Tumour and target volumes in permanent prostate brachytherapy: A supplement to the ESTRO/EAU/EORTC recommendations on prostate brachytherapy

Associations of Clinical and Dosimetric Parameters with Urinary Toxicities after Prostate Brachytherapy: A Long-Term Single-Institution Experience

To examine the association of clinical, treatment, and dose parameters with late urinary toxicity after low-dose-rate brachytherapy (LDR-BT) for prostate cancer, we retrospectively studied patients with prostate cancer who underwent LDR-BT from January 2007 through December 2016. Urinary toxicity was assessed using the International Prostate Symptom Score (IPSS) and Overactive Bladder (OAB) Symptom Score (OABSS). Severe and moderate lower urinary tract symptoms (LUTS) were defined as IPSS ≥ 20 and ≥ 8, respectively; OAB was defined as a nocturnal frequency of ≥ 2 and a total OABSS of ≥ 3. In total, 203 patients (median age: 66 years) were included, with a mean follow-up of 8.4 years after treatment. The IPSS and OABSS worsened after 3 months of treatment; these scores improved to pretreatment levels after 18-36 months in most patients. Patients with a higher baseline IPSS and OABSS had a higher frequency of moderate and severe LUTS and OAB at 24 and 60 months, respectively. LUTS and OAB at 24 and 60 months were not correlated with the dosimetric factors of LDR-BT. Although the rate of long-term urinary toxicities assessed using IPSS and OABSS was low, the baseline scores were related to long-term function. Refining patient selection may further reduce long-term urinary toxicity.

H&N and Skin (HNS) GEC-ESTRO Working Group critical review of recommendations regarding prescription depth, bolus thickness and maximum dose in skin superficial brachytherapy with flaps and customized moulds

The aim of this publication is the assessment of the existing guidelines for non-melanoma skin cancer (NMSC) superficial brachytherapy (BT) and make a critical review based on the existing literature about the maximum dose prescription depth, bolus thickness and maximum skin surface dose (D_max) of the published clinical practice. A systematic review of NMSC superficial BT published articles was carried out by the GEC-ESTRO Head & Neck and Skin (HNS) Working Group (WG). 10 members and 2 external reviewers compared the published clinical procedures with the recommendations in the current guidelines and examined the grade of evidence. Our review verified that there is a large variation among centres with regards to clinical practice in superficial BT and identified studies where published parameters such as maximum dose prescription depth, bolus thickness and D_max exceed the constraints recommended in the guidelines, while showing excellent results in terms of local control, toxicity and cosmesis. This review confirmed that current recommendations on skin superficial BT do not include published experience on tumours treated with superficial BT that require dose prescription depth beyond the recommended 5mm under the skin surface and that the existing literature does not provide sufficient evidence to relate dosimetry of superficial BT to patient reported outcome measures. The GEC-ESTRO HNS WG considers acceptable to prescribe superficial BT dose at a depth above 5mm beyond the skin surface, and modify the bolus thickness to optimize the treatment plan and adjust the acceptable maximum dose on the skin surface, all pending clinical situation.

Evaluation of dosimetric effects of metallic artifact reduction and tissue assignment on Monte Carlo dose calculations for 125 I prostate implants

PURPOSE

Monte Carlo (MC) simulation studies, aimed at evaluating the magnitude of tissue heterogeneity in ¹²⁵ I prostate permanent seed implant brachytherapy (BT), customarily use clinical post-implant CT images to generate a virtual representation of a realistic patient model (virtual patient model). Metallic artifact reduction (MAR) techniques and tissue assignment schemes (TAS) are implemented on the post-implant CT images to mollify metallic artifacts due to BT seeds and to assign tissue types to the voxels corresponding to the bright seed spots and streaking artifacts, respectively. The objective of this study is to assess the combined influence of MAR and TAS on MC absorbed dose calculations in post-implant CT-based phantoms. The virtual patient models used for ¹²⁵ I prostate implant MC absorbed dose calculations in this study are derived from the CT images of an external radiotherapy prostate patient without BT seeds and prostatic calcifications, thus averting the need to implement MAR and TAS.

METHODS

The geometry of the IsoSeed I25.S17plus source is validated by comparing the MC calculated results of the TG-43 parameters for the line source approximation with the TG-43U1S2 consensus data. Four MC absorbed dose calculations are performed in two virtual patient models using the egs_brachy MC code: (1) TG-43-based D_{w,w-TG 43} , (2) D_w,w-MBDC that accounts for interseed scattering and attenuation (ISA), (3) D_m,m that examines ISA and tissue heterogeneity by scoring absorbed dose in tissue, and (4) D_w,m that unlike D_m,m scores absorbed dose in water. The MC absorbed doses (1) and (2) are simulated in a TG-43 patient phantom derived by assigning the densities of every voxel to 1.00 g cm^-3 (water), whereas MC absorbed doses (3) and (4) are scored in the TG-186 patient phantom generated by mapping the mass density of each voxel to tissue according to a CT calibration curve. The MC absorbed doses calculated in this study are compared with VariSeed v8.0 calculated absorbed doses. To evaluate the dosimetric effect of MAR and TAS, the MC absorbed doses of this work (independent of MAR and TAS) are compared to the MC absorbed doses of different ¹²⁵ I source models from previous studies that were calculated with different MC codes using post-implant CT-based phantoms generated by implementing MAR and TAS on post-implant CT images.

RESULTS

The very good agreement of TG-43 parameters of this study and the published consensus data within 3% validates the geometry of the IsoSeed I25.S17plus source. For the clinical studies, the TG-43-based calculations show a D₉₀ overestimation of more than 4% compared to the more realistic MC methods due to ISA and tissue composition. The results of this work generally show few discrepancies with the post-implant CT-based dosimetry studies with respect to the D₉₀ absorbed dose metric parameter. These discrepancies are mainly Type B uncertainties due to the different ¹²⁵ I source models and MC codes.

CONCLUSIONS

The implementation of MAR and TAS on post-implant CT images have no dosimetric effect on the ¹²⁵ I prostate MC absorbed dose calculation in post-implant CT-based phantoms.

