Long-term outcomes for patients with prostate cancer having intermediate and high-risk disease, treated with combination external beam irradiation and brachytherapy

Stereotactic Radiation Therapy versus Brachytherapy: Relative Strengths of Two Highly Efficient Options for the Treatment of Localized Prostate Cancer

Stereotactic body radiation therapy (SBRT) has become a valid option for the treatment of low- and intermediate-risk prostate cancer. In randomized trials, it was found not inferior to conventionally fractionated external beam radiation therapy (EBRT). It also compares favorably to brachytherapy (BT) even if level 1 evidence is lacking. However, BT remains a strong competitor, especially for young patients, as series with 10-15 years of median follow-up have proven its efficacy over time. SBRT will thus have to confirm its effectiveness over the long-term as well. SBRT has the advantage over BT of less acute urinary toxicity and, more hypothetically, less sexual impairment. Data are limited regarding SBRT for high-risk disease while BT, as a boost after EBRT, has demonstrated superiority against EBRT alone in randomized trials. However, patients should be informed of significant urinary toxicity. SBRT is under investigation in strategies of treatment intensification such as combination of EBRT plus SBRT boost or focal dose escalation to the tumor site within the prostate. Our goal was to examine respective levels of evidence of SBRT and BT for the treatment of localized prostate cancer in terms of oncologic outcomes, toxicity and quality of life, and to discuss strategies of treatment intensification.

PSA nadir predicts biochemical recurrence after external beam radiation therapy combined to high dose rate brachytherapy in the treatment of prostate cancer

INTRODUCTION

Prostate cancer (PCa) is the second most prevalent neoplasm among men in the world. Its treatment has a wide spectrum of alternatives and variables, ranging from active surveillance through radio and/or brachytherapy, to surgery.

OBJECTIVE

The present work aimed to identify the predictive factors for biochemical recurrence and to evaluate the toxicity of the treatment using the association of external beam radiation therapy (EBRT) with high dose rate brachytherapy (HDR-BT) applied in the treatment of patients with prostate cancer.

METHODS

Longitudinal retrospective study, using a prospectively collected database between 2005 and 2014 of 186 consecutive patients records with a diagnosis of low, intermediate, or high-risk prostate cancer treated with EBRT combined with HDR-BT, in a single medical institution located in the city of Campinas, SP, Brazil (Radium Institute). PSA increase over 2 ng/ml above the nadir PSA was considered as biochemical recurrence, following the definition of the Phoenix Consensus. Continuous and clinically relevant categorical variables (age, initial PSA, delivered dose in EBRT, number of implants, number of positive cores in transrectal biopsy, use of hormone blockade, Gleason score, TNM staging, post treatment PSA and PSA Nadir) were evaluated with absolute (n) and percentage (%) values using multiple logistic regression and validated our previously described optimal PSA nadir as predictor of biochemical recurrence.

RESULTS

Post treatment PSA was the only independent predictor of biochemical recurrence, P<0.0001. The lower the PSA nadir the lower the biochemical recurrence risk (P=0.0009). PSA nadir >1 was the best cutoff (P=0.018) determinant of biochemical recurrence. The incidence of grade 3 late toxicity to the genitourinary tract was 0.6%, and there were no cases of severe complications to the gastrointestinal tract.

CONCLUSION

External Beam Radiation Therapy conjugated to Brachytherapy in the treatment of Prostate Cancer has demonstrated low biochemical recurrence rates, mainly when PSA nadir <1, with low toxicity into both GU and GI tracts.

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.

