A Systematic Review of the Efficacy and Toxicity of Brachytherapy Boost Combined with External Beam Radiotherapy for Nonmetastatic Prostate Cancer

CONTEXT

The optimum use of brachytherapy (BT) combined with external beam radiotherapy (EBRT) for localised/locally advanced prostate cancer (PCa) remains uncertain.

OBJECTIVE

To perform a systematic review to determine the benefits and harms of EBRT-BT.

EVIDENCE ACQUISITION

Ovid MEDLINE, Embase, and EBM Reviews-Cochrane Central Register of Controlled Trials databases were systematically searched for studies published between January 1, 2000 and June 7, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Eligible studies compared low- or high-dose-rate EBRT-BT against EBRT ± androgen deprivation therapy (ADT) and/or radical prostatectomy (RP) ± postoperative radiotherapy (RP ± EBRT). The main outcomes were biochemical progression-free survival (bPFS), severe late genitourinary (GU)/gastrointestinal toxicity, metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS), at/beyond 5 yr. Risk of bias was assessed and confounding assessment was performed. A meta-analysis was performed for randomised controlled trials (RCTs).

EVIDENCE SYNTHESIS

Seventy-three studies were included (two RCTs, seven prospective studies, and 64 retrospective studies). Most studies included participants with intermediate-or high-risk PCa. Most studies, including both RCTs, used ADT with EBRT-BT. Generally, EBRT-BT was associated with improved bPFS compared with EBRT, but similar MFS, CSS, and OS. A meta-analysis of the two RCTs showed superior bPFS with EBRT-BT (estimated fixed-effect hazard ratio [HR] 0.54 [95% confidence interval {CI} 0.40-0.72], p < 0.001), with absolute improvements in bPFS at 5-6 yr of 4.9-16%. However, no difference was seen for MFS (HR 0.84 [95% CI 0.53-1.28], p = 0.4) or OS (HR 0.87 [95% CI 0.63-1.19], p = 0.4). Fewer studies examined RP ± EBRT. There is an increased risk of severe late GU toxicity, especially with low-dose-rate EBRT-BT, with some evidence of increased prevalence of severe GU toxicity at 5-6 yr of 6.4-7% across the two RCTs.

CONCLUSIONS

EBRT-BT can be considered for unfavourable intermediate/high-risk localised/locally advanced PCa in patients with good urinary function, although the strength of this recommendation based on the European Association of Urology guideline methodology is weak given that it is based on improvements in biochemical control.

PATIENT SUMMARY

We found good evidence that radiotherapy combined with brachytherapy keeps prostate cancer controlled for longer, but it could lead to worse urinary side effects than radiotherapy without brachytherapy, and its impact on cancer spread and patient survival is less clear.

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.

Determining Combined Modality Dosimetric Constraints by Integration of IMRT and LDR Prostate Brachytherapy Dosimetry and Correlation with Toxicity

Purpose

Intermediate- and high-risk prostate cancer patients undergoing combination external beam radiation therapy (EBRT) and low dose rate (LDR) brachytherapy have demonstrated increased genitourinary (GU) toxicity. We have previously demonstrated a method to combine EBRT and LDR dosimetry. In this work, we use this technique for a sample of patients with intermediate- and high-risk prostate cancer, correlate with clinical toxicity, and suggest preliminary summed organ-at-risk constraints for future investigation.

Methods and Materials

Intensity modulated EBRT and ¹⁰³Pd-based LDR treatment plans were combined for 138 patients using biological effective dose (BED) and deformable image registration. GU and gastrointestinal (GI) toxicity were compared with combined dosimetry for the urethra, bladder, and rectum. Differences between doses in each toxicity grade were assessed by analysis of variance (α = 0.05). Combined dosimetric constraints are proposed using the mean organ-at-risk dose, subtracting 1 standard deviation for a conservative recommendation.

Results

The majority of our 138-patient cohort experienced grade 0 to 2 GU or GI toxicity. Six grade 3 toxicities were noted. Mean prostate BED D90 (± 1 standard deviation) was 165.5±11.1 Gy. Mean urethra BED D10 was 230.3±33.9 Gy. Mean bladder BED was 35.2±11.0 Gy. Mean rectum BED D2cc was 85.6±24.3 Gy. Significant dosimetric differences between toxicity grades were found for mean bladder BED, bladder D15, and rectum D50, but differences between individual means were not statistically significant. Given the low incidence of grade 3 GU and GI toxicity, we propose urethra D10 <200 Gy, rectum D2cc <60 Gy, and bladder D15 <45 Gy as preliminary dose constraints for combined modality therapy.

Conclusions

We successfully applied our dose integration technique to a sample of patients with intermediate- and high-risk prostate cancer. Incidence of grade 3 toxicity was low, suggesting that combined doses observed in this study were safe. We suggest preliminary dose constraints as a conservative starting point to investigate and escalate prospectively in a future study.

Integrating external beam and prostate seed implant dosimetry for intermediate and high-risk prostate cancer using biologically effective dose: Impact of image registration technique

PURPOSE

Combining external beam radiation therapy (EBRT) and prostate seed implant (PSI) is efficacious in treating intermediate- and high-risk prostate cancer at the cost of increased genitourinary toxicity. Accurate combined dosimetry remains elusive due to lack of registration between treatment plans and different biological effect. The current work proposes a method to convert physical dose to biological effective dose (BED) and spatially register the dose distributions for more accurate combined dosimetry.

METHODS AND MATERIALS

A PSI phantom was CT scanned with and without seeds under rigid and deformed transformations. The resulting CTs were registered using image-based rigid registration (RI), fiducial-based rigid registration (RF), or b-spline deformable image registration (DIR) to determine which was most accurate. Physical EBRT and PSI dose distributions from a sample of 91 previously-treated combined-modality prostate cancer patients were converted to BED and registered using RI, RF, and DIR. Forty-eight (48) previously-treated patients whose PSI occurred before EBRT were included as a "control" group due to inherent registration. Dose-volume histogram (DVH) parameters were compared for RI, RF, DIR, DICOM, and scalar addition of DVH parameters using ANOVA or independent Student's t tests (α = 0.05).

