Retrospective Evaluation Reveals That Long-term Androgen Deprivation Therapy Improves Cause-Specific and Overall Survival in the Setting of Dose-Escalated Radiation for High-Risk Prostate Cancer

Significance of androgen-deprivation therapy for intermediate- and high-risk prostate cancer treated with high-dose radiotherapy: A literature review

The real-world benefits of adding androgen-deprivation therapy (ADT) and its optimal duration when combined with current standard high-dose radiation therapy (RT) remain unknown. We aimed to assess the efficacy of and toxicities associated with ADT in the setting of combination with high-dose RT for intermediate-risk (IR) and high-risk (HR) prostate cancer (PCa). This article is a modified and detailed version of the commentary on Clinical Question 8 described in the Japanese Clinical Practice Guidelines for Prostate Cancer (ver. 2023). A qualitative systematic review was performed according to the Minds Guide. All relevant published studies between September 2010 and August 2020, which assessed the outcomes of IR or HR PCa treated with high-dose RT, were screened using two databases (PubMed and ICHUSHI). A total of 41 studies were included in this systematic review, mostly consisting of retrospective studies (N = 34). The evidence basically supports the benefit of adding ADT to high-dose RT to improve tumor control. Regarding IR populations, many studies suggested the existence of a subgroup for which adding ADT had no impact on either overall survival or the BF-free duration. On the other hand, regarding HR populations, several studies suggested the positive impact of adding ADT for ≥1 year on overall survival. Adding ADT increases not only the risk of sexual dysfunction but also that of cardiovascular toxicities or bone fracture. Although the benefit of adding ADT was basically suggested for both IR and HR populations, further investigations are warranted to identify subgroups of patients for whom ADT has no benefit, as well as the appropriate duration of ADT for those who do derive benefit.

Japanese clinical practice guidelines for prostate cancer 2023

This fourth edition of the Japanese Clinical Practice Guidelines for Prostate Cancer 2023 is compiled. It was revised under the leadership of the Japanese Urological Association, with members selected from multiple academic societies and related organizations (Japan Radiological Society, Japanese Society for Radiation Oncology, the Department of EBM and guidelines, Japan Council for Quality Health Care (Minds), Japanese Society of Pathology, and the patient group (NPO Prostate Cancer Patients Association)), in accordance with the Minds Manual for Guideline Development (2020 ver. 3.0). The most important feature of this revision is the adoption of systematic reviews (SRs) in determining recommendations for 14 clinical questions (CQs). Qualitative SRs for these questions were conducted, and the final recommendations were made based on the results through the votes of 24 members of the guideline development group. Five algorithms based on these results were also created. Contents not covered by the SRs, which are considered textbook material, have been described in the general statement. In the general statement, a literature search for 14 areas was conducted; then, based on the general statement and CQs of the Japanese Clinical Practice Guidelines for Prostate Cancer 2016, the findings revealed after the 2016 guidelines were mainly described. This article provides an overview of these guidelines.

Degarelix as a neoadjuvant hormonal therapy for acute urinary tract toxicity associated with external beam radiotherapy for intermediate- and high-risk prostate cancer: a propensity score matched analysis

BACKGROUND

In prostate cancer treatment, lower urinary tract symptoms significantly improve with luteinizing hormone-releasing hormone antagonists use compared with agonists. However, it is unclear whether luteinizing hormone-releasing hormone antagonists can decrease acute urinary tract toxicity during external beam radiotherapy. This study aimed to assess whether luteinizing hormone-releasing hormone antagonists used as neoadjuvant therapy reduced acute urinary tract toxicity during external beam radiotherapy compared with luteinizing hormone-releasing hormone agonists.

METHODS

The study included 78 patients who underwent intensity-modulated radiation therapy for intermediate- and high-risk prostate cancer between April 2013 and January 2020. Irradiation was initiated after 3-6 months of neoadjuvant therapy. Androgen deprivation therapy was given to the intermediate-risk group for 6 months and the high-risk group for 2-3 years. The European Organization for Research and Treatment of Cancer/Radiation Therapy Oncology Group toxicity grading scale was used to evaluate the urinary tract system toxicity. Relevant clinical factors were used in matching patients based on propensity scores to enable comparison between the groups.