Magnetic resonance imaging (MRI)-based radiomics for prostate cancer radiotherapy

In radiotherapy (RT) of prostate cancer, dose escalation has been shown to reduce biochemical failure. Dose escalation only to determinate prostate tumor habitats has the potential to improve tumor control with less toxicity than when the entire prostate is dose escalated. Other issues in the treatment of the RT patient include the choice of the RT technique (hypo- or standard fractionation) and the use and length of concurrent/adjuvant androgen deprivation therapy (ADT). Up to 50% of high-risk men demonstrate biochemical failure suggesting that additional strategies for defining and treating patients based on improved risk stratification are required. The use of multiparametric MRI (mpMRI) is rapidly gaining momentum in the management of prostate cancer because of its improved diagnostic potential and its ability to combine functional and anatomical information. Currently, the Prostate Imaging, Reporting and Diagnosis System (PIRADS) is the standard of care for region of interest (ROI) identification and risk classification. However, PIRADS was not designed for 3D tumor volume delineation; there is a large degree of subjectivity and PIRADS does not accurately and reproducibly elucidate inter- and intra-lesional spatial heterogeneity. "Radiomics", as it refers to the extraction and analysis of large number of advanced quantitative radiological features from medical images using high throughput methods, is perfectly suited as an engine to effectively sift through the multiple series of prostate mpMRI sequences and quantify regions of interest. The radiomic efforts can be summarized in two main areas: (I) detection/segmentation of the suspicious lesion; and (II) assessment of the aggressiveness of prostate cancer. As related to RT, the goal of the latter is in particular to identify patients at high risk for metastatic disease; and the aim of the former is to identify and segment cancerous lesions and thus provide targets for radiation boost. The article is structured as follows: first, we describe the radiomic approach; and second, we discuss the radiomic pipeline as tailored for RT of prostate cancer. In this process we summarize the current efforts and progress in integrating mpMRI radiomics into the radiotherapeutic management of prostate cancer with emphasis placed on its role in treatment target definition, treatment plan strategizing, and prognostic assessment. The described concepts, methods and tools are not currently applicable to the radiation oncology practice outside of the research setting. More data are required in the form of clinical trials to assess the robustness of radiomics-based predictive models, and to maximize the efficacy of these models.

Oncological impact of neoadjuvant hormonal therapy on permanent iodine-125 seed brachytherapy in patients with low- and intermediate-risk prostate cancer

OBJECTIVES

To determine whether neoadjuvant hormonal therapy improves oncological outcomes of patients with localized prostate cancer treated with permanent brachytherapy.

METHODS

Between January 2004 and November 2014, 564 patients underwent transperineal ultrasonography-guided permanent iodine-125 seed brachytherapy. We retrospectively analyzed low- or intermediate-risk prostate cancer based on the National Comprehensive Cancer Network guidelines. The clinical variables were evaluated for influence on biochemical recurrence-free survival, progression-free survival, cancer-specific survival and overall survival.

RESULTS

A total of 484 patients with low-risk (259 patients) or intermediate-risk disease (225 patients) were evaluated. Of these, 188 received neoadjuvant hormonal therapy. With a median follow up of 71 months, the 5-year actuarial biochemical recurrence-free survival rates of patients who did and did not receive neoadjuvant hormonal therapy were 92.9% and 93.6%, respectively (P = 0.2843). When patients were stratified by risk group, neoadjuvant hormonal therapy did not improve biochemical recurrence-free survival outcomes in low- (P = 0.8949) or intermediate-risk (P = 0.1989) patients. The duration or type of hormonal therapy was not significant in predicting biochemical recurrence. In a multivariate analysis, Gleason score, pretreatment prostate-specific antigen, clinical T stage, and prostate dosimetry, primary Gleason score and positive core rate were significant predictive factors of biochemical recurrence-free survival, whereas neoadjuvant hormonal therapy was insignificant. Furthermore, neoadjuvant hormonal therapy did not significantly influence progression-free survival, cancer-specific survival or overall survival.

CONCLUSIONS

In patients with low- or intermediate-risk disease treated with permanent prostate brachytherapy, neoadjuvant hormonal therapy does not improve oncological outcomes. Its use should be restricted to patients who require prostate volume reduction.