RESULTS

In the phantom study, DIR was the most accurate registration algorithm, especially in the case of deformation. In the patient study, dosimetry from RI was significantly different than the other registration algorithms, including the control group. Dosimetry from RF and DIR were not significantly different from the control group or each other.

CONCLUSIONS

Combined dosimetry with BED and image registration is feasible. Future work will utilize this method to correlate dosimetry with clinical outcomes.

Brachytherapy focal dose escalation using ultrasound based tissue characterization by patients with non-metastatic prostate cancer: Five-year results from single-center phase 2 trial

PURPOSE

This prospective trial investigates side effects and efficacy of focal dose escalation with brachytherapy for patients with prostate cancer.

METHODS AND MATERIALS

In the Phase II, monocentric prospective trial 101 patients with low-/intermediate- and high-risk prostate cancer were enrolled between 2011 and 2013. Patients received either PDR-/HDR-brachytherapy alone with 86-90 Gy (EQD2, α/β = 3 Gy) or PDR-/HDR-brachytherapy as boost after external beam radiation therapy up to a total dose of 91-96 Gy (EQD2, α/β = 3 Gy). Taking place brachytherapy all patients received the simultaneous integrated focal boost to the intra-prostatic tumor lesions visible in computer-aided ultrasonography (HistoScanning™) - up to a total dose of 108-119 Gy (EQD2, α/β = 3 Gy). The primary endpoint was toxicity. Secondary endpoints were cumulative freedom from local recurrence, PSA-free survival, distant metastases-free survival, and overall survival. This trial is registered with ClinicalTrials.gov, number NCT01409876.

RESULTS

Median follow-up was 65 months. Late toxicity was generally low with only four patients scoring urinary grade 3 toxicity (4/101, 4%). Occurrence of any grade of late rectal toxicities was very low. We did not register any grade ≥2 of late rectal toxicities. The cumulative 5 years local recurrence rate (LRR) for all patients was 1%. Five years- biochemical disease-free survival estimates according Kaplan-Meier were 98,1% and 81,3% for low-/intermediate-risk and high-risk patients, respectively. Five years metastases-free survival estimates according Kaplan-Meier were 98,0% and 83,3% for all patients, low-/intermediate-risk and high-risk patients, respectively.

CONCLUSIONS

The 5 years-results from this Phase II Trial show that focal dose escalation with computer-aided ultrasonography and brachytherapy for patients with non-metastatic prostate cancer is safe and effective.

Trends in Androgen Deprivation Use in Men with Intermediate Risk Prostate Cancer Who Underwent Radiotherapy

Purpose

Until 2018, National Cancer Comprehensive Network guidelines recommended androgen deprivation therapy (ADT) for all men with intermediate-risk prostate cancer who had undergone radiation therapy. Intermediate risk was stratified as favorable and unfavorable in 2018, and ADT recommendation was limited to men with unfavorable intermediate-risk prostate cancer. Data suggesting this stratification and treatment deintensification were first published in December 2013. This study characterizes US national trends for demographic, clinical, and socioeconomic factors associated with ADT use in men with intermediate-risk prostate cancer who have undergone definitive radiation therapy.

Methods and Materials

This retrospective cohort study examined 108,185 men in the National Cancer Database who were diagnosed with intermediate-risk prostate cancer from 2004 to 2016. Temporal trends in demographic, clinical, and socioeconomic factors among men with intermediate-risk prostate cancer and associations with the use of ADT were characterized.

Results

In total, 108,185 men diagnosed with intermediate-risk prostate cancer underwent radiation therapy from 2004 to 2016. Of these men, 41.09% received ADT. Among the 60,705 men with favorable intermediate-risk prostate cancer, 32.06% received ADT. Among the 47,480 men with unfavorable intermediate-risk prostate cancer, 52.64% received ADT. On multivariate analysis, use of ADT was associated with age and year of diagnosis; being a race other than White; having government-based insurance; having a higher prostate-specific antigen level, tumor stage, and Gleason score; receiving treatment at a nonacademic center; and receiving external beam radiation therapy alone.

Conclusions

The findings highlight that ADT use is variable in men undergoing definitive radiation therapy for intermediate-risk prostate cancer, with the data suggesting that several clinical and socioeconomic disparities influence its use. The findings suggest that a significant proportion of men with favorable intermediate-risk prostate cancer receive ADT and remain candidates for treatment de-escalation, whereas a significant proportion of men with unfavorable intermediate-risk prostate cancer may be undertreated when ADT is omitted.

125I Interstitial brachytherapy with or without androgen deprivation therapy among unfavorable-intermediate and high-risk prostate cancer

PURPOSE/OBJECTIVE(S)

To determine if patients with unfavorable intermediate-risk (UIR), high-risk (HR), or very high-risk (VHR) prostate cancer (PCa) treated with ¹²⁵I interstitial brachytherapy benefit from androgen deprivation therapy (ADT).

MATERIALS/METHODS

We reviewed our institutional database of patients with UIR, HR, or VHR PCa, per 2018 NCCN risk classification, treated with definitive ¹²⁵I interstitial brachytherapy with or without ADT from 1998-2017. Outcomes including biochemical failure (bF), distant metastases (DM), and overall survival (OS) were analyzed with the Kaplan-Meier method and Cox proportional hazards regression. PCa-specific mortality (PCSM) was analyzed with Fine-Gray competing-risk regression.

RESULTS

Of 1033 patients, 262 (25%) received ADT and 771 (75%) did not. Median ADT duration was 6 months. By risk group, 764 (74%) patients were UIR, 219 (21%) HR, and 50 (5%) VHR. ADT was more frequently given to HR (50%) and VHR (56%) patients compared to UIR (16%; p<0.001), to older patients (p<0.001), corresponding with increasing PSA (p<0.001) and Grade Group (p<0.001). Median follow-up was 4.9 years (0.3-17.6 years). On multivariable analysis accounting for risk group, age, and year of treatment, ADT was not associated with bF, DM, PCSM, or OS (p≥0.05 each).