CT-MR Image Fusion for Post-Implant Dosimetry Analysis in Brain Tumor Seed Implantation- a Preliminary Study

Purpose

To calculate and evaluate postimplant dosimetry (PID) with CT-MR fusion technique after brain tumor brachytherapy and compare the result with CT-based PID.

Methods and Materials

16 brain tumor patients received MR-guided intervention with Iodine-125 (¹²⁵I) seed implantation entered this preliminary study for PID evaluation. Registration and fusion of CT and MR images of the same patients were performed one day after operation. Seeds identification and targets delineation were carried out on CT, MR, and CT-MR fusion images, each. The number and location of seeds on MR or CT- MR fusion images were compared with those of actually implanted seeds. Clinical target volume (CTV) and dosimetric parameters such as %D90, %V100 and external V100 were measured and calculated. In addition, the correlation of the fusion to CT CTV ratio and other factors were analyzed.

Results

The numbers of fusion seeds were not significantly different compared with reference seeds (t =1.76, p >0.05). The difference between reference seeds numbers and truly extracted MR seeds numbers was statistically significant (t =3.91, p <0.05). All dosimetric parameters showed significant differences between the two techniques (p <0.05). The mean CTV delineated on fusion images was 34.3 ± 33.6, smaller than that on CT images. The mean values of external V100, %V100 and %D90 on fusion images were larger than those on CT images. Correlation analysis showed that the fusion-CT V100 ratio was positively and significantly correlated with the fusion-CT volume ratio.

Conclusions

This preliminary study indicated that CT-MR fusion-based PID exhibited good accuracy for ¹²⁵I brain tumor brachytherapy dosimetry when compared to CT-based PID and merits further research to establish best-outcome protocols.

Autonomous Prostate Segmentation in 2D B-Mode Ultrasound Images

Prostate brachytherapy is a treatment for prostate cancer; during the planning of the procedure, ultrasound images of the prostate are taken. The prostate must be segmented out in each of the ultrasound images, and to assist with the procedure, an autonomous prostate segmentation algorithm is proposed. The prostate contouring system presented here is based on a novel superpixel algorithm, whereby pixels in the ultrasound image are grouped into superpixel regions that are optimized based on statistical similarity measures, so that the various structures within the ultrasound image can be differentiated. An active shape prostate contour model is developed and then used to delineate the prostate within the image based on the superpixel regions. Before segmentation, this contour model was fit to a series of point-based clinician-segmented prostate contours exported from conventional prostate brachytherapy planning software to develop a statistical model of the shape of the prostate. The algorithm was evaluated on nine sets of in vivo prostate ultrasound images and compared with manually segmented contours from a clinician, where the algorithm had an average volume difference of 4.49 mL or 10.89%.

GEC-ESTRO ACROP prostate brachytherapy guidelines

This is an evidence-based guideline for prostate brachytherapy. Throughout levels of evidence quoted are those from the Oxford Centre for Evidence based Medicine (https://www.cebm.ox.ac.uk/resources/levels-of-evidence/oxford-centre-for-evidence-based-medicine-levels-of-evidence-march-2009). Prostate interstitial brachytherapy using either permanent or temporary implantation is an established and evolving treatment technique for non-metastatic prostate cancer. Permanent brachytherapy uses Low Dose Rate (LDR) sources, most commonly I-125, emitting photon radiation over months. Temporary brachytherapy involves first placing catheters within the prostate and, on confirmation of accurate positioning, temporarily introducing the radioactive source, generally High Dose Rate (HDR) radioactive sources of Ir-192 or less commonly Co-60. Pulsed dose rate (PDR) brachytherapy has also been used for prostate cancer [1] but few centres have adopted this approach. Previous GEC ESTRO recommendations have considered LDR and HDR separately [2-4] but as there is considerable overlap, this paper provides updated guidance for both treatment techniques. Prostate brachytherapy allows safe radiation dose escalation beyond that achieved using external beam radiotherapy alone as it has greater conformity around the prostate, sparing surrounding rectum, bladder, and penile bulb. In addition there are fewer issues with changes in prostate position during treatment delivery. Systematic review and randomised trials using both techniques as boost treatments demonstrate improved PSA control when compared to external beam radiotherapy alone [5-7].

Prostate cancer brachytherapy: SFRO guidelines 2021

Prostate brachytherapy techniques are described, concerning both permanent seed implant and high dose rate brachytherapy. The following guidelines are presented: brachytherapy indications, implant procedure for permanent low dose rate implants and high dose rate with source projector, as well as dose and dose-constraints objectives, immediate postoperative management, post-treatment evaluation, and long-term follow-up.

Best practice in brachytherapy

The 2020 recommendations for good brachytherapy procedures ("Recorad") are updated based on the 2016 article. This new brachytherapy article took into account recent data published in the literature as well as international recommendations. The different brachytherapy steps are successively described from the treatment preparation (brachytherapy technique prescription; procedure and material, dedicated images for planification, dose distribution analysis and validation) to the end of the procedure as well as post-treatment surveillance.

Radioactive Iodine-125 in Tumor Therapy: Advances and Future Directions

Radioactive iodine-125 (I-125) is the most widely used radioactive sealed source for interstitial permanent brachytherapy (BT). BT has the exceptional ability to deliver extremely high doses that external beam radiotherapy (EBRT) could never achieve within treated lesions, with the added benefit that doses drop off rapidly outside the target lesion by minimizing the exposure of uninvolved surrounding normal tissue. Spurred by multiple biological and technological advances, BT application has experienced substantial alteration over the past few decades. The procedure of I-125 radioactive seed implantation evolved from ultrasound guidance to computed tomography guidance. Compellingly, the creative introduction of 3D-printed individual templates, BT treatment planning systems, and artificial intelligence navigator systems remarkably increased the accuracy of I-125 BT and individualized I-125 ablative radiotherapy. Of note, utilizing I-125 to treat carcinoma in hollow cavity organs was enabled by the utility of self-expandable metal stents (SEMSs). Initially, I-125 BT was only used in the treatment of rare tumors. However, an increasing number of clinical trials upheld the efficacy and safety of I-125 BT in almost all tumors. Therefore, this study aims to summarize the recent advances of I-125 BT in cancer therapy, which cover experimental research to clinical investigations, including the development of novel techniques. This review also raises unanswered questions that may prompt future clinical trials and experimental work.

