Intratumoral Adrenal Androgens Correlate with Response to Abiraterone in Men with Castration-Resistant Prostate Cancer

PURPOSE

In metastatic castration-resistant prostate cancer (mCRPC) low serum androgens prior to starting abiraterone acetate (AA) is associated with more rapid progression. We evaluated the effect of AA on androgens in castration-resistant prostate cancer (CRPC) metastases and associations of intratumoral androgens with response.

EXPERIMENTAL DESIGN

We performed a phase II study of AA plus prednisone in mCRPC. The primary outcome was tissue testosterone at 4 weeks. Exploratory outcomes were association of steroid levels and genomic alterations with response, and escalating AA to 2,000 mg at progression.

RESULTS

Twenty-nine of 30 men were evaluable. Testosterone in metastatic biopsies became undetectable at 4 weeks (P < 0.001). Serum and tissue dehydroepiandrosterone sulfate (DHEAS) remained detectable in many patients and was not increased at progression. Serum and tissue DHEAS in the lowest quartile (pretreatment), serum DHEAS in the lowest quartile (4 weeks), and undetectable tissue DHEAS (on-therapy) associated with rapid progression (20 vs. 48 weeks, P = 0.0018; 20 vs. 52 weeks, P = 0.0003; 14 vs. 40 weeks, P = 0.0001; 20 vs. 56 weeks, P = 0.02, respectively). One of 16 men escalating to 2,000 mg had a 30% PSA decline; 13 developed radiographic progression by 12 weeks. Among patients with high serum DHEAS at baseline, wild-type (WT) PTEN status associated with longer response (61 vs. 33 weeks, P = 0.02).

CONCLUSIONS

Low-circulating adrenal androgen levels are strongly associated with an androgen-poor tumor microenvironment and with poor response to AA. Patients with CRPC with higher serum DHEAS levels may benefit from dual androgen receptor (AR)-pathway inhibition, while those in the lowest quartile may require combinations with non-AR-directed therapy.

The association between missense polymorphisms in SRD5A2 and HSD3B1 and treatment failure with abiraterone for castration-resistant prostate cancer

Missense polymorphism in HSD3B1, encoding 3β-hydroxysteroid dehydrogenase-1, was associated with outcome after abiraterone treatment. Other androgen-metabolizing enzymes may be involved in therapeutic effect in abiraterone. In this study, we investigated the significance of polymorphisms in genes involved in androgen and abiraterone metabolisms in prostate cancer patients treated with abiraterone. A total of 99 Japanese male castration-resistant prostate cancer patients treated with abiraterone between 2014 and 2018 were included. Genomic DNA was obtained from whole blood samples, and genotyping on SRD5A2 (rs523349), CYP17A1 (rs743572), CYP17A1 (rs2486758), and AKR1C3 (rs12529) was performed by PCR-based technique. Among the 99 patients, 32 (32.3%), 49 (49.5%), and 18 patients (18.2%) carried GG, GC, and CC alleles in SRD5A2, respectively. CC allele was associated with lower risk of treatment failure (hazard ratio, 0.43; 95% confidence interval, 0.20-0.87; P = 0.017) on multivariate analyses, compared with GG/GC alleles. In the combination model using HSD3B1 and SRD5A2 polymorphisms, compared with the combination of AA in HSD3B1 and GG/GC in SRD5A2, other combinations were associated with lower risk of treatment failure (hazard ratio, 0.34; 95% confidence interval, 0.17-0.62; P = 0.0003) on multivariate analyses. This study showed that SRD5A2 genetic variation was associated with the risk of treatment failure in abiraterone. Combinational use of genetic variation in HSD3B1 with SRD5A2 genetic variation augmented the ability of prognostic stratification.