CONCLUSION

Among patients with UIR, HR, and VHR PCa, the addition of ADT to ¹²⁵I interstitial brachytherapy was not associated with improved outcomes, and no subgroup demonstrated benefit. Our findings do not support the use of ADT in combination with ¹²⁵I interstitial brachytherapy. Prospective studies are required to elucidate the role of ADT for patients with UIR, HR, and VHR PCa treated with prostate brachytherapy.

Low dose rate brachytherapy for primary treatment of localized prostate cancer: A systemic review and executive summary of an evidence-based consensus statement

PURPOSE

The purpose of this guideline is to present evidence-based consensus recommendations for low dose rate (LDR) permanent seed brachytherapy for the primary treatment of prostate cancer.

METHODS AND MATERIALS

The American Brachytherapy Society convened a task force for addressing key questions concerning ultrasound-based LDR prostate brachytherapy for the primary treatment of prostate cancer. A comprehensive literature search was conducted to identify prospective and multi-institutional retrospective studies involving LDR brachytherapy as monotherapy or boost in combination with external beam radiation therapy with or without adjuvant androgen deprivation therapy. Outcomes included disease control, toxicity, and quality of life.

RESULTS

LDR prostate brachytherapy monotherapy is an appropriate treatment option for low risk and favorable intermediate risk disease. LDR brachytherapy boost in combination with external beam radiation therapy is appropriate for unfavorable intermediate risk and high-risk disease. Androgen deprivation therapy is recommended in unfavorable intermediate risk and high-risk disease. Acceptable radionuclides for LDR brachytherapy include iodine-125, palladium-103, and cesium-131. Although brachytherapy monotherapy is associated with increased urinary obstructive and irritative symptoms that peak within the first 3 months after treatment, the median time toward symptom resolution is approximately 1 year for iodine-125 and 6 months for palladium-103. Such symptoms can be mitigated with short-term use of alpha blockers. Combination therapy is associated with worse urinary, bowel, and sexual symptoms than monotherapy. A prostate specific antigen <= 0.2 ng/mL at 4 years after LDR brachytherapy may be considered a biochemical definition of cure.

CONCLUSIONS

LDR brachytherapy is a convenient, effective, and well-tolerated treatment for prostate cancer.

Brachytherapy boost (BT-boost) or stereotactic body radiation therapy boost (SBRT-boost) for high-risk prostate cancer (HR-PCa)

Systematic review for the treatment of high-risk prostate cancer (HR-PCa, D'Amico classification risk system) with external body radiation therapy (EBRT)+brachytherapy-boost (BT-boost) or with EBRT+stereotactic body RT-boost (SBRT-boost). In March 2020, 391 English citations on PubMed matched with search terms "high risk prostate cancer boost". Respectively 9 and 48 prospective and retrospective studies were on BT-boost and 7 retrospective studies were on SBRT-boost. Two SBRT-boost trials were prospective. Only one study (ASCENDE-RT) directly compared the gold standard treatment [dose-escalation (DE)-EBRT+androgen deprivation treatment (ADT)] versus EBRT+ADT+BT-boost. Biochemical control rates at 9 years were 83% in the experimental arm versus 63% in the standard arm. Cumulative incidence of late grade 3 urinary toxicity in the experimental arm and in the standard arm was respectively 18% and 5%. Two recent studies with HR-PCa (National Cancer Database) demonstrated better overall survival with BT-boost (low dose rate LDR or high dose rate HDR) compared with DE-EBRT. These recent findings demonstrate the superiority of EBRT+BT-boost+ADT versus DE-EBRT+ADT for HR-PCa. It seems that EBRT+BT-boost+ADT could now be considered as a gold standard treatment for HR-PCa. HDR or LDR are options. SBRT-boost represents an attractive alternative, but the absence of randomised trials does not allow us to conclude for HR-PCa. Prospective randomised international phase III trials or meta-analyses could improve the level of evidence of SBRT-boost for HR-PCa.

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.

A comparison of outcomes for patients with intermediate and high risk prostate cancer treated with low dose rate and high dose rate brachytherapy in combination with external beam radiotherapy

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Superior biochemical progression free survival for LDR in combination with EBRT.

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On multivariable analysis, HDR and EBRT and Gleason ≥8 predicted for progression.

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Low cumulative incidence of ≥grade 3 GU and GI toxicities.

Introduction

There is evidence to support use of external beam radiotherapy (EBRT) in combination with both low dose rate brachytherapy (LDR–EBRT) and high dose rate brachytherapy (HDR–EBRT) to treat intermediate and high risk prostate cancer.

Methods

Men with intermediate and high risk prostate cancer treated using LDR–EBRT (treated between 1996 and 2007) and HDR–EBRT (treated between 2007 and 2012) were identified from an institutional database. Multivariable analysis was performed to evaluate the relationship between patient, disease and treatment factors with biochemical progression free survival (bPFS).

Results

116 men were treated with LDR-EBRT and 171 were treated with HDR–EBRT. At 5 years, bPFS was estimated to be 90.5% for the LDR–EBRT cohort and 77.6% for the HDR–EBRT cohort. On multivariable analysis, patients treated with HDR–EBRT were more than twice as likely to experience biochemical progression compared with LDR–EBRT (HR 2.33, 95% CI 1.12–4.07). Patients with Gleason ≥8 disease were more than five times more likely to experience biochemical progression compared with Gleason 6 disease (HR 5.47, 95% CI 1.26–23.64). Cumulative incidence of ≥grade 3 genitourinary and gastrointestinal toxicities for the LDR–EBRT and HDR–EBRT cohorts were 8% versus 4% and 5% versus 1% respectively, although these differences did not reach statistical significance.

Conclusion

LDR–EBRT may provide more effective PSA control at 5 years compared with HDR–EBRT. Direct comparison of these treatments through randomised trials are recommended to investigate this hypothesis further.

