Low Dose Rate Prostate Brachytherapy Research Articles

The Effect of Dose and Quality Assurance in Early Prostate Cancer Treated with Low Dose Rate Brachytherapy as Monotherapy

AimsTo examine the relationship between post-implant computed tomography dosimetry and long-term prostate-specific antigen relapse-free survival in patients treated with iodine 125 (I-125) low dose rate prostate brachytherapy as monotherapy and, second, to audit recent practice against Royal College of Radiologists' (RCR) guidelines after the re-introduction of post-implant dosimetry for all patients in our centre. Materials and methodsBetween March 1995 and September 2007, 2157 consecutive patients with localised prostate cancer underwent I-125 permanent prostate brachytherapy as monotherapy in a single UK centre. All patients were transrectal ultrasound planned delivering a 145 Gy (TG 43) minimum peripheral dose. None received supplemental external beam radiotherapy. Post-implant computed tomography-based dosimetry was undertaken between 4 and 6 weeks after treatment and was available for 711 (33%). Outcomes were analysed in terms of the relationship of D90 to prostate-specific antigen relapse-free survival (nadir 2+ definition) and all patients had a minimum follow-up of 5 years. For contemporary patients from 2011, quality metrics from post-implant computed tomography as defined by RCR guidelines are presented. ResultsA mean D90 of 138.7 Gy (standard deviation 24.7) was achieved for the historic cohort. Biochemical control at 10 years was 76% in patients with D90 > 140 Gy and 68% in those with D90 < 140 Gy (P < 0.01). In current practice, over the last 3 years the mean (standard deviation) D90 has increased from 154 (15.3) Gy in 2011 to 164 (13.5) Gy in 2013. Similarly, an increase in the mean (standard deviation) V100 from 92 (4.4) to 95 (3.2) % is noted over time. No difference between clinicians was noted. ConclusionD90 values of less than 140 Gy continue to be predictive of increased risk of recurrence of prostate cancer across risk groups with longer follow-up. Quality assurance can be used to ensure improved and consistent implant quality in a team with multiple clinicians.

Patterns of Recurrence After Low-Dose-Rate Prostate Brachytherapy: A Population-Based Study of 2223 Consecutive Low- and Intermediate-Risk Patients

This study examined patterns of recurrence after low-dose-rate prostate brachytherapy (LDR-PB), estimated local recurrence rate and compared that rate to the estimated local recurrence rate after radical prostatectomy (RP). A prospective database was maintained with clinical, dosimetric, and outcome data for all LDR-PB implantation procedures performed at our institution. From 1998 to 2008, 2223 patients with prostate cancer received LDR-PB without supplemental external beam radiation therapy. Patients who developed Phoenix-defined biochemical failure were reviewed for sites of relapse and investigations completed. At a median follow-up of 5 years, 108 of 2223 patients (4.8%) developed biochemical relapse. In 1 additional patient, local relapse was found on transurethral prostate resection, but his prostate-specific antigen concentration was well short of triggering Phoenix-defined failure. Of the 109 patients with disease relapse, 18 of 2223 (0.8%) had a proven local recurrence, and 30 of 2223 (1.3%) had a proven distant recurrence. The remaining 61 of 2223 patients (2.7%) had unidentified sites of recurrence; of these, 57 patients (93%) had digital rectal examinations (DREs), 18 (30%) had post-treatment biopsies, 45 (74%) had bone scans, and 34 (56%) had computed tomography imaging of the abdomen and pelvis. If every biochemical failure were local, the local recurrence rate would be as high as 4.9%; however, by excluding those with proven distant failure and those with both a negative DRE and biopsy, we estimate that the local recurrence rate is 2.7% or less. In the context of limitations of the study design, our population-based analysis indicates that the local recurrence rate after LDR-PB is as low or lower than that after RP in our jurisdiction.