Epidemiology and genomics of prostate cancer in Asian men

Prostate cancer is a global health problem, but incidence varies considerably across different continents. Asia is traditionally considered a low-incidence area, but the incidence and mortality of prostate cancer have rapidly increased across the continent. Substantial differences in epidemiological features have been observed among different Asian regions, and incidence, as well as mortality-to-incidence ratio, is associated with the human development index. Prostate cancer mortality decreased in Japan and Israel from 2007 to 2016, but mortality has increased in Thailand, Kyrgyzstan and Uzbekistan over the same period. Genomic analyses have shown a low prevalence of ERG oncoprotein in the East Asian population, alongside a low rate of PTEN loss, high CHD1 enrichments and high FOXA1 alterations. Contributions from single-nucleotide polymorphisms to prostate cancer risk vary with ethnicity, but germline mutation rates of DNA damage repair genes in metastatic prostate cancer are comparable in Chinese and white patients from the USA and UK. Pharmacogenomic features of testosterone metabolism might contribute to disparities seen in the response to androgen deprivation between East Asian men and white American and European men. Overall, considerable diversity in epidemiology and genomics of prostate cancer across Asia defines disease characteristics in these populations, but studies in this area are under-represented in the literature. Taking into account this intracontinental and intercontinental heterogeneity, translational studies are required in order to develop ethnicity-specific treatment strategies.

A four-gene signature associated with clinical features can better predict prognosis in prostate cancer

Prostate cancer (PCa) is one of the most deadly urinary tumors in men globally, and the 5‐year over survival is poor due to metastasis of tumor. It is significant to explore potential biomarkers for early diagnosis and personalized therapy of PCa. In the present study, we performed an integrated analysis based on multiple microarrays in the Gene Expression Omnibus (GEO) dataset and obtained differentially expressed genes (DEGs) between 510 PCa and 259 benign issues. The weighted correlation network analysis indicated that prognostic profile was the most relevant to DEGs. Then, univariate and multivariate COX regression analyses were conducted and four prognostic genes were obtained to establish a four‐gene prognostic model. And the predictive effect and expression profiles of the four genes were well validated in another GEO dataset, The Cancer Genome Atlas and the Human Protein Atlas datasets. Furthermore, combination of four‐gene model and clinical features was analyzed systematically to guide the prognosis of patients with PCa to a largest extent. In summary, our findings indicate that four genes had important prognostic significance in PCa and combination of four‐gene model and clinical features could achieve a better prediction to guide the prognosis of patients with PCa.

Polymorphisms in androgen metabolism genes with serum testosterone levels and prognosis in androgen-deprivation therapy

OBJECTIVE

Androgen metabolism is a key component in therapeutic resistance to androgen deprivation therapy (ADT). This study aimed to reveal the significance of genetic polymorphisms in genes involved in androgen metabolism, including CYP17A1, AKR1C3, and HSD17B, on serum testosterone levels during ADT, as well as the prognosis of men undergoing ADT for metastatic prostate cancer (CaP).

MATERIALS AND METHODS

This study included 104 Japanese patients with metastatic CaP, for whom serum testosterone data during ADT were available for 80 patients. The association of CYP17A1 (rs743572), AKR1C3 (rs12529), HSD17B1 (rs605059), HSD17B3 (rs2066479), and HSD17B4 (rs7737181) with serum testosterone levels during ADT and prognosis (progression-free survival and overall survival) was examined. Enzymatic activity in AKR1C3 H5Q was examined using recombinant protein.

RESULTS

Homozygous wild-type (GG allele; median [interquartile range], 12.0 ng/ml [8.0-19.0 ng/ml]) AKR1C3 rs12529 was associated with higher serum testosterone levels during ADT compared with variant-type (GC/CC alleles; median [interquartile range], 9.0 ng/ml [6.4-10.8 ng/ml]). Consistently, variant-type (GC/CC alleles) AKR1C3 rs12529 showed significantly lower risk of progression (hazard ratio [95% confidence interval], 0.47 [0.24-0.96], P = 0.039) compared with homozygous wild-type (GG allele) on multivariate analysis. Meanwhile, other genetic variations were associated with neither serum testosterone during ADT nor prognosis. Enzyme activity of wild-type AKR1C3 was comparable to the H5Q mutant.