Automatic Detection and Quantitative DCE-MRI Scoring of Prostate Cancer Aggressiveness

Purpose

To develop a robust and clinically applicable automated method for analyzing Dynamic Contrast Enhanced (DCE-) MRI of the prostate as a guide for targeted biopsies and treatments.

Materials and methods

An unsupervised pattern recognition (PR) method was used to analyze prostate DCE-MRI from 71 sequential radiotherapy patients. Identified regions of interest (ROIs) with increased perfusion were assigned either to the peripheral (PZ) or transition zone (TZ). Six quantitative features, associated with the washin and washout part of the weighted average DCE curve from the ROI, were calculated. The associations between the assigned DCE-scores and Gleason Score (GS) were investigated. A heatmap of tumor aggressiveness covering the entire prostate was generated and validated with histopathology from MRI-ultrasound fused (MRI-US) targeted biopsies.

Results

The volumes of the PR-identified ROI’s were significantly correlated with the highest GS from the biopsy session for each patient. Following normalization (and only after normalization) with gluteus maximus muscle’s DCE signal, the quantitative features in PZ were significantly correlated with GS. These correlations straightened in subset of patients with available MRI-US biopsies when GS from the individual biopsies were used. Area under the receiver operating characteristics curve for discrimination between indolent vs aggressive cancer for the significant quantitative features reached 0.88–0.95. When DCE-scores were calculated in normal appearing tissues, the features were highly discriminative for cancer vs no cancer both in PZ and TZ. The generated heatmap of tumor aggressiveness coincided with the location and GS of the MRI-US biopsies.

Conclusion

A quantitative approach for DCE-MRI analysis was developed. The resultant map of aggressiveness correlated well with tumor location and GS and is applicable for integration in radiotherapy/radiology imaging software for clinical translation.

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.

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.

Prostate cancer radiomics and the promise of radiogenomics

Prostate cancer exhibits intra-tumoral heterogeneity that we hypothesize to be the leading confounding factor contributing to the underperformance of the current pre-treatment clinical-pathological and genomic assessment. These limitations impose an urgent need to develop better computational tools to identify men with low risk of prostate cancer versus others that may be at risk for developing metastatic cancer. The patient stratification will directly translate to patient treatments, wherein decisions regarding active surveillance or intensified therapy are made. Multiparametric MRI (mpMRI) provides the platform to investigate tumor heterogeneity by mapping the individual tumor habitats. We hypothesize that quantitative assessment (radiomics) of these habitats results in distinct combinations of descriptors that reveal regions with different physiologies and phenotypes. Radiogenomics, a discipline connecting tumor morphology described by radiomic and its genome described by the genomic data, has the potential to derive "radio phenotypes" that both correlate to and complement existing validated genomic risk stratification biomarkers. In this article we first describe the radiomic pipeline, tailored for analysis of prostate mpMRI, and in the process we introduce our particular implementations of radiomics modules. We also summarize the efforts in the radiomics field related to prostate cancer diagnosis and assessment of aggressiveness. Finally, we describe our results from radiogenomic analysis, based on mpMRI-Ultrasound (MRI-US) biopsies and discuss the potential of future applications of this technique. The mpMRI radiomics data indicate that the platform would significantly improve the biopsy targeting of prostate habitats through better recognition of indolent versus aggressive disease, thereby facilitating a more personalized approach to prostate cancer management. The expectation to non-invasively identify habitats with high probability of housing aggressive cancers would result in directed biopsies that are more informative and actionable. Conversely, providing evidence for lack of disease would reduce the incidence of non-informative biopsies. In radiotherapy of prostate cancer, dose escalation has been shown to reduce biochemical failure. Dose escalation only to determinate prostate habitats has the potential to improve tumor control with less toxicity than when the entire prostate is dose escalated.

Treatment trends for clinically localised prostate cancer. National population analysis: GESCAP group

OBJECTIVES

To describe the established therapies for localised prostate cancer (PC) in Spain and to assess compliance with the 2010 UAE guidelines.