Calcifications in low-dose rate prostate seed brachytherapy treatment: Post-planning dosimetry and predictive factors

Background and purposeThe brachytherapy dose algorithm of the American Association of Physicists in Medicine Task Group (TG) Report 43 overrides all tissue materials with water. In reality, dose discrepancies will occur around tissue calcifications. This study investigates these perturbations in low dose rate prostate brachytherapy dosimetry. Materials and methods43 cancer patients with prostatic calcifications are identified. Geant4 Monte Carlo (MC) simulations are made with materials assigned based on TG186 recommendations. Five dose calculation scenarios are presented: MC in water (MCW), MCW with calcifications, (MCCA), MCCA with seeds (MCCASEED) and full tissue definition and seeds with dose to medium in medium (FMC) and dose to water in medium (FMC-Dw,m). ResultsThe mean FMC prostate D90 (V100) difference relative to TG43 is −6.4% (range [−1.8, −14.1]) (−2.6% [−0.3, −6.7]). For MCCA we obtained −3.9% [−1.0, −8.7] (−1.5% [−0.2, −4.1]). The mean urethra D10 difference is −4.5% [−1.3, −9.9] for FMC, −2.4% [−0.7, −5.1] with MCCA. FMC-Dw,m D90 has a −0.45% smaller dose difference than FMC on average. The calcification/prostate volume ratio is a good predictor of dose perturbation (R2=0.75). ConclusionBased on these results, calcifications alter the dose coverage and may have severe dose perturbation that requires recalculation.

A review of rectal toxicity following permanent low dose-rate prostate brachytherapy and the potential value of biodegradable rectal spacers.

Permanent radioactive seed implantation provides highly effective treatment for prostate cancer that typically includes multidisciplinary collaboration between urologists and radiation oncologists. Low dose-rate (LDR) prostate brachytherapy offers excellent tumor control rates and has equivalent rates of rectal toxicity when compared with external beam radiotherapy. Owing to its proximity to the anterior rectal wall, a small portion of the rectum is often exposed to high doses of ionizing radiation from this procedure. Although rare, some patients develop transfusion-dependent rectal bleeding, ulcers or fistulas. These complications occasionally require permanent colostomy and thus can significantly impact a patient's quality of life. Aside from proper technique, a promising strategy has emerged that can help avoid these complications. By injecting biodegradable materials behind Denonviller's fascia, brachytherpists can increase the distance between the rectum and the radioactive sources to significantly decrease the rectal dose. This review summarizes the progress in this area and its applicability for use in combination with permanent LDR brachytherapy.

An Analysis of the Impact on Trends in Automation on Human Error Potential in Brachytherapy

Technologies under development in the field of radiotherapy offer the possibility of automating many of the remaining functions that are currently carried out by radiotherapy staff. If adopted, they are likely to significantly change the roles of health care professionals and modify the potential error profile of specific radiotherapy procedures. In this paper, a combination of allocation of functions methods, including Levels of Automation (LOA) [1] and Meister's prescriptive method [2], and the Human Error Analysis and Reduction Technique (HEART) [3] were used as the basis for an evaluation of the impact of increasing automation on the potential for human error in Low-Dose Rate Prostate Brachytherapy (LDRPB). An IDEFØ model of the brachytherapy treatment process previously developed by the authors was the starting point for the analysis. The process “Perform Implant” which currently has sub-processes that are under direct human control and others that utilize advanced technology was selected for analysis. The LOA model was applied to “Perform Implant” for three scenarios: current set-up, mixed-automaton and full automation. A modified set of risk criteria specified by the Irish Health Service Executive (HSE) [4] were used in conjunction with Meister's method to select the most appropriate mix of automation for further analysis. HEART was then applied to both the current set-up scenario and the selected scenario and the outcomes were compared. The HEART analysis provided one justification for the selection of a particular human-automation mix, though caution should be exercised as HEART requires further validation in the context of healthcare systems.