CONCLUSIONS

Taken together, this study demonstrated that AKR1C3 polymorphism, which was associated with serum testosterone levels during ADT, may be a prognostic factor of the progression to castration-resistant prostate cancer in Japanese men with metastatic CaP.

Germline polymorphisms associated with impaired survival outcomes and somatic tumor alterations in advanced prostate cancer

INTRODUCTION

Germline variants in androgen metabolism genes may influence clinical response to androgen deprivation therapy (ADT) in advanced prostate cancer. We sought to investigate the prognostic significance of germline variants in androgen metabolism genes with respect to overall survival (OS) after ADT, and to associate germline variants with tumor genomic features.

METHODS

Germline and somatic whole-genome sequencing (WGS) data were evaluated in a cohort of 101 men with metastatic castration-resistant prostate cancer (mCRPC). Survival analyses were performed to identify polymorphisms associated with impaired OS after primary ADT. Germline variants found to be prognostic of OS were associated with tumor somatic DNA-sequence alterations based on WGS performed on paired metastasis biopsies from the same 101 patients. Gene set enrichment analysis was performed based on tumor RNA-sequencing data to identify genomic pathways differentially expressed in patients with germline variants.

RESULTS

A comprehensive literature review identified 17 candidate polymorphisms in nine androgen metabolism genes that have been previously shown to have an association with response to ADT in prostate cancer. Of these, the variant rs1856888 allele located 13 kb upstream of HSD3B1 was found to be significantly associated with impaired OS (P = 0.029). Variant rs1856888 was commonly co-inherited with the well-characterized HSD3B1(1245A>C) polymorphism, and there was a trend toward shorter median OS in patients with HSD3B1(1245A>C) compared with homozygous wild-type patients (P = 0.052). While HSD3B1 germline variants were not associated with common somatic tumor DNA alterations, they were associated with increased tumor expression of cell proliferation and cell cycle genes.

CONCLUSIONS

This study presents a comprehensive assessment of germline variants in androgen metabolism genes and highlights HSD3B1 polymorphisms as prognostic of OS after ADT and associated with an aggressive gene expression tumor profile in mCRPC.

Relationship between body composition and hormone sensitivity for androgen deprivation therapy in patients with metastatic prostate cancer

Background

To evaluate the relationship between body composition and the oncological outcome of androgen deprivation therapy (ADT), we investigated whether body composition features including the psoas muscle may be predictive factors of ADT.

Methods

This study enrolled patients with hormone-naïve metastatic prostate cancer who were treated with primary ADT from April 1996 to November 2013 at Kyushu University Hospital and who underwent a computed tomography scan before primary ADT for calculating body fat percentage, psoas muscle ratio (psoas muscle, cm³/height, cm), and body mass index.

Results

Of the 178 patients enrolled, 60 patients died during follow-up. Median follow-up was 32 months, and progression-free survival and overall survival (OS) were 28 and 80 months, respectively. Multivariate analysis revealed that the psoas muscle ratio was correlated with OS (hazard ratio: 0.448; 95% confidence interval = 0.206–0.922; p = 0.028).

Conclusions

This study demonstrated that higher psoas muscle ratio predicts longer OS among patients with nonlocalized prostate cancer treated with primary ADT.