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.

Robot-assisted salvage seminal vesicle excision for isolated recurrence after low-dose-rate prostate brachytherapy

OBJECTIVES

To report clinical and functional outcomes for patients who have undergone salvage robot-assisted seminal vesicle excision (RA-SVE) for the focal treatment of isolated seminal vesical (SV) recurrence after treatment for prostate cancer by low-dose-rate brachytherapy.

PATIENTS AND METHODS

Patients with rising prostate-specific antigen (PSA) after low-dose-rate prostate brachytherapy (LDR-PB) underwent multi-parametric magnetic resonance imaging (mp-MRI) of the prostate and ¹¹ C-Choline or ⁶⁸ Ga-prostate-specific membrane antigen (⁶⁸ Ga-PSMA) positron emission tomography/computed tomography (PET/CT) scan, followed by targeted transperineal biopsy of the prostate and SVs. Isolated SV recurrence were identified in 17 (0.38%) LDR-PB patients. These 17 patients were offered RA-SVE.

RESULTS

The median total operative time was 90 min and blood loss 50 mL with no postoperative transfusions required. The median hospital stay was 1 day. No intra- or postoperative complications were documented. Continence status was unaffected, no patient required urinary pads. Postoperative pathology confirmed SV invasion in all specimens. Surgical margins were positive in seven (41%) patients. All patients had at least one positive imaging study, although three (18%) mp-MRI and five (29%) PET/CT assessments were negative. One (6%) pre-SVE biopsy was also negative but with positive imaging. Salvage SVE failure, defined as three consecutive PSA rises or the need for further treatment, occurred in six patients of whom three had a positive margin. Overall failure-free survival rates were 86%, 67%, and 53% at 1, 2, and 3 years after SVE, respectively.

CONCLUSIONS

Salvage RA-SVE appears to be a safe focal treatment, with very low morbidity, for patients with localised SV recurrence after LDR-PB. It permits deferral of androgen deprivation therapy in selected patients. Bilateral SVE is mandatory. This surgical option should be considered in patients with isolated prostate cancer recurrence to the SV.

Patient assessment of lower urinary tract symptoms using the international prostate symptom score following low-dose-rate prostate brachytherapy

PURPOSE

To correlate changes in urinary patient-reported outcomes including the International Prostate Symptom Score (IPSS), acute urinary retention and urethral stricture with urethral dose in those treated with low dose rate (LDR) prostate brachytherapy.

MATERIALS AND METHODS

Patients treated with prostate LDR between 2012 and 2019 (n=117) completed IPSS urinary symptom assessments prior to treatment and at each follow-up. CT simulation was obtained with urinary catheter 1-month post-implant for dosimetric analysis. 113 patients with pre- and ≥1 post-LDR IPSS score available were analyzed. Urethral dosimetric parameters including U75, U100, U125, U150 and U200 were abstracted from post-implant dosimetry and assessed for association with urinary toxicity using bivariate logistic regression and Spearman correlation. Outcomes included clinically significant change (CSC, defined as 4 or more points or 25% rise above baseline) in IPSS score at 6 and 12 months, acute urinary retention (AUR), and urethral stricture (US).

RESULTS

89 (79%) patients were treated with LDR monotherapy (145 Gy) and 24 (21%) with LDR boost (110 Gy) with external beam radiation therapy. Twenty (18%) had baseline IPSS ≥15. Median IPSS scores were: baseline 6 (3-12; n=113), 1-month 17 (10-25; n=110), 6 months 12 (7-18; n=77), 1 year 8 (5-14; n=52). CSC-6 was observed in 59 (77%), CSC-12 in 26 (50%), AUR in 12 (11%), and US in 4 (4%). No association was identified between urethral dose parameters and CSC-6, CSC-12, AUR, or US. No correlation between urethral dose and IPSS at 6- and 12-months was identified. The IPSS ≥15 group exhibited lower rates of CSC-12 (13% v. 57%, p=0.05) but not CSC-6 (55% v. 80%, p=0.12).

CONCLUSIONS

We did not find a relationship between urethral dose and IPSS elevation, AUR or US. We did identify a significantly lower change in IPSS at 12 months for those with baseline IPSS ≥15 compared to those with low baseline scores.

IVIM Parameters on MRI Could Predict ISUP Risk Groups of Prostate Cancers on Radical Prostatectomy

Purpose

To elucidate the usefulness of intravoxel incoherent motion (IVIM)/apparent diffusion coefficient (ADC) parameters in preoperative risk stratification using International Society of Urological Pathology (ISUP) grades.

Materials and Methods

Forty-five prostate cancer (PCa) patients undergoing radical prostatectomy (RP) after prostate multiparametric magnetic resonance imaging (mpMRI) were included. The ISUP grades were categorized into low-risk (I-II) and high-risk (III-V) groups, and the concordance between the preoperative and postoperative grades was analyzed. The largest region of interest (ROI) of the dominant tumor on each IVIM/ADC image was delineated to obtain its histogram values (i.e., minimum, mean, and kurtosis) of diffusivity (D), pseudodiffusivity (D*), perfusion fraction (PF), and ADC. Multivariable logistic regression analysis of the IVIM/ADC parameters without and with preoperative ISUP grades were performed to identify predictors for the postoperative high-risk group.

Results

Thirty-two (71.1%) of 45 patients had concordant preoperative and postoperative ISUP grades. D_mean, D*_kurtosis, PF_kurtosis, ADC_min, and ADC_mean were significantly associated with the postoperative ISUP risk group (all p < 0.05). D_mean and D*_kurtosis (model I, both p < 0.05) could predict the postoperative ISUP high-risk group with an area under the curve (AUC) of 0.842 and a 95% confidence interval (CI) of 0.726-0.958. The addition of D*_kurtosis to the preoperative ISUP grade (model II) may enhance prediction performance, with an AUC of 0.907 (95% CI 0.822-0.992).

Conclusions

The postoperative ISUP risk group could be predicted by D_mean and D*_kurtosis from mpMRI, especially D*_kurtosis. Obtaining the biexponential IVIM parameters is important for better risk stratification for PCa.