Impact of Race on Both Pathologic Extent of Disease and Administration of Adjuvant Radiation Therapy in a Cohort With Clinical Low-Risk Prostate Cancer Undergoing Radical Prostatectomy

Purpose/Objective(s): Androgen deprivation therapy (ADT) and standard dose external beam radiation therapy ( 70 Gy) have improved biochemical outcomes in intermediate risk (IR) prostate cancer. It is not known whether ADT improves outcomes in patients treated with brachytherapy. Our purpose is to evaluate the impact of ADT on biochemical failure free survival (bFFS) and overall survival (OS) in a multi-institutional database of IR prostate cancer patients treated with low dose rate prostate brachytherapy (LDR BT). Materials/Methods: From the Genitourinary Radiation Oncologists of Canada (GUROC) Prostate Cancer Risk Stratification (ProCaRS) database, a cohort of 859 patients with IR prostate cancer treated with LDR BTwith or without ADT was identified. Propensity scores were generated using multivariate regression based on age, baseline PSA, Gleason score and clinical stage. Patients treated with LDR alone were each matched to 2 patients who received the combination of LDR and ADT. Results: A 1:2 matching scenario (175 LDR BT : 350 LDR BT+ADT) provided the best balance of adjusted prognostic factors, a larger sample size than obtained with 1:1 matching, and standardized differences< 0.1 for prognostic factors used for matching. The 2 groups were balanced for age, baseline PSA, Gleason score and clinical stage. Median follow-up was longer in the LDR BT+ADT group (7.15 vs 4.21 years). After matching, there was no difference in bFFS (relative risk LDRBT+ADTZ 0.87, 95%CIZ 0.50-1.53); however, OS was worse in the group receiving ADT (relative risk LDR BT+ADT Z 2.83, 95%CIZ 1.00-7.98). Furthermore, a trend towardsworse cancer-related survival was observed for the LDR BT+ADT group (p Z 0.095). Conclusions: These results suggest that ADT does not benefit bFFS or OS in IR patients treated with LDR BT. Prospective studies are needed to investigate the role of ADT in IR prostate cancer patients treated with LDR BT. Author Disclosure: J. Rose: None. J.M. Crook: None. Y. Yang: None. A. Warner: None. J. Morris: None. T. Pickles: None. A. Martin: None. E. Vigneault: None. C. Catton: None. G. Rodrigues: None.

Androgen Deprivation Therapy in Intermediate-Risk Prostate Cancer Patients Treated With Low-Dose-Rate Brachytherapy: A Multi-institutional Propensity Score Matched Pair Analysis

Androgen deprivation therapy (ADT) and standard dose external beam radiation therapy (≤ 70 Gy) have improved biochemical outcomes in intermediate risk (IR) prostate cancer. It is not known whether ADT improves outcomes in patients treated with brachytherapy. Our purpose is to evaluate the impact of ADT on biochemical failure free survival (bFFS) and overall survival (OS) in a multi-institutional database of IR prostate cancer patients treated with low dose rate prostate brachytherapy (LDR BT).

The Cancer of the Prostate Risk Assessment (CAPRA) score predicts biochemical recurrence in intermediate-risk prostate cancer treated with external beam radiotherapy (EBRT) dose escalation or low-dose rate (LDR) brachytherapy

To study the prognostic value of the University of California, San Francisco Cancer of the Prostate Risk Assessment (CAPRA) score to predict biochemical failure (bF) after various doses of external beam radiotherapy (EBRT) and/or permanent seed low-dose rate (LDR) prostate brachytherapy (PB). We retrospectively analysed 345 patients with intermediate-risk prostate cancer, with PSA levels of 10-20 ng/mL and/or Gleason 7 including 244 EBRT patients (70.2-79.2 Gy) and 101 patients treated with LDR PB. The minimum follow-up was 3 years. No patient received primary androgen-deprivation therapy. bF was defined according to the Phoenix definition. Cox regression analysis was used to estimate the differences between CAPRA groups. The overall bF rate was 13% (45/345). The CAPRA score, as a continuous variable, was statistically significant in multivariate analysis for predicting bF (hazard ratio [HR] 1.37, 95% confidence interval [CI] 1.10-1.72, P = 0.006). There was a trend for a lower bF rate in patients treated with LDR PB when compared with those treated by EBRT ≤ 74 Gy (HR 0.234, 95% CI 0.05-1.03, P = 0.055) in multivariate analysis. In the subgroup of patients with a CAPRA score of 3-5, CAPRA remained predictive of bF as a continuous variable (HR 1.51, 95% CI 1.01-2.27, P = 0.047) in multivariate analysis. The CAPRA score is useful for predicting biochemical recurrence in patients treated for intermediate-risk prostate cancer with EBRT or LDR PB. It could help in treatment decisions.