Gleason pattern 5 is associated with an increased risk for metastasis following androgen deprivation therapy and radiation: An analysis of RTOG 9202 and 9902

BACKGROUND/PURPOSE

Stratification of Gleason score (GS) into three categories (2-6, 7, and 8-10) may not fully utilize its prognostic discrimination, with Gleason pattern 5 (GP5) previously identified as an independent adverse factor.

MATERIALS/METHODS

Patients treated on RTOG 9202 (n = 1292) or RTOG 9902 (n = 378) were pooled and assessed for association of GS and GP5 on biochemical failure (BF), local failure (LF), distant metastasis (DM), and overall survival (OS). Fine and Gray's regression and cumulative incidence methods were used for univariate and multivariate analyses.

RESULTS

With median follow-up of 9.4 years, patients with GS 8-10 with GP5 had worse outcome than GS 4 + 4 for DM on both RTOG9202 (p = 0.038) and RTOG9902 (p < 0.001) with a trend toward worse OS (p = 0.059 and p = 0.089, respectively), but without differences in BF or LF. At 10-years DM was higher by 11% (RTOG 9202) and 18% (RTOG 9902) with GP5 compared to GS 4 + 4. On multivariate analysis restricted to long-term androgen deprivation therapy the presence of GP5 substantially increased distant metastasis (HR = 0.43, 95%CI: 0.24-0.76, p = 0.0039) with a trend toward worse OS (HR:0.74, 95% CI:0.54-1.0, p = 0.052) without association with LF (HR:0.55, 95%CI:0.28-1.09, p = 0.085) or BF (HR:1.15, 95%CI:0.84-1.59, p = 0.39). We did not observed substantial differences between Gleason 3 + 5, 5 + 3, or Gleason 9-10.

CONCLUSIONS

These results validate GP5 as an independent prognostic factor which is strongest for DM. As a result GP5 should be considered when stratifying patients with GS 8 and may be a patient population in which to evaluate newly approved systemic therapies or additional local treatments.

Application of a Prognostic Stratification System for High-risk Prostate Cancer to Patients Treated With Radiotherapy: Implications for Treatment Optimization

OBJECTIVES

We applied an established prognostic model to high-risk prostate cancer (HRPC) patients treated with radiotherapy (RT) and evaluated the influence of clinical and treatment variables on treatment outcomes.

METHODS

In total, 1075 HRPC patients undergoing definitive radiotherapy (RT) between 1995 and 2010 were retrospectively reviewed. Median follow-up was 62.3 months. Patients received either dose-escalated external beam radiotherapy (n=628, EBRT) or combined-modality radiotherapy (n=447, pelvic RT and low-dose rate brachytherapy boost, CMRT). 82.9% received androgen-deprivation therapy (ADT). A prognostic model stratified patients into predefined groups (good, intermediate, and poor). Kaplan-Meier methods and Cox proportional hazards regressions assessed biochemical failure (BF), distant metastasis (DM), prostate cancer-specific mortality (PCSM) and overall mortality (OM). C-indices analyzed predictive value.

RESULTS

The model was prognostic; C-indices for BF, DM, PCSM and OM were: 0.62, 0.64, 0.61, and 0.57. On multivariate analysis, CMRT and longer ADT (≥24 mo) were associated with improved BF, DM, and PCSM. Gleason score (GS) 9-10 was the strongest predictor of PCSM. C-indices for BF, DM, PCSM, and OM using a 4-compartment model incorporating GS 9-10 were: 0.62, 0.65, 0.68, and 0.56. In poor-prognosis patients (GS 8-10+additional risk factors), CMRT+LTADT (>12 mo) had 10-year PCSM (3.7%±3.6%), comparing favorably to 25.8%±9.2% with EBRT+LTADT.

CONCLUSIONS

The model applies to high-risk RT patients; GS 9-10 remains a powerful predictor of PCSM. Comparing similar prognosis patients, CMRT is associated with improved disease-specific outcomes relative to EBRT. In poor-prognosis patients, CMRT+LTADT yields superior 10-year PCSM, potentially improving RT treatment personalization for those with HRPC.

High-dose-rate brachytherapy monotherapy versus low-dose-rate brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer

BACKGROUND

To compare the outcome of high-dose-rate interstitial brachytherapy (HDR-BT) monotherapy and low-dose-rate brachytherapy (LDR-BT) with or without external beam radiotherapy (EBRT) for localized prostate cancer.

METHODS AND MATERIALS

We compared 352 patients treated with HDR-BT as monotherapy (median follow-up time 84 months, NCCN risk classification; low: intermediate: high = 28:145:179) and 486 patients with LDR-BT with or without EBRT (90 months, 194:254:38). HDR-BT treated advanced disease with more hormonal therapy than LDR-BT. LDR-BT excluded patients with T3b-T4 tumor and initial PSA >50 ng/ml. Inverse probability of treatment weighting (IPTW) involving propensity scores was used to reduce background selection bias.

RESULTS

The actuarial 5-year biochemical failure-free survival rates (bNED) were 92.9% and 95.6% (p = 0.25) in the HDR-BT and LDR-BT groups, respectively, and it was 100% and 97.3% (p = 0.99) in the low-risk, 95.6% and 94.3% (p = 0.19) in the intermediate, 89.6% and 94.9% (p = 0.26) in the high-risk groups, and 93.1% and 94.9% (p = 0.98) in selected high-risk group excluding T3b-4 and initial PSA ≥50. IPTW correction also indicated no difference in bNED between LDR-BT and HDR-BT groups. LDR-BT showed a higher incidence of genitourinary (GU) toxicity grade ≥2 than that of HDR-BT in the acute phase and grade 1 toxicity in late phase. Acute GU toxicity grade ≥1 predicted late GU toxicity grade ≥2. External beam radiotherapy plus LDR-BT elevated GI toxicity than LDR-BT only group. Accumulated incidence of late grade ≥2 GU and GU toxicity was equivalent between HDR-BT and LDR-BT. No grade 4 or 5 toxicities were detected in either modality.

CONCLUSION

HDR-BT monotherapy showed an equivalent outcome to that of LDR-BT with or without EBRT for low-, intermediate- and selected high-risk patients. LDR-BT showed equivalent incidence of grade ≥2 late GI and GU toxicities and higher grade ≥2 acute GU toxicity as that of HDR-BT as a monotherapy.