RESULTS

Each group had 27 matched patients. There was no reduction in urinary tract toxicity with the use of luteinizing hormone-releasing hormon antagonists (P = 0.624). For patients with an International Prostate Symptom Score of ≥11 at the start of treatment, 18 patients in each group were matched. Significantly lower scores were observed in the luteinizing hormone-releasing hormon antagonist group (P = 0.041).

CONCLUSIONS

Luteinizing hormone-releasing hormon antagonists may reduce acute urinary tract toxicity during prostate cancer external beam radiotherapy compared with luteinizing hormone-releasing hormon agonists, in particular in patients with moderate to severe symptoms at the start of treatment.

Benefits and Risks of Primary Treatments for High-risk Localized and Locally Advanced Prostate Cancer: An International Multidisciplinary Systematic Review

CONTEXT

The optimal treatment for men with high-risk localized or locally advanced prostate cancer (PCa) remains unknown.

OBJECTIVE

To perform a systematic review of the existing literature on the effectiveness of the different primary treatment modalities for high-risk localized and locally advanced PCa. The primary oncological outcome is the development of distant metastases at ≥5 yr of follow-up. Secondary oncological outcomes are PCa-specific mortality, overall mortality, biochemical recurrence, and need for salvage treatment with ≥5 yr of follow-up. Nononcological outcomes are quality of life (QoL), functional outcomes, and treatment-related side effects reported.

EVIDENCE ACQUISITION

Medline, Medline In-Process, Embase, and the Cochrane Central Register of Randomized Controlled Trials were searched. All comparative (randomized and nonrandomized) studies published between January 2000 and May 2019 with at least 50 participants in each arm were included. Studies reporting on high-risk localized PCa (International Society of Urologic Pathologists [ISUP] grade 4-5 [Gleason score {GS} 8-10] or prostate-specific antigen [PSA] >20 ng/ml or ≥ cT2c) and/or locally advanced PCa (any PSA, cT3-4 or cN+, any ISUP grade/GS) or where subanalyses were performed on either group were included. The following primary local treatments were mandated: radical prostatectomy (RP), external beam radiotherapy (EBRT) (≥64 Gy), brachytherapy (BT), or multimodality treatment combining any of the local treatments above (±any systemic treatment). Risk of bias (RoB) and confounding factors were assessed for each study. A narrative synthesis was performed.

EVIDENCE SYNTHESIS

Overall, 90 studies met the inclusion criteria. RoB and confounding factors revealed high RoB for selection, performance, and detection bias, and low RoB for correction of initial PSA and biopsy GS. When comparing RP with EBRT, retrospective series suggested an advantage for RP, although with a low level of evidence. Both RT and RP should be seen as part of a multimodal treatment plan with possible addition of (postoperative) RT and/or androgen deprivation therapy (ADT), respectively. High levels of evidence exist for EBRT treatment, with several randomized clinical trials showing superior outcome for adding long-term ADT or BT to EBRT. No clear cutoff can be proposed for RT dose, but higher RT doses by means of dose escalation schemes result in an improved biochemical control. Twenty studies reported data on QoL, with RP resulting mainly in genitourinary toxicity and sexual dysfunction, and EBRT in bowel problems.

CONCLUSIONS

Based on the results of this systematic review, both RP as part of multimodal treatment and EBRT + long-term ADT can be recommended as primary treatment in high-risk and locally advanced PCa. For high-risk PCa, EBRT + BT can also be offered despite more grade 3 toxicity. Interestingly, for selected patients, for example, those with higher comorbidity, a shorter duration of ADT might be an option. For locally advanced PCa, EBRT + BT shows promising result but still needs further validation. In this setting, it is important that patients are aware that the offered therapy will most likely be in the context a multimodality treatment plan. In particular, if radiation is used, the combination of local with systemic treatment provides the best outcome, provided the patient is fit enough to receive both. Until the results of the SPCG15 trial are known, the optimal local treatment remains a matter of debate. Patients should at all times be fully informed about all available options, and the likelihood of a multimodal approach including the potential side effects of both local and systemic treatment.

PATIENT SUMMARY

We reviewed the literature to see whether the evidence from clinical studies would tell us the best way of curing men with aggressive prostate cancer that had not spread to other parts of the body such as lymph glands or bones. Based on the results of this systematic review, there is good evidence that both surgery and radiation therapy are good treatment options, in terms of prolonging life and preserving quality of life, provided they are combined with other treatments. In the case of surgery this means including radiotherapy (RT), and in the case of RT this means either hormonal therapy or combined RT and brachytherapy.