Placement of empty catheters for an HDR-Emulating LDR Prostate Brachytherapy technique: Comparison to standard intraoperative planning

We sought to determine whether placing empty catheters within the prostate and then inverse planning iodine-125 seed locations within those catheters (High Dose Rate-Emulating Low Dose Rate Prostate Brachytherapy [HELP] technique) would improve concordance between planned and achieved dosimetry compared with a standard intraoperative technique. We examined 30 consecutive low dose rate prostate cases performed by standard intraoperative technique of planning followed by needle placement/seed deposition and compared them to 30 consecutive low dose rate prostate cases performed by the HELP technique. The primary endpoint was concordance between planned percentage of the clinical target volume that receives at least 100% of the prescribed dose/dose that covers 90% of the volume of the clinical target volume (V100/D90) and the actual V100/D90 achieved at Postoperative Day1. The HELP technique had superior concordance between the planned target dosimetry and what was actually achieved at Day 1 and Day 30. Specifically, target D90 at Day 1 was on average 33.7Gy less than planned for the standard intraoperative technique but was only 10.5Gy less than planned for the HELP technique (p < 0.001). Day 30 values were 16.6Gy less vs. 2.2Gy more than planned, respectively (p= 0.028). Day 1 target V100 was 6.3% less than planned with standard vs. 2.8% less for HELP (p < 0.001). There was no significant difference between the urethral and rectal concordance (all p > 0.05). Placing empty needles first and optimizing the plan to the known positions of the needles resulted in improved concordance between the planned and the achieved dosimetry to the target, possibly because of elimination of errors in needle placement.

Distinguishing Prostate-Specific Antigen Bounce from Biochemical Failure after Low-Dose-Rate Prostate Brachytherapy

Low-dose-rate (LDR) brachytherapy is a popular treatment option for men with localized prostate cancer. Patient outcomes are excellent, with minimal toxicity and excellent disease-free survival. However, temporary increases in prostate-specific antigen (PSA) levels are common after brachytherapy, a phenomenon known as a benign PSA bounce. The purpose of this study was to characterize PSA rises of at least 2.0 ng/mL as benign bounces or biochemical failures after LDR prostate brachytherapy at our institution, and to investigate distinguishing features between them.

Does dose matter? Editorial comments to Morris et al. Whole prostate D90 and V100: A dose–response analysis of 2000 consecutive 125I monotherapy cases

In this issue of Brachytherapy, Morris et al. ( [1] Morris W.J. Spadinger I. Keyes M. et al. Whole prostate D90 and V100: A dose-response analysis of 2000 consecutive 125-Iodine monotherapy cases. Brachytherapy. 2014; 13: 32-41 Abstract Full Text Full Text PDF Scopus (30) Google Scholar ) reviewed their experience with 2000 consecutive 125I prostate implants to determine which pretreatment- and treatment-related factors influenced prostate-specific antigen (PSA; Phoenix) control. In this group of low- and intermediate-risk patients with a median followup of 5 year, the 5-, 7-, and 10-year actuarial disease-free survival (DFS) estimates were 96.0%, 94.4%, and 93.0%, respectively. Based on their analyses, they concluded “that dose metrics are not equivalent to oncologic endpoints and must be calibrated against DFS for each physician and each institution offering low-dose-rate prostate brachytherapy.” The obvious question is “does dose matter?” Because there is ample evidence that higher radiation doses improve biochemical and local control after external beam radiation therapy, maybe the question should be narrowed to “does dose only matter for 125I prostate implants?” Rebuttal to Drs Stone and StockBrachytherapyVol. 13Issue 1Preview“… a man hears what he wants to hear and disregards the rest …”The Boxer, 1969, lyrics by Paul Simon Full-Text PDF Whole prostate D90 and V100: A dose–response analysis of 2000 consecutive 125I monotherapy patientsBrachytherapyVol. 13Issue 1PreviewTo examine the relationship between whole prostate dose metrics and disease-free survival (DFS) after 125I low-dose-rate prostate brachytherapy (LDR-PB). Full-Text PDF