PATIENTS AND METHODS

This was an epidemiological, observational, prospective and multicentre study. Of the 3,918 patients diagnosed with PC during 2010, only those patients with localised PC were included. Follow-up was ultimately conducted for a minimum of one year from the diagnosis for 3,713 patients (94.77%). The treatment groups assessed were as follows: radical prostatectomy, radiation therapy, hormone therapy, brachytherapy, active surveillance or observation and experimental local treatment (cryotherapy or other treatment). Compliance with the recommendations of the EAU guidelines was studied, describing the treatment groups according to D'Amico risk stratification criteria (localised [low, intermediate and high risk] and locally advanced), age, PSA and Gleason score.

RESULTS

By applying the D'Amico criteria, we included 3,641 (92.93%) patients. Based on the UAE recommendations: 1) 68.87% of the patients at low-intermediate risk aged≤65 years underwent radical prostatectomy; 2) 34.51% of the patients>65 years at high risk with locally advanced disease were administered radiation therapy and hormone therapy; 3) 30.36% of the patients at high risk with locally advanced disease were only treated with hormone therapy; 4) 15.20% of the patients at low risk were only treated with brachytherapy; 5) active surveillance or observation was selected for 2.44% of the patients aged≤65 years and for 10.63% of the patients at low-intermediate risk who were>65 years. Lastly, 86.5% of the patients at low risk underwent a single treatment, and 43.62% of the patients at high risk with locally advanced disease underwent combined treatments.

CONCLUSIONS

This is the first national European study to evaluate the therapeutic management of localised PC based on the risk group to which the patient belonged. Most young patients (≤65 years) with low-intermediate risk localised PC were treated with surgery, which adheres to the recommendations of the 2010 UAE guidelines. Various therapeutic combinations have been employed for patients with high-risk, locally advanced localised tumours, revealing the need for a multidisciplinary approach (Controlled-trials.com number: ISRCTN19893319).

Permanent prostate brachytherapy using high V150

PURPOSE

Prostate brachytherapy sometimes requires the volume receiving >150% of the prescribed dose (V150) to be >50% to obtain satisfactory coverage. There has been concern expressed that high V150 may be associated with higher rates of urinary retention and morbidity.

METHODS AND MATERIALS

We reviewed 207 consecutive cases of prostate brachytherapy treated with palladium 103 ((103)Pd; n = 140) or iodine 125 ((125)I; n = 67). Prescribed doses for (103)Pd monotherapy and boost were 124 and 90 Gy, respectively; for (125)I, the corresponding doses were 160 and 120 Gy. Patients were evaluated at baseline, 1 month, 3 months, and every 6 months thereafter.

RESULTS

Median follow-up at the time of analysis was 18 months. For (103)Pd, the mean intraoperative volume and V150 were 30.3 cm(3) and 72%, respectively; corresponding values for (125)I were 38.3 cm(3) and 59%, respectively. Two of the patients treated with iodine and 9 treated with palladium experienced acute urinary retention, which was not statistically significant (P = .48). The rectal V100 for (103)Pd was significantly less than that for (125)I (P < .001). The mean baseline, 1-month, and 12-month American Urologic Association (AUA) scores for (103)Pd were 8.5, 19.7, and 8.2, respectively; for (125)I, the values were 7.4, 17.1, and 13.4, respectively. At 12 months, the AUA scores returned to baseline in the (103)Pd-treated patients, whereas scores in (125)I-treated patients remained elevated (P = .005). High V150 did not appear to cause undue risk of urinary retention or morbidity based on logistic regression analysis of patients treated with monotherapy performed with either isotope.

CONCLUSIONS

The risk of urinary retention was low, despite high V150 values for both isotopes. In patients treated with brachytherapy alone, no significant increase in urinary morbidity was seen in relation to V150. AUA scores returned to baseline in (103)Pd-treated patients at 1 year, whereas (125)I-treated patients demonstrated continued elevation.