Low-/high-dose-rate brachytherapy boost in patients with intermediate-risk prostate cancer treated with radiotherapy: long-term results from a single institution team experience

Purpose

To compare brachytherapy (BT) boost of low-dose-rate (LDR) and high-dose-rate (HDR) techniques in patients diagnosed with intermediate-risk prostate cancer.

Material and methods

Between January 2005 and February 2018, 142 patients (50 LDR and 92 HDR) with intermediate-risk prostate cancer were treated with a BT boost, and retrospectively analyzed. Prescribed dose was 45 Gy with external beam radiotherapy (EBRT) plus 100-108 Gy with LDR-BT, and 60 Gy with EBRT plus one fraction of 10 Gy with HDR-BT. 99% of patients received androgen deprivation therapy (ADT) for 6 months. Primary endpoint was to compare LDR and HDR boosts in terms of biochemical progression-free survival (bPFS). Secondary endpoint, after re-classifying patients into "favorable" and "unfavorable" sub-groups, was to analyze differences with a similar treatment intensity.

Results

Median overall follow-up for the total cohort was 66.5 months (range, 16-185 months). There were no significant differences in bPFS, overall survival, cause specific survival, local failure, lymph node failure, or distant failure when LDR or HDR was employed. bPFS at 90 months was 100% for favorable, and 89% and 85% for unfavorable patients at 60 months and 90 months, respectively (log-rank test, p = 0.017). The crude incidence of genitourinary acute and chronic toxicity grade 3 was 0.7% and 4%, respectively. Twelve patients (8%) had chronic rectal hemorrhage grade 2, in whom argon was applied (4 LDR and 8 HDR).

Conclusions

Combined treatment is an excellent therapeutic option in patients with intermediate-risk prostate carcinoma, with similar results in both LDR and HDR approaches and very low toxicities. Importantly, the current literature has indicated that unfavorable-risk patients belong to a different category, and should be treated as patients with high-risk factors. Therefore, the stratification and identification of both risk groups is extremely relevant.

Superior Postimplant Dosimetry Achieved Using Dynamic Intraoperative Dosimetry for Permanent Prostate Brachytherapy

PURPOSE

Low-dose-rate brachytherapy is a highly effective treatment modality for prostate carcinoma, but postimplant dosimetry quality is essential and correlated with likelihood of treatment success. Registered ultrasound and fluoroscopy (iRUF) can facilitate real-time intraoperative monitoring and plan adaptation, with the aim of attaining superior dosimetric outcomes. The purpose of this research was to compare clinical postimplant dosimetric results of iRUF-guided brachytherapy against brachytherapy using standard ultrasound-guided intraoperative dosimetry methods.

METHODS AND MATERIALS

We analyzed postimplant dosimetry in 292 patients treated with Pd-103 between January 2007 and December 2018. All patients had postimplant dosimetry measured on day 0 to 1 using fused magnetic resonance/computed tomography assessment. Fifty-two patients were treated in 2 prospective clinical trials using iRUF intraoperative dosimetry, including 6 patients in a pilot study and 46 treated in a phase 2 study. Postimplant dosimetry in iRUF-treated patients was compared with dosimetry from 240 patients treated using standard (real-time ultrasound) intraoperative seed tracking.

RESULTS

For every parameter measuring dose coverage to the prostate, iRUF patients had significantly higher values, irrespective of adjustment for year of treatment. In adjusted analyses, parameters of dose to urethra and rectum were not significantly higher among iRUF-treated patients.

CONCLUSIONS

Use of iRUF intraoperative dosimetry was associated with improved postimplant dose coverage in prostate, without associated increases in doses to urethra or rectum.

The one hundred most cited publications in prostate brachytherapy

PURPOSE

The aim of this study is to identify the leaders in research on prostate brachytherapy through a bibliometric analysis of the top 100 most cited publications in the field.

METHODS AND MATERIALS

A broad search was performed with the term "prostate brachytherapy" using the Web of Science database to generate wide-ranging results that were reviewed by reading the abstracts and, if necessary, the articles to select the top 100 most cited publications.

RESULTS

The median of the total citation count was 187 (range 132-1464). The median citation per year index (citations/year since publication) was 13.5 (range 6.3-379.0). In all publications, the first author was also the corresponding author. The top publishing countries of the first author included the United States (n = 78), Canada (n = 6), the UK (n = 5), and Germany (n = 4). The journal with the most publications was the International Journal of Radiation Oncology Biology Physics (n = 38). There were 27 more publications on low-dose-rate (LDR) than on high-dose-rate (HDR) (43 vs 16) among the top 100. HDR publications had only one first author that had three articles in comparison to LDR publications, which had four first authors, each with three articles on LDR. The United States was the leading country in 43.8% of HDR publications (n = 7) and 88.4% of LDR publications (n = 38).

CONCLUSIONS

Our bibliometric analysis of the top 100 most cited publications clearly demonstrates the North American dominance in the publications of prostate brachytherapy, especially in LDR. However, European first authors were more frequent in HDR publications.

Focal low-dose-rate prostate brachytherapy for low- and intermediate-risk prostate cancer

Purpose

To prospectively investigate the efficacy and feasibility of focal low-dose-rate (LDR) prostate brachytherapy for low- and intermediate-risk prostate cancer.

Material and methods

Between October 2014 and May 2019, nineteen low- and intermediate-risk prostate cancer patients who presented with abnormality on both diffusion-weighted and T2-weighted magnetic resonance imaging (MRI) underwent focal LDR brachytherapy at our institution. Focal gross tumor volume (F-GTV) was delineated on transrectal ultrasound, based on abnormality seen on fused T2-weighted MRI. F-GTV was expanded by 5 mm, as a safety margin, to create focal clinical target volume (F-CTV). Prescribed dose to F-CTV was 145 Gy. Biochemical recurrence (BCR) was determined using Phoenix criterion (prostate specific antigen nadir + 2 ng/ml). Pre- and post-implant dosimetry data were compared using non-parametric Wilcoxon’s rank sum test. Treatment-related toxicities were evaluated using common terminology criteria for adverse events.