Prostate-Specific Antigen at 4 to 5 Years After Low-Dose-Rate Prostate Brachytherapy Is a Strong Predictor of Disease-Free Survival

To determine (1) the prognostic utility of prostate-specific antigen (PSA) concentration at 45 to 60 months (48mPSA) after low-dose-rate prostate brachytherapy (LDR-PB); (2) the predictors of 48mPSA; and (3) the prognostic utility of directional trends between PSA levels at 24, 36, and 48 months after LDR-PB. Between 1998 and 2008, 2223 patients with low- and intermediate-risk prostate cancer received LDR-PB monotherapy. A cohort of 1434 of these patients was identified with a documented 48mPSA and no evidence of disease relapse prior to the 48mPSA. In addition, a subset of this cohort (n=585) was identified with ≥72 months of follow-up and documented PSA values at both 24 and 36 months after implantation. Median follow-up time was 76 months. Eight-year Kaplan-Meier disease-free survival (DFS) rates were 100% vs 73.4% for patients with 48mPSA≤0.2 vs those with >0.2 ng/mL; 99.1% versus 53.8% for a 48mPSA threshold of ≤0.4 versus >0.4 ng/mL, respectively; and 97.3% versus 0% for a threshold of ≤1.0 versus >1.0 ng/mL, respectively. On multivariate analysis, the only factor predictive of DFS was 48mPSA (P<.0001). On subset analysis (n=585), 29 patients had a PSA rise (defined as >0.2 ng/mL) between 24 and 36 months, 24 patients had a rise between 36 and 48 months, and 11 patients had rises over both intervals. Failure rates in these patients were 52%, 79%, and 100%, respectively. On multivariate analysis, initial PSA, androgen deprivation therapy, and dose to 90% of the prostate significantly correlated with 48mPSA but together accounted for only ∼5% of its total variance. The 48mPSA after LDR-PB is highly predictive of long-term DFS. Patients with 48mPSA≤0.4 ng/mL had a <1% risk of disease relapse at 8 years, whereas all patients with 48mPSA>1.0 ng/mL relapsed. Consecutive PSA rises of >0.2 ng/mL from 24 to 36 months and from 36 to 48 months were also highly predictive of subsequent failure.

Whole prostate D90 and V100: A dose–response analysis of 2000 consecutive 125I monotherapy patients

To examine the relationship between whole prostate dose metrics and disease-free survival (DFS) after (125)I low-dose-rate prostate brachytherapy (LDR-PB). Data for the first 2000 LDR-PB monotherapy implants were extracted from a database containing patient, tumor, dosimetric, and outcomes information. By National Comprehensive Cancer Network criteria, half (n = 1006) had low-risk disease and half (n = 990) had intermediate-risk disease (four had high-risk disease). Most patients (58.4%) and 75.3% of intermediate-risk patients received 3 months neoadjuvant and 3 months concomitant androgen deprivation therapy (ADT). Univariate and multivariate analyses were conducted using recognized prognostic factors and the whole prostate dose metrics D90 (the minimum dose received by 90% of the postimplant CT-based prostate volume) and V100 (the percent of the postimplant CT-based prostate volume that received at least 100% of the prescription dose). The median followup is 5 years (maximum, 12.5 years); the 5-, 7-, and 10-year actuarial DFS estimates are 96.0%, 94.4%, and 93.0%, respectively. Of the recognized prognostic factors, only pretreatment prostate-specific antigen (p = 0.012) and Gleason sum (p = 0.010) were predictive of DFS. When analyzed as continuous variables, dose metrics were not predictive of DFS. However, most nonsignificant trends favored higher doses, and D90 values <130 Gy were predictive of an increased risk of recurrence in the non-ADT subset (N = 833; log rank, p = 0.018). Although D90 values of <130 Gy were predictive of an increased risk of recurrence in the non-ADT subset, neither D90 nor V100, when used as continuous variables, was predictive of DFS when applied to the entire cohort or in the subset analysis. This observation informs us that dose metrics are not equivalent to oncologic end points and must be calibrated against DFS for each physician and each institution offering LDR-PB.