Five-year effectiveness of low-dose-rate brachytherapy: comparisons with nomogram predictions in patients with non-metastatic prostate cancer presenting significant control of intra- and periprostatic disease

PURPOSE

To assess the effectiveness of low-dose-rate (LDR) brachytherapy in patients with localized prostate cancer and to compare the outcome with predictions from Kattan and Partin nomograms at 60 months after seed implantation.

MATERIAL AND METHODS

One thousand, one hundred and eighty-seven patients with localized prostate cancer at low-, intermediate-, or high-risk of progression received LDR brachytherapy using iodine-125 seeds with curative intent, applied as monotherapy or in combination with external beam radiation therapy (EBRT), and/or androgen deprivation therapy (ADT). At 60 months after seed implantation, data of 1,064 patients (1,058 alive + 6 who died of prostate cancer) were analyzed for biochemical progression-free survival (bPFS) based on prostate-specific antigen (PSA) levels using the Phoenix definition. Five-year bPFS probabilities were determined for various risk group classifications (d'Amico, Mt. Sinai, MSKCC/Seattle, NCCN). Outcomes were also compared to patient-individualized nomogram predictions of 5-year bPFS (Kattan 2002) and probability of organ-confined disease (Kattan 2002, Partin 2007).

RESULTS

Overall, 93.3% (993/1,064) of the patients were free of biochemical progression within 5 years, while the average 5-year bPFS probability according to the Kattan nomogram was significantly lower (85%, p < 0.001). Outcomes were significantly better than Kattan nomogram predictions in the subgroup of patients with monotherapy as well as in patients additionally treated with EBRT. Comparison of the overall outcome with nomogram predictions for organ-confined disease (Kattan nomogram: 50%; Partin nomogram: 65%) revealed a significant probability of LDR brachytherapy to destroy periprostatic tumor spread (p < 0.001) in all risk group constellations, even in high-risk patients.

CONCLUSIONS

The results indicate high effectiveness of LDR brachytherapy in all risk groups, significantly better than predicted with the Kattan nomogram in most subgroups. The significant superiority of LDR brachytherapy compared to nomogram predictions of organ-confined disease suggests that LDR brachytherapy effectively controls both intra- and periprostatic disease.

Prostate cancer-specific death in brachytherapy treated high-risk patients stratified by pre-treatment PSA

Purpose

To evaluate prostate-cancer specific mortality (PCSM) in a cohort of high-risk patients treated with a permanent prostate brachytherapy approach, stratified by pre-treatment PSA.

Material and methods

448 high-risk patients (NCCN criteria) underwent permanent prostate brachytherapy. High risk patients were stratified by pre-treatment PSA (≤ 10.0, 10.1-20, and > 20 ng/ml). Biochemical failure (BF), prostate cancer-specific mortality (PCSM), distant failure (DM), and overall mortality (OM) were assessed as a function of prognostic group. Multiple clinical, treatment, and dosimetric parameters were evaluated for impact on outcome.

Results

The 10-year OM, BF, and PCSM for the entire cohort were 28.5%, 13.3%, and 4.9%, respectively. At 10 years, PCSM was 2.5%, 10.7%, and 4.5% in the PSA ≤ 10, 10.1-20, and > 20 ng/ml groups, respectively. No statistically significant differences in BF or overall survival (OS) were noted when stratified by pre-treatment PSA. DF was the most common in the 10.1-20 ng/ml cohort (8.6% at 10 years). In multivariate analysis, PCSM was most closely related to percent positive biopsies (p = 0.001) and tobacco (p = 0.042).

Conclusions

High-risk prostate cancer treated with permanent prostate brachytherapy and supplemental external beam radiotherapy resulted in excellent long-term biochemical control and PCSM. Overall, PCSM was low in all cohorts but highest in the intermediate PSA group (10.1-20 ng/ml).

Intensity-Modulated Radiation Therapy with Stereotactic Body Radiation Therapy Boost for Unfavorable Prostate Cancer: A Report on 3-Year Toxicity

Background

Recent data suggest that intensity-modulated radiation therapy (IMRT) plus brachytherapy boost for unfavorable prostate cancer provides improved biochemical relapse-free survival over IMRT alone. Stereotactic body radiation therapy (SBRT) may be a less invasive alternative to brachytherapy boost. Here, we report the 3-year gastrointestinal (GI) and genitourinary (GU) toxicities of IMRT plus SBRT boost.

Materials and methods

Between March 2008 and September 2012, patients with prostate cancer were treated with robotic SBRT (19.5 Gy in three fractions) followed by fiducial-guided IMRT (45–50.4 Gy) on an institutional protocol. Toxicity was prospectively graded using the common terminology criteria for adverse events version 4.0 (CTCAEv.4) at the start of and at 1- to 6-month intervals after therapy. Rectal telangiectasias were graded using the Vienna Rectoscopy Score (VRS).

Results

At a median follow-up of 4.2 years (2.4–7.5), 108 patients (4 low-, 45 intermediate-, and 59 high-risk) with a median age of 74 years (55–92) were treated with SBRT plus IMRT, with 8% on anticoagulation and an additional 48% on antiplatelet therapy at the start of therapy. The cumulative incidence of late ≥grade 2 GI toxicity was 12%. Of these, 7% were due to late rectal bleeding, with six patients requiring up to two coagulation procedures. One patient with rectal telangiectasias was treated with hyperbaric oxygen (grade 3 toxicity). No rectal fistulas or stenoses were observed. Ten patients had multiple non-confluent telangiectasias (VRS grade 2), and three patients had multiple confluent telangiectasias (VRS grade 3). The cumulative incidence of late grade 3 GU toxicity was 6%. Most late toxicities were due to hematuria requiring bladder fulguration. There were no late ≥grade 4 GU toxicities.

Conclusion

Rates of clinically significant GI and GU toxicities are modest following IMRT plus SBRT boost. Future studies should compare cancer control, quality of life, and toxicity with other treatment modalities for patients with high-risk prostate cancer.