Aging and the Male Reproductive System

This narrative review presents an overview of current knowledge on fertility and reproductive hormone changes in aging men, the factors driving and modulating these changes, their clinical consequences, and the benefits and risks of testosterone (T) therapy. Aging is accompanied by moderate decline of gamete quality and fertility. Population mean levels show a mild total T decline, an SHBG increase, a steeper free T decline, and a moderate LH increase with important contribution of comorbidities (e.g., obesity) to these changes. Sexual symptoms and lower hematocrit are associated with low T and are partly responsive to T therapy. The relationship of serum T with body composition and metabolic health is bidirectional; limited beneficial effects of T therapy on body composition have only marginal effects on metabolic health and physical function. Skeletal changes are associated primarily with estradiol and SHBG. Cognitive decline is not consistently linked to low T and is not improved by T therapy. Although limited evidence links moderate androgen decline with depressive symptoms, T therapy has small beneficial effects on mood, depressive symptoms, and vitality in elderly patients with low T. Suboptimal T (and/or DHT) has been associated with increased risk of stroke, but not of ischemic heart disease, whereas an association with mortality probably reflects that low T is a marker of poor health. Globally, neither severity of clinical consequences attributable to low T nor the nature and magnitude of beneficial treatment effects justify the concept of some broadly applied "T replacement therapy" in older men with low T. Moreover, long-term safety of T therapy is not established.

The impact of genetic polymorphism on CYP19A1 in androgen-deprivation therapy among Japanese men

PURPOSE

Inadequate suppression of testosterone during androgen-deprivation therapy impairs its efficacy. This study investigated the significance of genetic polymorphism in CYP19A1, which encodes aromatase that catalyzes androgens into estrogens, among men treated with primary ADT for metastatic prostate cancer.

METHODS

This study included 80 Japanese patients with metastatic prostate cancer whose serum testosterone levels during ADT were available. The association of CYP19A1 gene polymorphism (rs1870050) with clinicopathological parameters including serum testosterone levels during ADT as well as progression-free survival and overall survival was examined.

RESULTS

Serum testosterone levels during ADT of men carrying homozygous wild-type (AA) in the CYP19A1 gene [median (interquartile range); 11.6 (8.3-20.3) ng/dl] were higher than those in men carrying the heterozygous/homozygous variant (AC/CC) [median (interquartile range); 10.0 (6.4-12.8) ng/dl]. When adjusted by Gleason score, initial PSA, M-stage and serum testosterone level during ADT, heterozygous/homozygous variant (AC/CC) in the CYP19A1 gene was associated with a lower risk of progression to castration resistance [hazard ratio (95% confidence interval), 0.53 [0.29-0.92], p = 0.025], but not to any-cause death [hazard ratio (95% confidence interval), 0.74 [0.36-1.49], p = 0.40].

CONCLUSIONS

These findings suggest that genetic variation in CYP19A1 (rs1870050) might affect the prognosis of patients with metastatic prostate cancer when treated with ADT by regulating serum testosterone levels.

Serum testosterone level as possible predictive marker in androgen receptor axis-targeting agents and taxane chemotherapies for castration-resistant prostate cancer

PURPOSE

Currently, several therapeutic options for castration-resistant prostate cancer (CRPC) are available, for which predictive biomarkers have not been established. Therefore, we aimed to reveal the association between pretreatment serum testosterone level and antitumor outcomes when treated with androgen receptor axis-targeting agents and taxane chemotherapies for CRPC.

PATIENTS AND METHODS

The present study included Japanese patients with metastatic prostate cancer whose serum testosterone levels during androgen-deprivation therapy were available. The antitumor outcomes when treated with enzalutamide, abiraterone, docetaxel, and cabazitaxel with clinicopathological parameters including serum testosterone levels during androgen-deprivation therapy, as well as prognoses including progression-free survival and overall survival, were examined.

RESULTS

Progression-free survival among men with higher serum testosterone level was superior to that among men with lower serum testosterone level when treated with enzalutamide. On the contrary, progression-free survival and overall survival among men with higher serum testosterone level were significantly inferior to those among men with lower serum testosterone level when treated with docetaxel and cabazitaxel, respectively.

CONCLUSIONS

The present study indicated distinct prognostic values of serum testosterone level when treated with androgen receptor axis-targeting agent and taxane chemotherapy for CRPC, suggesting that serum testosterone level may be useful predictive biomarker to navigate the appropriate therapy in patients with CRPC.