Results

Mean F-CTV D_90% was significantly lower in the post-implant evaluation than in intraoperative planning (p = 0.004). On post-implant dosimetry, the mean D_90% for F-GTV and mean V_100% for the entire prostate were 222 Gy and 35%, respectively. Median follow-up time for all patients was 31 months. BCR occurred in one patient after 23 months. Kaplan-Meier 2-year BCR-free rate was 92.9% (95% confidence interval [CI]: 79.4-100%). No patients had grade 1 or greater gastrointestinal toxicity. Three patients who were taking α-blockers to treat benign prostatic hyperplasia (present before brachytherapy), experienced no treatment-related genitourinary toxicities. Two patients suffered from temporary grade 2 urinary frequency. None of the remaining patients experienced grade 2 or higher genitourinary toxicity.

Conclusions

Focal LDR prostate brachytherapy appears acceptable for MRI-based index tumors, with a low cumulative incidence of BCR. Such brachytherapy might offer a feasible minimally invasive therapeutic option for localized prostate cancer.

Focal Brachytherapy for Localized Prostate Cancer: Midterm Outcomes

PURPOSE

Focal brachytherapy (F-BT) is a suitable technique for focal therapy in localized prostate cancer. It has the ability to adapt the seed implantation to the volume and location of the tumor. The aim of this study was to assess F-BT oncologic, functional, and toxicity midterm outcomes in men who underwent prostate cancer treatment.

METHODS AND MATERIALS

The study included 39 men with low- to intermediate-risk prostate cancer treated with F-BT between 2010 and 2015. The dose prescription was 145 Gy. Failure was defined as the presence of any residual prostate cancer in the treated area. The primary and secondary endpoints were the F-BT oncologic and functional outcomes, respectively. A 2-sided P value < .05 indicated statistical significance.

RESULTS

The mean follow-up time was 65 months (range, 43-104 months). After 24 months, 34 patients underwent control biopsies and 5 patients refused. The biopsies were negative in 27 cases (79%) and positive in 7 cases (21%), all outside the volume treated. Biochemical relapse-free survival at 5 years, disease-free survival, and overall survival were 96.8% ± 0.032%, 79.5% ± 0.076%, and 100%, respectively. The mean International Prostate Symptom Score at 2 months was significantly higher than initially (P = .0003), with no significant difference later. No late urinary, sexual, or rectal toxicity was observed. Salvage treatment was possible with good tolerance at 3.4 years of follow-up. Limitations of this study include the retrospective nature and lack of randomization.

CONCLUSIONS

F-BT is a safe and effective treatment for selected patients presenting with low- or intermediate-risk localized prostate cancer.

A comparison of treatment planning techniques for low-dose-rate (LDR) prostate brachytherapy

PURPOSE

The purpose of this study was to compare low-dose-rate prostate brachytherapy treatment plans created using three retrospectively applied planning techniques with plans delivered to patients.

METHODS AND MATERIALS

Treatment plans were created retrospectively on transrectal ultrasound (TRUS) scans for 26 patients. The technique dubbed 4D Brachytherapy was applied, using TRUS and MRI to obtain prostatic measurements required for the associated webBXT online nomogram. Using a patient's MRI scan to create a treatment plan involving loose seeds was also explored. Plans delivered to patients were made using an intraoperative loose seed TRUS-based planning technique. Prostate V₁₀₀ (%), prostate V₁₅₀ (%), prostate D₉₀ (Gy), rectum D_0.1cc (Gy), rectum D_2cc (Gy), urethra D₁₀ (%), urethra D₃₀ (%), and prostate volumes were measured for each patient. Statistical analysis was used to assess and compare plans.

RESULTS

Prostate volumes measured by TRUS and MRI were significantly different. Prostate volumes calculated by the webBXT online nomogram using TRUS- and MRI-based measurements were not significantly different. Compared with delivered plans, TRUS-based 4D Brachytherapy plans showed significantly lower rectum D_0.1cc (Gy) values, MRI-based 4D Brachytherapy plans showed significantly higher prostate V₁₀₀ (%) values and significantly lower rectum D_0.1cc (Gy), urethra D₁₀ (%), and urethra D₃₀ (%) values, and loose seed MRI-based plans showed significantly lower prostate V₁₀₀ (%), prostate D₉₀ (Gy), rectum D_0.1cc (Gy), rectum D_2cc (Gy), urethra D₁₀ (%), and urethra D₃₀ (%) values.

CONCLUSIONS

TRUS-based 4D Brachytherapy plans showed similar dosimetry to delivered plans; rectal dosimetry was superior. MRI can be integrated into the 4D Brachytherapy workflow. The webBXT online nomogram overestimates the required number of seeds.

Relapse patterns after low-dose-rate prostate brachytherapy

PURPOSE

When biochemical failure (BF) develops after low-dose-rate prostate brachytherapy, the relapse site is frequently not found. We set out to find whether prostate-specific membrane antigen positron emission tomography -CT (PSMA PET-CT) scanning has improved knowledge of relapse patterns.

METHODS AND MATERIALS

A database was analyzed, which contained information and long-term followup on 903 men who had an iodine-125 seed implant as monotherapy for early-stage prostate cancer. There was a total of 68 BFs.

RESULT

In 38 men developing BF before PSMA PET-CT scanning was available, the site of relapse was local in six, distant in twelve, and unknown in twenty. In 30 men developing BF more recently who had a PSMA PET-CT scan, the relapse site was demonstrated in all cases, and 19 (63%) men had relapsed at the prostate base. Radiation dosimetry of base relapses and paired controls demonstrated that implants routinely delivered a lower radiation dose to the base than to the rest of the prostate. Eight of seventeen cases found to have prostate relapse only underwent salvage prostatectomy.

CONCLUSION

PSMA PET-CT scanning is highly effective in demonstrating the relapse site(s) when BF develops after low-dose-rate prostate brachytherapy. Knowledge of the relapse site increases management options for men developing BF.

Salvage I-125 brachytherapy for locally-recurrent prostate cancer after radiotherapy

Purpose

Retrospective, single-institution analysis of clinical outcomes and treatment-related toxicity in patients treated with salvage I-125 low-dose rate (LDR) brachytherapy (BT) for locally-recurrent prostate cancer after radiotherapy.