American Brachytherapy Society Task Group Report: Use of androgen deprivation therapy with prostate brachytherapy-A systematic literature review

PURPOSE

Prostate brachytherapy (PB) has well-documented excellent long-term outcomes in all risk groups. There are significant uncertainties regarding the role of androgen deprivation therapy (ADT) with brachytherapy. The purpose of this report was to review systemically the published literature and summarize present knowledge regarding the impact of ADT on biochemical progression-free survival (bPFS), cause-specific survival (CSS), and overall survival (OS).

METHODS AND MATERIALS

A literature search was conducted in Medline and Embase covering the years 1996-2016. Selected were articles with >100 patients, minimum followup 3 years, defined risk stratification, and directly examining the role and impact of ADT on bPFS, CSS, and OS. The studies were grouped to reflect disease risk stratification. We also reviewed the impact of ADT on OS, cardiovascular morbidity, mortality, and on-going brachytherapy randomized controlled trials (RCTs).

RESULTS

Fifty-two selected studies (43,303 patients) were included in this review; 7 high-dose rate and 45 low-dose rate; 25 studies were multi-institutional and 27 single institution (retrospective review or prospective data collection) and 2 were RCTs. The studies were heterogeneous in patient population, risk categories, risk factors, followup time, and treatment administered, including ADT administration and duration (median, 3-12 months);71% of the studies reported a lack of benefit, whereas 28% showed improvement in bPFS with addition of ADT to PB. The lack of benefit was seen in low-risk and favorable intermediate-risk (IR) disease and most high-dose rate studies. A bPFS benefit of up to 15% was seen with ADT use in patients with suboptimal dosimetry, those with multiple adverse risk factors (unfavorable IR [uIR]), and most high-risk (HR) studies. Four studies reported very small benefit to CSS (2%). None of the studies showed OS advantage; however, three studies reported an absolute 5-20% OS detriment with ADT. Literature suggests that OS detriment is more likely in older patients or those with pre-existing cardiovascular disease. Four RCTs with an adequate number of patients and well-defined risk stratification are in progress. One RCT will answer the question regarding the role of ADT with PB in favorable IR patients and the other three RCTs will focus on optimal duration of ADT in the uIR and favorable HR population.

CONCLUSIONS

Patients treated with brachytherapy have excellent long-term disease outcomes. Existing evidence shows no benefit of adding ADT to PB in low-risk and favorable IR patients. UIR and HR patients and those with suboptimal dosimetry may have up to 15% improvement in bPFS with addition of 3-12 months of ADT, with uncertain impact on CSS and a potential detriment on OS. To minimize morbidity, one should exercise caution in prescribing ADT together with PB, in particular to older men and those with existing cardiovascular disease. Due to the retrospective nature of this evidence, significant selection, and treatment bias, no definitive conclusions are possible. RCT is urgently needed to define the potential role and optimal duration of ADT in uIR and favorable HR disease.

Magnetic resonance imaging-guided functional anatomy approach to prostate brachytherapy

PURPOSE

To provide an MRI based functional anatomy guide to prostate brachytherapy.

METHODS AND MATERIALS

We performed a narrative review of periprostatic functional anatomy and the significance of this anatomy in prostate brachytherapy treatment planning.

RESULTS

MRI has improved delineation of gross tumor and critical periprostatic structures that have been implicated in toxicity. Furthermore, MRI has revealed the significant anatomic variants and the dynamic nature of these structures that can have significant implications for treatment planning and dosimetry.

CONCLUSIONS

The MRI-based functional anatomy approach to prostate brachytherapy takes into account extent of disease, its relation to the patient's individual anatomy, and functional baseline to optimize the therapeutic ratio of prostate cancer treatment.

ACR appropriateness criteria: Permanent source brachytherapy for prostate cancer

PURPOSE

To provide updated American College of Radiology (ACR) appropriateness criteria for transrectal ultrasound-guided transperineal interstitial permanent source brachytherapy.

METHODS AND MATERIALS

The ACR appropriateness criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

RESULTS

Permanent prostate brachytherapy (PPB) is a treatment option for appropriately selected patients with localized prostate cancer with low to very high risk disease. PPB monotherapy remains an appropriate and effective curative treatment for low-risk prostate cancer patients demonstrating excellent long-term cancer control and acceptable morbidity. PPB monotherapy can be considered for select intermediate-risk patients with multiparametric MRI useful in evaluation of such patients. High-risk patients treated with PPB should receive supplemental external beam radiotherapy (EBRT) along with androgen deprivation. Similarly, patients with involved pelvic lymph nodes may also be considered for such combined treatment but reported long-term outcomes are limited. Computed tomography-based postimplant dosimetry completed within 60 days of PPB is essential for quality assurance. PPB may be considered for treatment of local recurrence after EBRT but is associated with an increased risk of toxicity.

CONCLUSIONS

Updated appropriateness criteria for patient evaluation, selection, treatment, and postimplant dosimetry are given. These criteria are intended to be advisory only with the final responsibility for patient care residing with the treating clinicians.

American Brachytherapy Society Task Group Report: Combination of brachytherapy and external beam radiation for high-risk prostate cancer

PURPOSE

To review outcomes for high-risk prostate cancer treated with combined modality radiation therapy (CMRT) utilizing external beam radiation therapy (EBRT) with a brachytherapy boost.

METHODS AND MATERIALS

The available literature for high-risk prostate cancer treated with combined modality radiation therapy was reviewed and summarized.

RESULTS

At this time, the literature suggests that the majority of high-risk cancers are curable with multimodal treatment. Several large retrospective studies and three prospective randomized trials comparing CMRT to dose-escalated EBRT have demonstrated superior biochemical control with CMRT. Longer followup of the randomized trials will be required to determine if this will translate to a benefit in metastasis-free survival, disease-specific survival, and overall survival. Although greater toxicity has been associated with CMRT compared to EBRT, recent studies suggest that technological advances that allow better definition and sparing of critical adjacent structures as well as increasing experience with brachytherapy have improved implant quality and the toxicity profile of brachytherapy. The role of androgen deprivation therapy is well established in the external beam literature for high-risk disease, but there is controversy regarding the applicability of these data in the setting of dose escalation. At this time, there is not sufficient evidence for the omission of androgen deprivation therapy with dose escalation in this population. Comparisons with surgery remain limited by differences in patient selection, but the evidence would suggest better disease control with CMRT compared to surgery alone.