Combined Androgen Blockade in Localized Prostate Cancer Treated With Definitive Radiation Therapy

BACKGROUND

The addition of androgen deprivation therapy to radiation therapy (RT) improves survival in patients with intermediate- and high-risk prostate cancer (PCa), but it is not known whether combined androgen blockade (CAB) with a gonadotropin-releasing hormone agonist (GnRH-A) and a nonsteroidal antiandrogen improves survival over GnRH-A monotherapy.

METHODS

This study evaluated patients with intermediate- and high-risk PCa diagnosed in 2001 through 2015 who underwent RT with either GnRH-A alone or CAB using the Veterans Affairs Informatics and Computing Infrastructure. Associations between CAB and prostate cancer-specific mortality (PCSM) and overall survival (OS) were determined using multivariable regression with Fine-Gray and multivariable Cox proportional hazards models, respectively. For a positive control, the effect of long-term versus short-term GnRH-A therapy was tested.

RESULTS

The cohort included 8,423 men (GnRH-A, 4,529; CAB, 3,894) with a median follow-up of 5.9 years. There were 1,861 deaths, including 349 resulting from PCa. The unadjusted cumulative incidences of PCSM at 10 years were 5.9% and 6.9% for those receiving GnRH-A and CAB, respectively (P=.16). Compared with GnRH-A alone, CAB was not associated with a significant difference in covariate-adjusted PCSM (subdistribution hazard ratio [SHR], 1.05; 95% CI, 0.85-1.30) or OS (hazard ratio, 1.02; 95% CI, 0.93-1.12). For high-risk patients, long-term versus short-term GnRH-A therapy was associated with improved PCSM (SHR, 0.74; 95% CI, 0.57-0.95) and OS (SHR, 0.82; 95% CI, 0.73-0.93).

CONCLUSIONS

In men receiving definitive RT for intermediate- or high-risk PCa, CAB was not associated with improved PCSM or OS compared with GnRH alone.

Is androgen deprivation therapy for prostate cancer associated with cardiovascular disease? A meta-analysis and systematic review

BACKGROUND

Androgen deprivation therapy (ADT) is widely being applied in men who suffered from prostate cancer. Whether androgen deprivation therapy (ADT) is associated with an increased risk of developing cardiovascular-related disease is poorly defined.

OBJECTIVES

The aim of the present meta-analysis is to explore the relationship between ADT and the risk of cardiac events. MATERIALS AND METHODS: For this systematic review and meta-analysis, we searched databases from inception to April 2019 for randomized controlled trials (RCT) or observational studies that reported data on ADT administration and cardiac event incidence. The connection was evaluated through estimating relative risk ratio (RR) and 95% confidence intervals (CIs).

RESULTS

A significantly increased acute myocardial infarction (AMI) was detected in the ADT group compared with the control group (RR = 1.19, 95% confidence interval (CI), 1.02-1.39, P < .05). A significant difference between cardiovascular disease (CVD) and ADT was also observed, with summary RR = 1.25, 95% CI, 1.11-1.40, P < .05. Furthermore, our study also suggested ADT was not related to increased incidence of sudden cardiac death (SCD) (RR = 1.13, 95% CI, 0.92-1.38, P = .24); AMI and CVD were not connected with the duration of ADT (AMI: RR = 1.31; 95% CI, 0.66-2.63, P = .44, for > 5 year group; CVD: RR = 1.12, 95% CI, 0.97-1.30, P = .12, for > 5 year group). In addition, the RR for risk of CVD was 1.28 (95% CI, 1.01-1.62, P < .05) for men with PCa on new hormonal agents.

DISCUSSION

Various ADT modalities have different impact on cardiovascular disease risk in different level. Long-term application of ADT is not associated with increased risk of AMI and CVD. Both abiraterone and enzalutamide could significantly increase the incidence of cardiac events in patients who suffered from prostate cancer. Cautions and periodic cardiovascular elevation are necessary for patients before the ADT starting.

CONCLUSIONS

Androgen deprivation therapy is associated with increased risk of AMI, CHD, in contrast, this association is not detected in SCD.