Quantitative Evaluation of Neurovascular Bundle Doses in Low-Dose-Rate Prostate Brachytherapy Using I-125 Seeds

Low dose rate (LDR) prostate brachytherapy is an accepted standard treatment technique for early and intermediate stage prostate cancer. Several studies have reported impotence risk after brachytherapy which may result from dose delivered to neurovascular bundles (NVB). The purpose of this work is to investigate retrospectively the dose delivered to NVB and its potential correlation with erectile dysfunction. Treatment planning and seed implantation techniques that provide optimized doses to NVB are also investigated. The records of ten patients treated with a monotherapy prescription dose of 144 Gy using I-125 implanted seeds were reviewed. Transverse endorectal ultrasound (US) images were obtained and used to contour prostate, urethra and rectum at the start of the procedure with patient in dorsal lithotomy position and under anesthesia using a transrectal US probe. As part of our procedure, NVB were localized using Doppler US imaging on the right and left sides of prostate. An inversely optimized treatment plan was generated using current patient structures. A dose coverage of more than 98% of prostate volume to prescription dose of 144 Gy (V100 = 98-100%) and sparing of 95% of the rectum and urethra volumes as critical structures from 150% dose (V150 < 5%) were achieved in initial plan that is used in the procedure and modified intraoperatively during seed implantation. The mean and standard deviation of the maximum, minimum and mean dose delivered to left and right neurovascular bundles are shown in Table for actual implanted procedures. The dose to NVB correlated strongly with prostate D90 where high D90 implants resulted in high NVB dose, particularly for hot implants in the posterior section of prostate that sided with tumor foci. The mean left NVB dose was 167.96 Gy which is often higher than the prescription dose. Retrospective optimization of the treatment plans of implanted prostates improved substantially the sparing of NVB, for example, the mean of the maximum dose was decreased to half the value compared to non-optimized plans. This study demonstrated that NVB received high mean doses in prostate brachytherapy that was not optimized for NVB doses. The NVB can be spared to lower dose levels if their dose coverage was constrained using dynamic intraoperative inverse planning. Future follow-up study will investigate correlation between the doses delivered to NVB and erectile dysfunction.Poster Viewing Abstract 2481; TableMean and standard deviation of the maximum, minimum and mean dose of the right and left NVBRight NVBLeft NVBMean (Gy)Standard dev. (Gy)Mean (Gy)Standard dev. (Gy)Volume (CC)0.22400.05720.18800.0581Max. dose294.29101.16364.17158.79Min. dose61.7628.0071.0437.69Mean dose128.8725.49167.9651.89 Open table in a new tab

Pride or prejudice: Does Phoenix flatter radiation therapy?

To compare disease-free survival (DFS) rates using a >0.4ng/mL biochemical failure definition with the Phoenix (nadir+2ng/mL) failure definition by analyzing a consecutive cohort of 1006 patients treated with low-dose-rate prostate brachytherapy (LDR-PB) monotherapy. Data for first 1006 consecutive LDR-PB implants (1998-2003) were extracted from a prospective database. Patients had low- (58%) or intermediate (42%)-risk disease. Three months neoadjuvant and 3months concomitant androgen deprivation therapy were used in 65% of cases. The Phoenix definition was modified to "unfail" patients who had a benign prostate-specific antigen (PSA) bounce. The median followup is 7.5years. The median PSA at latest followup for disease-free patients was 0.04ng/mL. The Phoenix definition yielded 5- and 10-year Kaplan-Meier DFS estimates of 96.5 ± 1.2% and 93.7 ± 2.0%, respectively. Applying the >0.4ng/mL threshold reduced these estimates to 94.4 ± 1.6% and 88.8 ± 3.0% (log rank, p=0.015). Compared with Phoenix, applying a >0.4ng/mL failure definition increased biochemical failure by ∼2% at 5years and ∼5% at 10years. These data show that Phoenix did not greatly exaggerate DFS estimates compared with a surgical-type threshold. However, this observation is a consequence of the exceptionally low residual PSA values characteristic of LDR-PB and cannot be generalized to other forms of radiation therapy.