CONCLUSIONS

Due to a series of technological advances, modern combination series have demonstrated unparalleled rates of disease control in the high-risk population. Given the evidence from recent randomized trials, combination therapy may become the standard of care for high-risk cancers.

The need for more aggressive therapy for men with Gleason 9-10 disease compared to Gleason ≤8 high-risk prostate cancer

PURPOSE

To evaluate the outcomes of prostate cancer patients with high-risk disease stratified by Gleason Score (GS) (GS ≤8 vs GS ≥9) treated with external beam radiotherapy (EBRT).

METHODS

The medical records of patients who underwent EBRT between 2003 and 2011 and had nonmetastatic high-risk disease were analyzed retrospectively. Patients were treated with EBRT and all patients received a dose ≥7,560 cGy. Androgen deprivation therapy was given in most patients (90%).

RESULTS

A total of 155 patients were identified (GS ≤8 n = 104, GS ≥9 n = 51), and they had a median presenting prostate-specific antigen (PSA) of 14.7 ng/mL. At a median follow-up of 69 months, the 7-year biochemical failure-free survival was 59.1% in those with GS ≥9 and 69.2% in those with GS ≤8 (p = 0.12). On MVA, Gleason 9-10 (HR 1.83, p = 0.08) was not associated with an increased risk of biochemical recurrence, while a PSA &gt;20 ng/mL (HR 2.39, p = 0.04) was associated with an increased likelihood of biochemical recurrence. Patients with GS ≥9 were noted to have worse 7-year distant metastatic-free survival (79.6% vs 90.5% p = 0.02) and cancer-specific survival (88.5% vs 97.9%, p = 0.006). On MVA, GS ≥9 was a significant indicator of distant metastatic failure and cancer-related death. Seven-year overall survival rates remained similar between the groups.

CONCLUSIONS

In this high-risk cohort, patients with GS 9-10 had significantly worse prostate cancer-related outcomes than other high-risk patients, suggesting that this group may warrant more aggressive treatment modalities than their high-risk counterparts.

Significant association of brachytherapy boost with reduced prostate cancer-specific mortality in contemporary patients with localized, unfavorable-risk prostate cancer

PURPOSE

A randomized trial recently found that adding brachytherapy (BT) boost to external beam radiation therapy (EBRT) improves biochemical recurrence-free survival but not prostate cancer-specific mortality (PCSM). We investigated the relationship between BT boost and PCSM in a modern cohort from a large population-based database.

METHODS AND MATERIALS

We conducted an analysis of patients in Surveillance, Epidemiology, and End Results diagnosed with intermediate- or high-risk prostate cancer in 2004-2011, treated with EBRT only or EBRT + BT. The cumulative incidence of PCSM was evaluated in the presence of other-cause mortality as a competing risk. Propensity score matching and multivariable Fine and Gray proportional hazard models were used to evaluate the association of combined modality RT on PCSM.

RESULTS

A total of 52,535 patients were identified, of which 19.6% were treated with EBRT + BT. One-third of cases were high-risk. On multivariable analysis, the adjusted hazard ratio (AHR) of PCSM for EBRT + BT vs. EBRT alone was 0.69 (95% confidence interval [CI], 0.55-0.87, p = 0.002), and the adjusted incidence of PCSM was 1.8% vs. 2.7% at 8 years, respectively. In subgroup analyses, the AHR for PCSM was also significantly reduced with EBRT + BT for high-risk disease (AHR 0.70; 95% CI, 0.52-0.94, p = 0.02; adjusted incidence of PCSM at 8 years, 5.4% vs. 7.6%), but not for intermediate-risk disease.

CONCLUSIONS

BT boost was associated with a moderate reduction to PCSM in men with localized unfavorable-risk prostate cancer. Those most likely to benefit are younger patients with high-risk disease.

Is supplemental external beam radiation therapy necessary for patients with higher risk prostate cancer treated with 103Pd? Results of two prospective randomized trials

PURPOSE

To determine the necessity and/or dose of supplemental external beam radiotherapy (EBRT) in conjunction with palladium-103 ((103)Pd) brachytherapy for high-risk prostate cancer patients.

METHODS AND MATERIALS

Trial 44/20 randomized patients to 44 Gy plus 90 Gy (103)Pd vs. 20 Gy with 115 Gy (103)Pd, and the subsequent trial randomized patients to the 20 Gy arm vs. 125 Gy (103)Pd without EBRT (20/0 trial). Eligibility criteria included clinically organ-confined disease with Gleason scores 7-9 and/or a pretreatment prostate-specific antigen (PSA) 10-20 ng/mL. The brachytherapy prescription dose was prescribed to the prostate gland with generous periprostatic margins. Biochemical failure (BF) was defined as a PSA >0.40 ng/mL after nadir. Median Day 0 minimum dose covering 90% of the prostate volume (D90) was >121.0% of the prescription dose. Multiple parameters were evaluated for effect on outcomes.

RESULTS

In 44/20 trial, 13-year BF, prostate cancer-specific mortality (PCSM), and overall mortality (OM) were 8.2%, 4.0%, and 42.8% vs. 8.0%, 1.0%. and 40.3% for the 44 and 20 Gy arms. In 20/0 trial, 8-year BF, PCSM, and OM were 2.1%, 0%, and 14.4% vs. 3.6%, 0%, and 16.1% in the 20 vs. 0 Gy arms. When stratified by either pretreatment PSA or by Gleason score, supplemental EBRT dose did not impact BF, PCSM, or OM. In multivariate analysis, BF was most closely related to percent positive biopsies and prostate volume. In both trials, patients with biochemically controlled disease had a median PSA of <0.02 ng/mL.