Impact of androgen-deprivation therapy on the outcome of dose-escalation prostate cancer radiotherapy without elective pelvic irradiation

The benefit of androgen-deprivation therapy (ADT) in combination with dose-escalated radiotherapy (DERT) for localized prostate cancer has not been determined in randomized studies. In this study, the benefit of ADT was assessed in patients uniformly treated with dose-escalated intensity-modulated radiation therapy (IMRT) to the prostate and seminal vesicles but not pelvis. In all, 419 patients with localized prostate adenocarcinoma underwent definitive IMRT (cumulative dose 78 Gy), with 32.6%, 33.1%, 32.1%, and 2.1% having T1 through T4 disease, respectively, and 51.2% having high-risk disease. ADT was given to 76.1% of patients. With a median follow-up of 60 months, 5-year biochemical failure-free, disease-free, and overall survival rates were 87%, 86%, and 87%, respectively. T stage was an independent predictor of all three rates. Five-year pelvic nodal recurrence rate was 2.9%. ADT improved biochemical failure-free and disease-free survival but not overall survival. ADT showed benefit in high-risk disease but not intermediate-risk disease. Late gastrointestinal and genitourinary toxicities ≥ grade 2 occurred in 11.0% and 6.7%, respectively. In conclusion, DERT with 78 Gy yields good disease control and low rate of pelvic nodal recurrence. ADT improves disease-free survival in patients with high-risk but not intermediate-risk disease.

The use of Hormonal Therapy to Augment Radiation Therapy in Prostate Cancer: An Update

PURPOSE OF REVIEW

Androgen deprivation therapy (ADT) is an important adjunctive therapy to external beam radiation therapy (RT) for the definitive management of prostate cancer. The role of ADT is well-established for locally advanced or high-risk disease in conjunction with standard doses of RT, but less defined for intermediate-risk disease or with dose-escalated RT. The goal of this review is to summarize evidence evaluating the combination of ADT/RT, focusing on recent trials and current controversies as they pertain to the practicing clinician.

RECENT FINDINGS

The benefit of ADT on biochemical control is maintained with dose-escalated RT according to recently reported phase III studies. Furthermore, there is now prospective, randomized evidence to support the addition of ADT to RT in the post-prostatectomy setting. ADT continues to play an important role for prostate cancer patients receiving dose-escalated RT. Future research is needed to identify subgroups most likely to benefit from this combination.

Effects of dose-escalated radiotherapy in combination with long-term androgen deprivation on prostate cancer

OBJECTIVE

We aimed to examine the effects of a dose escalation for prostate cancer patients receiving long-term androgen deprivation therapy (ADT).

METHODS

A retrospective analysis of 605 patients treated with radiotherapy (RT) and long-term ADT (National Comprehensive Cancer Network criteria-defined intermediate-risk, minimum 10 months; high-risk and very-high-risk, minimum 20 months) was performed. The median ADT time was 31 months. Cox's proportional hazards models were used to compare biochemical disease-free survival (bDFS), clinical relapse-free survival (cRFS) and overall survival (OS) between the ≥70, <78 Gy group and 78 Gy group in a univariate analysis and to assess the effects of the dose escalation on bDFS in a multivariate analysis.

RESULTS

After a median follow-up of 70 months, 5-year bDFS was significantly better in the 78 Gy group than in the ≥70, <78 Gy group [96 vs 83%; hazard ratio 3.6 (95% confidence interval 2.2-6.1); p < 0.001]. 5-year cRFS and OS were similar between the two groups. The multivariate analysis showed that RT dose was still an independent prognostic factor of bDFS (p = 0.005).

CONCLUSION

The results of the present study suggest that dose escalations result in significant improvements in bDFS, even when used in combination with long-term ADT. A longer follow-up is needed to clarify the effects of dose escalations on cRFS and OS. Advances in knowledge: It remains unclear whether high-dose RT is necessary for improving the outcomes of patients receiving long-term ADT. The results suggest that dose escalations result in significant improvements in biochemical control.

Dose escalation of external beam radiotherapy for high-risk prostate cancer-Impact of multiple high-risk factor

Objective

To retrospectively investigate the treatment outcomes of external beam radiotherapy with androgen deprivation therapy (ADT) in high-risk prostate cancer in three radiotherapy dose groups.