Boost Versus Monotherapy: A Propensity-Score Matched-Pair Analysis of High-Dose-Rate Brachytherapy with or without External Beam Radiotherapy for Low- and Intermediate-Risk Prostate Cancer

physicians have advocated a primary surgical approach in young patients. The purpose of this study was to evaluate the long-term outcomes of lowdose-rate (LDR) prostate brachytherapy based treatment in this younger cohort of patients. Materials and Methods: Four thousand men have undergone prostate seed implantation at our institution since July 1997. All patients are followed prospectively in our IRB-approved database and assessed for clinical and biochemical recurrence based on the Phoenix definition. Risk stratification was assigned per NCCN guidelines. Patients with initial PSA O50 were not included in this analysis. This analysis reviews 170 consecutive patients treated at ages #55 years old. Twenty-two percent of patients were treated with LDR Iodine-125 seed implant monotherapy, and 78% Palladium-103 seed implant combined with 45 Gray external radiation. Seed implants were performed using a dynamic intraoperative dosimetry technique. Combination therapy was primarily employed in intermediateand high-risk groups. Sixty percent of patients received short course hormone therapy for a median duration of 6 months. Results: With a median followup of 80 months, 94% of all patients were free from biochemical failure (FFBF). On subset analysis, 98% of lowrisk, 95% of intermediate-risk, and 84% of high-risk patients were FFBF. Grade 3 complications occurred in only 2.9% of patients. These consisted mostly of urinary retention and its subsequent management. No grade 4 complications occurred. Conclusions: Prostate seed implant based treatments resulted in excellent long-term outcomes with minimal morbidity in this young cohort of patients. These results compared favorably to surgical and other series.

Curiethérapie exclusive du cancer de la prostate par implants permanents : indications et résultats. Revue du CC-AFU

To summarize the indications and outcomes of low dose-rate prostate brachytherapy with permanent implants. Bibliographic database PubMed was searched with prostate cancer and brachytherapy as keywords from 1995 to 2012. The main indication of prostate brachytherapy is the favorable group, but it could be proposed to patients with an intermediate prognostic group if the PSA is ≤ 15 ng/mL or if the Gleason score is 7 (3+4), under cover of a prostate MRI without any extra-capsular extension. Oncologic results are similar to those of surgery or external beam irradiation (EBRT), with a 10-yr biochemical control rate approaching 90%. Urinary toxicity is common during the year following the implant, mainly irritative symptoms; 5 to 15% of patients experienced acute urinary retention. A prostate volume higher than 50 cc or an initial high international prostatic symptom score (IPSS) are predictive of toxicity and are recognized as relative contraindications of the technique. Sexual activity is maintained in 60% of patients. Brachytherapy must be proposed as a validated option beside active surveillance, surgery and EBRT.

Assessment of I-125 seed implant accuracy when using the live-planning technique for low dose rate prostate brachytherapy.