How to select the optimal therapy for early-stage prostate cancer

Selecting the "optimal therapy" for the patient with localized prostate cancer may be one of the most challenging medical decisions facing the oncologist. Most patients will have a number of appropriate therapeutic options available to them. Before determining which therapy is most appropriate for a patient, a critical question which needs to be asked is whether any therapy is necessary, especially for those who present with early-stage, low-grade, low-volume disease. Furthermore, given the lack of randomized trials available to guide physicians regarding the superiority of one therapy over another, it is important to consider the different side-effect profiles relevant for each treatment modality. The potential toxicities of therapy impact quality-of-life outcomes and play an important role for most patients in their individual selection of a particular therapy. In addition, there are other important issues that need to be considered, which include the medical condition of the patient and emotional and psychological considerations, as well as family/peer viewpoints or perceived notions of a particular therapy. This review will discuss the relevant issues in the decision making and treatment selection for the patient.

A comparison of the impact of isotope ((125)I vs. (103)Pd) on toxicity and biochemical outcome after interstitial brachytherapy and external beam radiation therapy for clinically localized prostate cancer

PURPOSE

To compare biochemical outcomes and morbidity associated with iodine-125 ((125)I) and palladium-103 ((103)Pd) brachytherapy as part of combined modality therapy for clinically localized prostate cancer.

METHODS AND MATERIALS

Between October 2002 and December 2008, 259 patients underwent prostate brachytherapy ((125)I prescription dose, 110Gy: n=199; (103)Pd prescription dose, 100Gy: n=60) followed by external beam radiotherapy (median dose, 50.4Gy). Eighty-seven patients also received neoadjuvant androgen deprivation therapy. Toxicities were recorded with CTCAE v 3.0, International Prostate Symptoms Score (IPSS), and International Index of Erectile Function questionnaires.

RESULTS

Overall, acute Grade ≥2 genitourinary toxicity occurred in 21% and 30% of patients treated with (125)I and (103)Pd, respectively (p=0.16). There were no significant differences in IPSS change or urinary quality-of-life scores between the isotopes at 4, 6, or 12 months (p=0.20, 0.21, and 1.0, respectively). IPSS resolution occurred at a median of 11 and 6 months for (125)I and (103)Pd patients, respectively (p=0.03). On multivariate analysis, only the use of neoadjuvant androgen deprivation therapy was predictive of time to IPSS resolution (p=0.046). Late Grade ≥2 gastrointestinal toxicity occurred in 7% of (125)I patients and 6% of patients treated with (103)Pd. Of 129 potent patients at baseline, there was better erectile function in patients who received (103)Pd (p=0.02); however, the followup was shorter for these patients. The 5-year prostate-specific antigen relapse-free survival for (125)I and (103)Pd patients was 95.2% and 98.2% (p=0.73), respectively.

CONCLUSION

There were no differences in acute or long-term genitourinary or gastrointestinal toxicity between (125)I and (103)Pd in combined modality therapy for prostate cancer. There may be less erectile toxicity with the use of (103)Pd; however, additional followup of these patients is needed. There was no significant difference in 5-year prostate-specific antigen relapse-free survival between (103)Pd and (125)I.

Predictors in the outcome of 125I brachytherapy as monotherapy for prostate cancer

A number of different prostate cancer treatment modalities exist. Nomograms are used to assist clinicians and patients in choosing the most appropriate treatment. However, the predicted outcome for (125)I brachytherapy is much worse than what would be expected considering the actual survival rates. This underestimation may result in suboptimal treatment decisions. Therefore, better predictors for outcome after (125)I brachytherapy are necessary. The following factors, which may either influence outcome or predict outcome after brachytherapy, are discussed: tumor characteristics and risk stratification, patient age at treatment, obesity, adjuvant androgen-deprivation therapy, prostate-specific antigen bounce, implantation technique and dosimetry. For the prediction of outcome after (125)I brachytherapy, as long as the quality of the implant is optimal, only high-risk prostate cancer was found to have a negative impact on outcome.