Methods

Between 1998 and 2013, patients with high-risk prostate cancer underwent three-dimensional conformal radiotherapy or intensity-modulated radiotherapy of 66 Gy, 72 Gy, or 78 Gy with ADT. Prostate-specific antigen (PSA) relapse was defined using the Phoenix definition. PSA relapse-free survival (PRFS) was evaluated in each radiotherapy dose group. Moreover, high-risk patients were divided into H-1 (patients with multiple high-risk factors) and H-2 (patients with a single high-risk factor) as risk subgroups.

Results

Two hundred and eighty-nine patients with a median follow-up period of 77.3 months were analyzed in this study. The median duration of ADT was 10.1 months. Age, Gleason score, T stage, and radiotherapy dose influenced PRFS with statistical significance both in univariate and multivariate analyses. The 4-year PRFS rates in Group-66 Gy, Group-72 Gy and Group-78 Gy were 72.7%, 81.6% and 90.3%, respectively. PRFS rates in the H-1 subgroup differed with statistical significance with an increasing radiotherapy dose having a more favorable PRFS, while PRFS rates in H-2 subgroup did not differ with increase in radiotherapy dose.

Conclusion

Dose escalation for high-risk prostate cancer in combination with ADT improved PRFS. PRFS for patients in the H-1 subgroup was poor, but dose escalation in those patients was beneficial, while dose escalation in the H-2 subgroup was not proven to be effective for improving PRFS.

Clinical outcome and toxicity evaluation of simultaneous integrated boost pelvic IMRT/VMAT at different dose levels combined with androgen deprivation therapy in prostate cancer patients

Background

The role of dose escalation in patients receiving long-term androgen deprivation therapy (ADT) is still a controversial issue. The aim of the current study was to evaluate whether dose escalation for ≥76–80 Gy had any advantage in terms of biochemical disease-free survival (BDFS), distant metastasis-free survival (DMFS), or overall survival outcomes over the dose levels from 70 to <76 Gy.

Patients and methods

The study included a cohort of 24 patients classified with high- and intermediate-risk localized prostate cancer. All patients received ADT, starting at 4–6 months before radiation therapy and continued for a total period of 12–24 months in high-risk patients. The treatment plan was given in two phases. In the first phase, the nodal planning target volume (PTV) and the prostate PTV received 48.6 and 54 Gy, respectively, over 27 fractions. The treatment was applied through intensity-modulated radiation therapy or volumetric modulated arc therapy with a simultaneous integrated boost technique.

Results

More than half of the patients were in T3–T4 stage, 79.1% of the patients were in the high-risk category, and all patients received ADT. The rate of acute grade II gastrointestinal and genitourinary toxicities in all patients were 41.7% and 62.5%, respectively. The rate of freedom from grade II rectal toxicity at 2 years was 89% and 83% for patients treated with dose levels <76 and ≥76 Gy, respectively. The rate of BDFS at 2 years was 90% and 85% for doses <76 and ≥76 Gy, respectively. The DMFS at 2 years was 100% and 76% for dose levels <76 and ≥76 Gy, respectively.

Conclusion

In the current study, there were no significant differences in the BDFS and DMFS between patients treated with a dose of <76 and ≥76 Gy, including elective pelvic lymph nodes irradiation combined with ADT.

High-risk Prostate Cancer Treated With Dose-escalated RT: An Analysis of Hormonal Therapy Use and Duration, and Prognostic Implications of PSA Nadir ≤0.2 to Select Men for Short-term Hormonal Therapy

OBJECTIVES

To determine prognostic factors to select high-risk men receiving dose-escalated radiation therapy (RT) who will have favorable outcomes with short-term (ST) or no androgen deprivation therapy (ADT).

METHODS

Medical records of 458 men treated with definitive RT for high-risk, nonmetastatic prostate cancer at 3 academic referral centers from 1988 to 2009 were examined. Median dose was 76.4 Gy. Men received no ADT (n=105), STADT (<12 mo, n=194), or long-term ADT (LTADT: ≥12 mo, n=160). Univariate and multivariable analysis for freedom from distant metastases (FFDM) and cause-specific survival (CSS) were performed. Median follow-up was 71 months.

RESULTS

Seven-year FFDM was 83% and CSS was 91%. Multivariable analysis demonstrated that prostate-specific antigen (PSA) nadir ≤0.2 (HR=0.36; 95% CI, 0.20-0.64) and Gleason score (GS) were associated with FFDM and CSS (all P<0.05). ADT duration was not associated (P>0.05). Those with PSA nadir ≤0.2 ng/mL had improved outcomes. Men with GS 9 disease did poorly despite a PSA nadir ≤0.2 ng/mL and had improved CSS with LTADT (95% vs. 71%, P<0.05).