Neoadjuvant androgen-deprivation therapy with radical prostatectomy for prostate cancer in association with age and serum testosterone

BACKGROUND

We aimed to identify the candidate prostate cancer patients suitable for neoadjuvant androgen-deprivation therapy (ADT) with radical prostatectomy (RP).

MATERIALS AND METHODS

This study included 711 Japanese patients with clinically localized prostate cancer who were treated with RP between 2000 and 2013. Patients were treated with or without neoadjuvant ADT before RP. The prognostic significance of neoadjuvant ADT on biochemical recurrence (BCR) was analyzed according to various clinicopathological characteristics.

RESULTS

BCR occurred in 186 (26.2%) of 711 patients. The group treated with neoadjuvant ADT showed higher levels of prostate-specific antigen at diagnosis and advanced clinical T-stage, but suppressed pathological T-stage. Neoadjuvant ADT was not associated with the risk of BCR. In subgroup analysis, neoadjuvant ADT was significantly associated with increased BCR in patients aged >65 years [hazard ratio (95% confidence interval), 2.04 (1.13-3.43), P = 0.020]. Among the 53 patients with available serum testosterone levels, neoadjuvant ADT was associated with the risk of BCR according to serum testosterone levels.

CONCLUSION

This study demonstrated that neoadjuvant ADT showed potential deleterious effects in older patients and patients with lower serum testosterone levels, while a possible improved prognosis in patients with high serum testosterone levels treated with neoadjuvant ADT was suggested, warranting further exploration.

Sex steroids in the tumor microenvironment and prostate cancer progression

Prostate cancer is uniquely dependent on androgens. Despite years of research on the relationship between androgens and prostate cancer, many questions remain as to the biological effects of androgens and other sex steroids during prostate cancer progression. This article reviews the clinical and basic research on the influence of sex steroids such as androgens, estrogens and progesterone within the prostate tumor microenvironment on the progression of prostate cancer. We review clinical studies to date evaluating serum sex steroids as prognostic biomarkers and discuss their respective biological effects within the prostate tumor microenvironment. We also review the link between genomic alterations and sex steroid levels within prostate tumors. Finally, we highlight the links between sex steroid levels and the function of the immune system within the tumor microenvironment. As the context of treatment of lethal prostate cancer evolves over time, an understanding of this underlying biology remains central to developing optimal treatment approaches.

Gene polymorphisms in antioxidant enzymes correlate with the efficacy of androgen-deprivation therapy for prostate cancer with implications of oxidative stress

Background

Oxidative stress mitigated by antioxidant enzymes is thought to be involved in the progression to castration-resistant prostate cancer (CRPC) during androgen-deprivation therapy (ADT). This study investigated the association between genetic variations in antioxidant enzymes and the efficacy of ADT as well as its biological background.

Patients and methods

The non-synonymous or promoter-locating polymorphisms of antioxidant enzymes were examined as well as the time to CRPC progression and overall survival in 104 and 92 patients treated with ADT for metastatic and non-metastatic prostate cancer, respectively. In addition, intracellular reactive oxygen species and expression levels of antioxidant enzymes were examined in castration-resistant and enzalutamide-resistant cells.

Results

In metastatic prostate cancer, the AG/GG allele in GSTM3 rs7483 and CT/TT allele in CAT rs564250 were associated with a significantly lower risk of progression to CRPC and all-cause death compared with homozygotes of the major AA allele (hazard ratio [HR]; [95% confidence interval (CI)], 0.55 [0.34-0.86], P = 0.0086) and CC allele (HR; [95% CI], 0.48 [0.24-0.88], P = 0.016), respectively. On multivariate analyses, only GSTM3 rs7483 was associated with significant progression risk (AG/GG versus AA; HR; [95% CI], 0.45 [0.25-0.79], P = 0.0047) even after Bonferroni adjustment. In non-metastatic prostate cancer, the AG/GG allele in GSTM3 rs7483 was associated with a significantly lower risk of progression to CRPC (HR; [95% CI], 0.35 [0.10-0.93], P = 0.034) and all-cause death (HR; [95% CI], 0.26 [0.041-0.96], P = 0.043) compared with the AA allele. Intracellular reactive oxygen species levels were increased, accompanied with augmented GSTM3 expression in both castration-resistant and enzalutamide-resistant cells.