Materials and methods

Between 2008 and 2018, 30 patients with biopsy-confirmed prostate cancer recurrence underwent salvage treatment with I-125 LDR-BT. Of these 30 patients, 14 were previously treated with primary external beam radiotherapy (EBRT; median dose, 73 Gy) and 16 with primary I-125 LDR-BT (145 Gy and 160 Gy in 14 and 2 cases, respectively). At seed implantation, the mean age was 75.8 years, with a median Gleason score of 7 and pre-salvage PSA of <10 ng/mL. Six patients received androgen deprivation therapy for six months after relapse diagnosis. The prescribed salvage I-125 BT dose to the gland was 120-130 Gy, with dose restrictions of Dmax <135% (urethra) and <100% (rectum). Toxicity was evaluated according to the CTCAE scale (v4.0).

Results

At a median follow-up of 45 months, the biochemical recurrence-free survival rates at 1, 3 and 5 years were 86.7%, 56.7% and 53.3%, respectively. Overall survival at 5 years was 87%. On the multivariate analysis, two variables were significant predictors of recurrence: PSA at relapse and nadir PSA post-salvage. Grade 3 genitourinary toxicity was observed in 5 patients (radiation-induced cystitis in 3 cases and urethral stenosis in 2) and G3 gastrointestinal toxicity in 3 patients (rectal bleeding).

Conclusion

Salvage therapy with I-125 brachytherapy is a safe and effective treatment option for locally-recurrent prostate cancer in previously-irradiated patients. High pre-salvage PSA and post-salvage nadir PSA values were significantly associated with a worse disease control after salvage I-125 LDR-BT. In well-selected patients, I-125 LDR-BT is comparable to other salvage therapies in terms of disease control and toxicity. However, more research is needed to determine the optimal management of locally-recurrent prostate cancer.

Brachytherapy in Belgium in 2018. A national survey of the brachytherapy study group of the Belgian SocieTy for Radiotherapy and Oncology (BeSTRO)

PURPOSE

To explore the current practices patterns and evaluate the actual brachytherapy (BT) resources in Belgium.

MATERIAL AND METHODS

In 2019, the Brachytherapy Study Group proposed to conduct a survey on behalf of the Belgian SocieTy of Radiation Oncology (BeSTRO) in order to identify current BT practice patterns. An electronic questionnaire was sent to all primary radiotherapy centers in Belgium. This questionnaire was based on the questionnaire that was used by the Italian Association of Radiation Oncology (AIRO) in 2016, asking for: (a) General information on the Radiation Oncology Centre; (b) BT equipment and human resources; (c) BT procedures; (d) BT assessment (number of patients treated annually, treated sites, and different modalities of treatments).

RESULTS

All 24 radiation oncology centers (100% response rate) answered the questionnaire and gave also information on the performance of brachytherapy in their (eventual) satellite centers. Eighteen (18) BT afterloader units were installed and operational in 2018. Thirteen centers mentioned a prostate seed implant program, one center a prostate and eye plaque program and one center only an eye plaque program. Less than 50% of centers have the infrastructure to offer the full-range of BT in their own department. In 2018, 1486 patients received a BT-treatment, 28% of them were treated by prostate seed implant, 8% were treated by eye-(seed) BT and 64% by high dose rate (HDR)/pulsed dose rate (PDR) BT. Forty-five percent of HDR/PDR patients were treated by vaginal dome BT, 22% by intra-uterine BT, 11% by skin BT, 10% by breast BT (almost exclusively in one centre), 8% for benign pathology (keloid) and the remaining 4% were treated for prostate (as a boost or as salvage in one centre), anal, penile, lung or oesophageal cancer.

CONCLUSIONS

Belgian radiotherapy departments often perform BT only in a (highly) selected group of pathologies, resulting in a limited number of patients treated by this technique despite the sufficient availability of BT equipment. Modern indications are often not covered, hence patients do not have regular access to recognized treatment options, possibly leading to inferior oncological outcome. BeSTRO will use the results of this survey to stimulate improvements in training, awareness, education, implementation, collaboration and cooperation in the field of brachytherapy.

Impact of real-time, dose-escalated permanent seed implant brachytherapy in intermediate-risk prostate cancer

Purpose

To retrospectively evaluate biochemical control and toxicity in patients who underwent 125I seed brachytherapy (BT) for intermediate-risk prostate cancer (PCa).

Materials and Methods

Between January 2004-December 2014, 395 patients with intermediate-risk PCa underwent 125I BT. Of these, 117 underwent preoperative planning (PP; 145 Gy) and 278 real-time intraoperative preplanning (IoP; 160 Gy). All patients were followed for ≥ 6 months (> 5 years in 48% of patients and > 7 years in 13%). Median follow-up was 59 months.

Results

Biochemical relapse-free survival (BRFS) rates at 5 and 8 years were, respectively, 91.7% and 82.1%. By treatment group, the corresponding BRFS rates were 93.5% and 90% for IoP and 89% and 76.8% for PP. The maximum dose to the urethra remained unchanged (217 Gy) despite the dose escalation (from 145 to 160 Gy), without any significant increase in treatment-related toxicity (p = 0.13). Overall toxicity outcomes in the series were excellent, with only 3 cases (0.76%) of grade 3 genitourinary toxicity.

Conclusion

The real-time intraoperative planning technique at 160 Gy yields better biochemical controls than the preoperative planning technique at 145 Gy. Dose escalation did not increase urinary toxicity. The excellent results obtained with the IoP BT technique support its use as the first treatment option in this patient population.

A Population-based Statistical Model for Investigating Heterogeneous Intraprostatic Sensitivity to Radiation Toxicity After 125I Seed Implantation

AIM

To develop a population-based statistical model in order to find a spatial pattern of dose distribution which is related to lower urinary tract symptoms (LUTS) after iodine-125 (¹²⁵I) seed implantation for prostate cancer.