BackgroundLow risk prostate cancers are commonly treated with low dose rate (LDR) brachytherapy involving I-125 seeds. The implementation of a ‘live-planning’ technique at the Royal Adelaide Hospital (RAH) in 2007 enabled the completion of the whole procedure (i.e. scanning, planning and implant) in one sitting. ‘Live-planning’ has the advantage of a more reliable delivery of the planned treatment compared to the ‘traditional pre-plan’ technique (where patient is scanned and planned in the weeks prior to implant). During live planning, the actual implanted needle positions are updated real-time on the treatment planning system and the dosimetry is automatically recalculated. The aim of this investigation was to assess the differences and clinical relevance between the planned dosimetry and the updated real-time implant dosimetry.MethodsA number of 162 patients were included in this dosimetric study. A paired t-test was performed on the D90, V100, V150 and V200 target parameters and the differences between the planned and implanted dose distributions were analysed. Similarly, dosimetric differences for the organs at risk (OAR) were also evaluated.ResultsSmall differences between the primary dosimetric parameters for the target were found. Still, the incidence of hotspots was increased with approximately 20% for V200. Statistically significant increases were observed in the doses delivered to the OAR between the planned and implanted data; however, these increases were consistently below 3% thus probably without clinical consequences.ConclusionsThe current study assessed the accuracy of prostate implants with I-125 seeds when compared to initial plans. The results confirmed the precision of the implant technique which RAH has in place. Nevertheless, geographical misses, anatomical restrictions and needle displacements during implant can have repercussions for centres without live-planning option if dosimetric changes are not taken into consideration.

Treatment technique evolution and dosimetry trends over seven years of low dose rate prostate brachytherapy at an Australian institution

Low dose rate prostate brachytherapy treatments began at the Royal Adelaide Hospital (RAH), Australia, in September 2004. This paper will focus on the evolution of treatment technique since then showing how procedural improvements have enabled timely diagnosis of under-dose and scheduling of top-up treatments for sub-optimum implants, and how significant time savings have been achieved for staff and patients. In addition, implant dosimetry trends over this period have been investigated and results are presented. Iodine-125 seeds (Oncura model 6711) have been used since LDR prostate treatments began, with an aim to deliver a prostate dose of 145 Gy. Three key changes in implant technique took place during the period Sept 2004 to Sept 2011. The live implant dosimetry trends of the prostate D90, urethra V150, and rectum D0.1cc and D2.0cc, were assessed to see if the change in technique had an impact on the treatment planning and seed deployment. The switch from manual loading of seeds to pre-loaded needles and the change from a two-step pre-planning procedure to live planning have realized the greatest time savings with approximately 1.0 FTE physicist day saved per 2 patient implant day and 2 patient visits saved per treatment. Dosimetric parameters also improved with mean implant D90s rising from 166 Gy to 180 Gy. The average Urethra D10 also increased over the study group, rising from 186 Gy to 199 Gy while the rectum dose remained unchanged. Both rectum and urethra dose remained below GEC-ESTRO guidelines despite the observed rise in urethral dose.

Radiobiological comparison of single and dual-isotope prostate seed implants

AbstractPurpose: Several isotopes are available for low dose-rate prostate brachytherapy. Currently most implants use a single isotope. However, the use of dual-isotope implants may yield an advantageous combination of characteristics such as half-life and relative biological effectiveness. However, the use of dual-isotope implants complicates treatment planning and quality assurance. Do the benefits of dual-isotope implants outweigh the added difficulty? The goal of this work was to use a linear-quadratic model to compare single and dual-isotope implants.Materials &amp; Methods: Ten patients were evaluated. For each patient, six treatment plans were created with single or dual-isotope combinations of 125I, 103Pd and 131Cs. For each plan the prostate, urethra, rectum and bladder were contoured by a physician. The biologically effective dose was used to determine the tumor control probability and normal tissue complication probabilities for each plan. Each plan was evaluated using favorable, intermediate and unfavorable radiobiological parameters. The results of the radiobiological analysis were used to compare the single and dual-isotope treatment plans.Results: Iodine-125 only implants were seen to be most affected by changes in tumor parameters. Significant differences in organ response probabilities were seen at common dose levels. However, after adjusting the initial seed strength the differences between isotope combinations were minimal.Conclusions: The objective of this work was to perform a radiobiologically based comparison of single and dual-isotope prostate seed implant plans. For all isotope combinations, the plans were improved by varying the initial seed strength. For the optimized treatment plans, no substantial differences in predicted treatment outcomes were seen among the different isotope combinations.