CONCLUSIONS

Select men with high-risk disease treated with dose-escalated RT may not require LTADT. In men treated with ADT, PSA nadir ≤0.2 is an independent prognostic factor associated with FFDM and CSS. Men without GS 9 may have acceptable outcomes with STADT if PSA nadir is ≤0.2 ng/mL. Further investigation is necessary to elucidate the role of PSA nadir in determining the optimal length of adjuvant ADT.

Targeted radiosensitization of ETS fusion-positive prostate cancer through PARP1 inhibition

ETS gene fusions, which result in overexpression of an ETS transcription factor, are considered driving mutations in approximately half of all prostate cancers. Dysregulation of ETS transcription factors is also known to exist in Ewing's sarcoma, breast cancer, and acute lymphoblastic leukemia. We previously discovered that ERG, the predominant ETS family member in prostate cancer, interacts with the DNA damage response protein poly (ADP-ribose) polymerase 1 (PARP1) in human prostate cancer specimens. Therefore, we hypothesized that the ERG-PARP1 interaction may confer radiation resistance by increasing DNA repair efficiency and that this radio-resistance could be reversed through PARP1 inhibition. Using lentiviral approaches, we established isogenic models of ERG overexpression in PC3 and DU145 prostate cancer cell lines. In both cell lines, ERG overexpression increased clonogenic survival following radiation by 1.25 (±0.07) fold (mean ± SEM) and also resulted in increased PARP1 activity. PARP1 inhibition with olaparib preferentially radiosensitized ERG-positive cells by a factor of 1.52 (±0.03) relative to ERG-negative cells (P < .05). Neutral and alkaline COMET assays and immunofluorescence microscopy assessing γ-H2AX foci showed increased short- and long-term efficiencies of DNA repair, respectively, following radiation that was preferentially reversed by PARP1 inhibition. These findings were verified in an in vivo xenograft model. Our findings demonstrate that ERG overexpression confers radiation resistance through increased efficiency of DNA repair following radiation that can be reversed through inhibition of PARP1. These results motivate the use of PARP1 inhibitors as radiosensitizers in patients with localized ETS fusion-positive cancers.

Hypoxia-independent downregulation of hypoxia-inducible factor 1 targets by androgen deprivation therapy in prostate cancer

PURPOSE

We explored changes in hypoxia-inducible factor 1 (HIF1) signaling during androgen deprivation therapy (ADT) of androgen-sensitive prostate cancer xenografts under conditions in which no significant change in immunostaining of the hypoxia marker pimonidazole had occurred.

METHODS AND MATERIALS

Gene expression profiles of volume-matched androgen-exposed and androgen-deprived CWR22 xenografts, with similar pimonidazole-positive fractions, were compared. Direct targets of androgen receptor (AR) and HIF1 transcription factors were identified among the differentially expressed genes by using published lists. Biological processes affected by ADT were determined by gene ontology analysis. HIF1α protein expression in xenografts and biopsy samples from 35 patients receiving neoadjuvant ADT was assessed by immunohistochemistry.

RESULTS

A total of 1344 genes showed more than 2-fold change in expression by ADT, including 35 downregulated and 5 upregulated HIF1 targets. Six genes were shared HIF1 and AR targets, and their downregulation was confirmed with quantitative RT-PCR. Significant suppression of the biological processes proliferation, metabolism, and stress response in androgen-deprived xenografts was found, consistent with tumor regression. Nineteen downregulated HIF1 targets were involved in those significant biological processes, most of them in metabolism. Four of these were shared AR and HIF1 targets, including genes encoding the regulatory glycolytic proteins HK2, PFKFB3, and SLC2A1. Most of the downregulated HIF1 targets were induced by hypoxia in androgen-responsive prostate cancer cell lines, confirming their role as hypoxia-responsive HIF1 targets in prostate cancer. Downregulation of HIF1 targets was consistent with the absence of HIF1α protein in xenografts and downregulation in patients by ADT (P<.001).

CONCLUSIONS

AR repression by ADT may lead to downregulation of HIF1 signaling independently of hypoxic fraction, and this may contribute to tumor regression. HIF1α expression is probably not a useful hypoxia biomarker during ADT in prostate cancer.