PATIENTS AND METHODS

A total of 75 patients underwent ¹²⁵I seed implantation for prostate cancer. Principal component analysis was applied to the standardized dose array and for each patient dose distribution was uniquely characterized by a combination of weighted eigenvectors. The correlation between eigenvectors and the severity of LUTS was investigated with linear regression analysis.

RESULTS

Eight eigenvectors were identified as being significantly associated with the severity of LUTS (p<0.05). Multivariate regression model identified that intraprostatic parameters, which were positively associated with the severity of LUTS, were distributed around a portion of the urethral base and a peripheral region of the prostate.

CONCLUSION

We established a population-based statistical model that may indicate a significant dose pattern associated with the severity of radiation toxicity.

A history of transurethral resection of the prostate should not be a contra-indication for low-dose-rate 125I prostate brachytherapy: results of a prospective Uro-GEC phase-II trial

Purpose

Early reports suggested that transurethral resection (TURP) prior to permanent seed brachytherapy (BT) results in high incontinence rates. Guidelines consider prior TURP as a contra-indication to treatment, but improvements in imaging and treatment planning may reduce this risk, and are investigated in this prospective study.

Material and methods

99 men with histologically proven low- to intermediate-risk, localized prostate cancer, with a history of TURP performed at least 3 months before BT procedure were enrolled. All patients received a permanent seed implant between March 2009 and June 2015. Intra-operative interactive planning was recommended to ensure optimal accuracy of seed placement during the procedure. No supplemental external beam was allowed. Target and organ at risk contouring, definition of clinical target volume (CTV), and dosimetric parameters followed the modified GEC-ESTRO guidelines for permanent seed implants, as described an earlier report of our group. Follow-up was scheduled every 3 months for the first year, and every 6 months afterwards, with minimum follow-up of 2 years.

Study endpoints

The primary endpoint was the incidence of post-implant urinary incontinence. Secondary endpoints were the incidence of urinary and gastro-intestinal toxicity, the eventual impact on the sexual function, and the freedom from biochemical failure.

Results

The median follow-up time for these 99 patients was 49 months (min. 24, max. 96). In this series, the incontinence rate was 2% after TURP + BT and 2% in case of TURP + BT + re-TURP, ending up with a total urinary incontinence rate of 4%. Acute and late urinary toxicities were extremely low. No significant late gastro-intestinal toxicity was seen, and the 5-year biochemical non-evidence of disease (bNED) was 93%.

Conclusions

The excellent long-term results and low morbidity presented as well as many advantages of prostate brachytherapy over other treatments demonstrates that brachytherapy is an effective treatment for patients with transurethral resection and organ-confined prostate cancer.

Long-term oncological and functional follow-up in low-dose-rate brachytherapy for prostate cancer: results from the prospective nationwide Swiss registry

OBJECTIVE

To evaluate the long-term oncological, functional and toxicity outcomes of low-dose-rate brachytherapy (LDR-BT) in relation to risk factors and radiation dose in a prospective multicentre cohort.

PATIENTS AND METHODS

Data of patients from 12 Swiss centres undergoing LDR-BT from September 2004 to March 2018 were prospectively collected. Patients with a follow-up of ≥3 months were analysed. Functional and oncological outcomes were assessed at ~6 weeks, 6 and 12 months after implantation and annually thereafter. LDR-BT was performed with ¹²⁵ I seeds. Dosimetry was done 6 weeks after implantation based on the European Society for Radiotherapy and Oncology recommendations. The Kaplan-Meier method was used for biochemical recurrence-free survival (BRFS). A prostate-specific antigen (PSA) rise above the PSA nadir + 2 was defined as biochemical failure. Functional outcomes were assessed by urodynamic measurement parameters and questionnaires.

RESULTS

Of 1580 patients in the database, 1291 (81.7%) were evaluable for therapy outcome. The median (range) follow-up was 37.1 (3.0-141.6) months. Better BRFS was found for Gleason score ≤3+4 (P = 0.03, log-rank test) and initial PSA level of <10 ng/mL (P < 0.001). D'Amico Risk groups were significantly associated with BRFS (P < 0.001), with a hazard ratio of 2.38 for intermediate- and high-risk patients vs low-risk patients. The radiation dose covering 90% of the prostate volume (D90) after 6 weeks was significantly lower in patients with recurrence. Functional outcomes returned close to baseline levels after 2-3 years. A major limitation of these findings is a substantial loss to follow-up.

CONCLUSION

Our results are in line with other studies showing that LDR-BT is associated with good oncological outcomes together with good functional results.

Safety and efficacy of CT-guided radioactive iodine-125 seed implantation assisted by a 3D printing template for the treatment of thoracic malignancies

OBJECTIVE

To ascertain the safety and efficacy of radioactive iodine-125 seed implantation (RISI) for the treatment of thoracic tumors.

METHODS

Clinical patients with primary or metastatic tumors in the chest treated with RISI were analyzed. The RISI process included the following stages: preoperative planning, template design and 3D printing, CT-guided RISI assisted by a template, and postoperative dosimetric verification. The prescribed dose was ≥ 80 Gy. The main analytic measures were the local control (LC) rate and toxicity.

RESULTS

From April 2015 to July 2018, a total of 92 patients, including 41 with lung cancer and 51 with lung metastases, were analyzed. The median lesion diameter was 5 cm. The median postoperative D90 was 142.6 Gy. The median follow-up was 10.7 months. The overall survival rates at 1 year and 3 years were 59.7% and 22.2%, respectively. The LC rates at 1 year and 3 years were 64.9% and 32.8%, respectively. The LC rates at 3 years for patients with D90 < 140 Gy and D90 > 140 Gy were 23.1% and 54.3%, respectively (P = 0.014). The LC rate of metastatic lung cancer was more favorable than that of primary lung cancer. The multivariate analyses showed that the dose and lesion type were independent factors for LC (P < 0.05). No factors were related to OS. The incidence of pneumothorax and hemoptysis was 35.8% and 3.2%, respectively. Few cases of radiotherapy-related toxicity effects were observed.

CONCLUSIONS

RISI may be safe and efficacious and is associated with few complications during the treatment of thoracic tumors. If patients need local treatment and surgery or radiotherapy is not available, RISI could be considered.