Conclusions

Differential activity of antioxidant enzymes caused by the polymorphism in GSTM3 may contribute to resistance to hormonal therapy through oxidative stress. The GSTM3 rs7483 polymorphism may be a promising biomarker for prostate cancer patients treated with ADT.

Testosterone monitoring for men with advanced prostate cancer: Review of current practices and a survey of Canadian physicians

Androgen-deprivation therapy (ADT) is a standard of care in the treatment of advanced prostate cancer; however, testosterone monitoring practices for men undergoing ADT vary across Canada. Although a testosterone level of 1.7 nmol/L or lower has historically been defined as the accepted castrate level, newer assays with improved sensitivity have shown that both medical and surgical castration can suppress testosterone levels to below 0.7 nmol/L. This review explores the evidence supporting a redefinition of the castrate testosterone level as 0.7 nmol/L or lower, and presents results of a survey of testosterone monitoring practices among 153 Canadian urologists, uro-oncologists, and radiation oncologists who manage the treatment of men with hormone-sensitive prostate cancer.

Gene Polymorphism-related Individual and Interracial Differences in the Outcomes of Androgen Deprivation Therapy for Prostate Cancer

Among patients with prostate cancer, the prognosis after androgen deprivation therapy differs significantly among individuals and among races; however, the reasons underlying these differences are poorly understood. Several single nucleotide polymorphisms in genes associated with prostate cancer progression or castration resistance might serve as the host factor that influences prognosis and, thus, accounts for these individual and racial gaps in treatment outcomes. Accordingly, single nucleotide polymorphisms associated with treatment outcomes could be used as predictive and/or prognostic biomarkers for patient stratification and to identify personalized treatment and follow-up protocols. The present review has summarized the genetic polymorphisms that have been reported to associate with androgen deprivation therapy outcomes among patients with prostate cancer and compared the allele frequencies among different ethnic groups.

Maximal testosterone suppression in the management of recurrent and metastatic prostate cancer

INTRODUCTION

Testosterone suppression, or androgen-deprivation therapy (ADT), is an established treatment for recurrent and metastatic prostate cancer (PCa). Based on the accuracy and sensitivity of early assays (c. 1960-1970), the castrate testosterone level was set at ≤1.7 nmol/l. Improved sensitivity of testosterone assays shows that both surgical and medical castration can achieve levels <0.7 nmol/l. However, the clinical implications and importance of maximum testosterone suppression remains a subject of controversy. This evidence-based review assesses prospective and retrospective clinical data, linking maximum suppression of testosterone with improved outcomes from ADT.

METHODS

PubMed and conference proceedings were searched for studies assessing the impact of low testosterone on clinical outcomes from ADT. The key search terms included combinations of prostate cancer and testosterone, predictive/prognostic, and androgen deprivation. Results were limited to studies investigating the relationship between testosterone levels and clinical outcomes.

RESULTS

Both prospective and retrospective data support a relationship between testosterone levels below the historical standard of 1.7 nmol/l and improved outcomes. Eight studies showed significant improvements in survival-related outcomes, with the majority of data supporting a testosterone level cutoff of ≤0.7 nmol/l.

CONCLUSIONS

Tracking both testosterone and prostate-specific antigen (PSA) levels has significant clinical benefits, and the serum testosterone threshold of ≤0.7 nmol/l is a practical goal. The relative levels of testosterone and PSA may indicate continued hormone responsiveness or progression toward castration-resistant prostate cancer (CRPC) and should, therefore, inform treatment strategy. Standardization of assay methods and clinical coordination to facilitate widespread access to state-of the art laboratory equipment is necessary to ensure accurate decision-making.