CONCLUSIONS

With high-quality brachytherapy dose distributions, supplemental EBRT did not influence BF or PCSM for patients with intermediate-risk disease. The number of patients with Gleason score 8-9 was too small to determine the role of supplemental EBRT in that cohort.

Permanent prostate brachytherapy and short-term androgen deprivation for intermediate-risk prostate cancer in Japanese men: outcome and toxicity

OBJECTIVES

To evaluate the interim outcomes of low-dose-rate permanent brachytherapy (PB) combined with short-term androgen deprivation therapy (ADT) in Japanese men with intermediate-risk prostate cancer excluding those with a Gleason score of 4+3.

METHODS

The Protocol-intermediate-risk group (Protocol-IRG) was defined as clinical stage T1c-T2c, Gleason score of 3+4, or lower and prostatic-specific antigen (PSA) level lower than 20 ng/mL. A total of 308 patients underwent brachytherapy in the protocol-IRG group (n=152) or in the low-risk group (n=156). Patients in Protocol-IRG had received at least 6 months of ADT before and after PB. Supplemental external beam radiotherapy was not used. Planned followup by PSA was carried out every 3 months for the first 2 years and every 6 months thereafter. The PSA failure was defined as nadir+2 ng/mL. Patients' Expanded Prostate Cancer Index Composite was recorded before and 3 years after treatment.

RESULTS

The median followup was 68 and 68 months for the protocol-IRG and the low-risk groups, respectively. The 5-year biological disease-free survival rates in the low-risk and protocol-IRG groups were 94.8 and 94.6%, respectively. As far as survival rates were concerned, there were no significant differences between the two groups. Overall satisfaction and sexual function at 3 years after PB had significantly improved compared with pretreatment (p=0.01 and p=0.01, respectively).

CONCLUSIONS

In intermediate-risk prostate patients, excluding those with a biopsy Gleason score of 4+3, brachytherapy with short-term ADT can be an effective treatment option for Japanese men.

Time to failure after definitive therapy for prostate cancer: implications for importance of aggressive local treatment

Purpose

To explore patterns of time to failure in men receiving high doses of permanent seed brachytherapy with or without external beam radiation therapy as a function of risk status.

Material and methods

Two thousand two hundred and thirty four patients were treated with prostate brachytherapy with median follow up of 8.0 years. The population was 35% low risk, 49% intermediate risk, and 16% high risk (NCCN). Median day 0 implant D₉₀ was 119% and V₁₀₀ was 98%. Treatment failure was defined as PSA > 0.40 ng/mL after nadir. Rates of biochemical failure, distant metastases, and prostate cancer death were determined with non-prostate death as a competing risk.

Results

For all patients, the 10-year biochemical failure, distant metastases, and cause-specific mortality were 4.4%, 1.4%, and 1.3%, respectively. The biochemical failure rates were 1.3%, 4.8%, and 10.0% for men with low, intermediate, and high risk disease, respectively. Median time to failure was 2.8 years. In men who died from prostate cancer, the median time from treatment failure to death was 4.2 years. Overall, 83% of biochemical failures and 97% of metastases occurred within the first 4 years after treatment.

Conclusions

With the dose escalation achieved by high quality brachytherapy dosimetry, even high-risk prostate cancer patients have excellent long term biochemical outcomes. Treatment failures occur early, and one third become metastatic and progress rapidly to prostate cancer death. The low frequency and pattern of failures suggest the presence of micrometastatic disease prior to treatment is rare, even in high risk patients.

β1 integrins mediate resistance to ionizing radiation in vivo by inhibiting c-Jun amino terminal kinase 1

This study was carried out to dissect the mechanism by which β1 integrins promote resistance to radiation. For this purpose, we conditionally ablated β1 integrins in the prostatic epithelium of transgenic adenocarcinoma of mouse prostate (TRAMP) mice. The ability of β1 to promote resistance to radiation was also analyzed by using an inhibitory antibody to β1 , AIIB2, in a xenograft model. The role of β1 integrins and of a β1 downstream target, c-Jun amino-terminal kinase 1 (JNK1), in regulating radiation-induced apoptosis in vivo and in vitro was studied. We show that β1 integrins promote prostate cancer (PrCa) progression and resistance to radiation in vivo. Mechanistically, β1 integrins are shown here to suppress activation of JNK1 and, consequently apoptosis, in response to irradiation. Downregulation of JNK1 is necessary to preserve the effect of β1 on resistance to radiation in vitro and in vivo. Finally, given the established crosstalk between β1 integrins and type1 insulin-like growth factor receptor (IGF-IR), we analyzed the ability of IGF-IR to modulate β1 integrin levels. We report that IGF-IR regulates the expression of β1 integrins, which in turn confer resistance to radiation in PrCa cells. In conclusion, this study demonstrates that β1 integrins mediate resistance to ionizing radiation through inhibition of JNK1 activation.

Brachytherapy in Men with Prostate Cancer: Update on Indications and Outcomes

Brachytherapy (BT), using either a low-dose-rate (LDR) or mostly high-dose-rate (HDR) technique, is the device able to deliver the highest dose-rate in the most conformal way It is used as monotherapy or in combination with external beam radiotherapy (EBRT). LDR-BT is mostly used as monotherapy; HDR-BT is combined with EBRT +/– adjuvant hormone therapy In patients with low-risk disease and in selected intermediate-risk patients, LDR-BT ensures long-term good disease control rates and HDR-BT shows similar results, even if with shorter follow-up. In patients with intermediate/high risk disease the combination therapy (EBRT + HDR-BT) provides better oncological outcomes compared to EBRT monotherapy, even if the role of adjuvant hormone therapy is still unclear. Literature shows variable efficacy of BT in case of local recurrence after EBRT and radical prostatectomy even if few cases have been reported with short follow-up. Side effects are acceptable (urogenital toxicity, urinary incontinence, sexual function) and comparable with the other treatment modalities. So far, randomized controlled trials comparing the different treatment modalities are necessary to clarify indications and real efficacy.