Radiation-related Adverse Effects of CT-guided Implantation of 125I Seeds for Thoracic Recurrent and/or Metastatic Malignancy

During radioactive Iodine-125 seed implantation (RISI), Iodine-125 radionuclide is implanted directly into a lesion and kills tumor cells by steadily emitting radiation. In our study, we analyzed the adverse effects of RISI for thoracic malignancy, and investigated the safety, dosage, and adverse effects of RISI for these cases. Between June 2007 and January 2018, 77 patients with thoracic recurrent and/or metastatic tumors who underwent CT-guided RISI were enrolled. Radiation-related adverse effects were analyzed, including pneumonia, esophagitis, hemorrhage, fistula, skin injury, heart injury, and spinal cord injury. We used the Common Terminology Criteria for Adverse Events (CTCAE) v4.03 to evaluate adverse effects and analyzed the relationship between adverse effects and dosimetric parameters of organs at risk (OAR), including D0.1cc, D2cc, Dmean, and V20. The results of the study were as follows: The median follow-up period was 11 months. The median postoperative dose (D90) was 122 Gy (45.7–241.8 Gy). Three patients (3.9%) showed radiation pneumonitis of grade ≥2. Two patients (2.6%) showed radiation-induced esophagitis of grade ≥2. One patient (1.3%) showed an esophageal fistula. Two patients (2.6%) had a tracheal fistula. Five patients (6.5%) had radiation-related skin reactions. One patient (1.3%) reported chest wall pain, while three (3.9%) showed hemoptysis. No patients showed radiation myelitis or cardiotoxicity. The mean D2cc of organs at risk were 165.7 Gy (lung), 10.61 Gy (esophagus), 10.25 Gy (trachea), 18.07 Gy (blood vessel), 12.64 Gy (heart), 14.77 Gy (spinal cord), 17.47 Gy (skin). Dosimetric parameters, such as D0.1cc, D2cc and Dmean, were higher in patients with toxic reactions (above the upper limit of 95% confidence interval among the overall data). Chi-square test showed that skin D0.1cc > 600 Gy, D2cc > 500 Gy, and Dmean >90 Gy were associated with grade ≥2 radiation dermatitis (p < 0.05), but no clear dose-toxicity correlation was found in other OARs. So, we concluded that the overall incidence of toxicity and adverse effects from RISI for the treatment of thoracic tumors is low. The dose-toxicity characteristics have not been fully defined. Doses within the upper limit of the 95% confidence interval may be considered safe. This was a retrospective analysis, and follow-up period was minimal, indicating possible limitations of this study.

Brachytherapy for the urologist: A multidisciplinary team update for 2019

Brachytherapy is a well-established treatment for localised prostate cancer. Urologists are often tasked with discussing all available treatment options with the newly diagnosed patient. Unlike radical prostatectomy and external beam radiotherapy, knowledge of brachytherapy may be limited. The aim of this article is to provide an up-to-date guide on patient selection, modern brachytherapy techniques and the management of side effects, such that the core urologist can be more confident in both discussing initial treatment options and the long-term management of brachytherapy patients.

Level of Evidence: Level 5 - review article

Accurate and robust deep learning-based segmentation of the prostate clinical target volume in ultrasound images

The goal of this work was to develop a method for accurate and robust automatic segmentation of the prostate clinical target volume in transrectal ultrasound (TRUS) images for brachytherapy. These images can be difficult to segment because of weak or insufficient landmarks or strong artifacts. We devise a method, based on convolutional neural networks (CNNs), that produces accurate segmentations on easy and difficult images alike. We propose two strategies to achieve improved segmentation accuracy on difficult images. First, for CNN training we adopt an adaptive sampling strategy, whereby the training process is encouraged to pay more attention to images that are difficult to segment. Secondly, we train a CNN ensemble and use the disagreement among this ensemble to identify uncertain segmentations and to estimate a segmentation uncertainty map. We improve uncertain segmentations by utilizing the prior shape information in the form of a statistical shape model. Our method achieves Hausdorff distance of 2.7 ± 2.3 mm and Dice score of 93.9 ± 3.5%. Comparisons with several competing methods show that our method achieves significantly better results and reduces the likelihood of committing large segmentation errors. Furthermore, our experiments show that our approach to estimating segmentation uncertainty is better than or on par with recent methods for estimation of prediction uncertainty in deep learning models. Our study demonstrates that estimation of model uncertainty and use of prior shape information can significantly improve the performance of CNN-based medical image segmentation methods, especially on difficult images.

GEC-ESTRO ACROP recommendations on calibration and traceability of LE-LDR photon-emitting brachytherapy sources at the hospital level

Prostate brachytherapy treatment using permanent implantation of low-energy (LE) low-dose rate (LDR) sources is successfully and widely applied in Europe. In addition, seeds are used in other tumour sites, such as ophthalmic tumours, implanted temporarily. The calibration issues for LE-LDR photon emitting sources are specific and different from other sources used in brachytherapy. In this report, the BRAPHYQS (BRAchytherapy PHYsics Quality assurance System) working group of GEC-ESTRO, has developed the present recommendations to assure harmonized and high-quality seed calibration in European clinics. There are practical aspects for which a clarification/procedure is needed, including aspects not specifically accounted for in currently existing AAPM and ESTRO societal recommendations. The aim of this report has been to provide a European wide standard in LE-LDR source calibration at end-user level, in order to keep brachytherapy treatments with high safety and quality levels. The recommendations herein reflect the guidance to the ESTRO brachytherapy users and describe the procedures in a clinic or hospital to ensure the correct calibration of LE-LDR seeds.

The role of radiotherapy in localised and locally advanced prostate cancer

For a patient suffering from non-metastatic prostate cancer, the individualized recommendation of radiotherapy has to be the fruit of a multidisciplinary approach in the context of a Tumor Board, to be explained carefully to the patient to obtain his informed consent. External beam radiotherapy is now delivered by intensity modulated radiotherapy, considered as the gold standard. From a radiotherapy perspective, low-risk localized prostate cancer is treated by image guided intensity modulated radiotherapy, or brachytherapy if patients meet the required eligibility criteria. Intermediate-risk patients may benefit from intensity modulated radiotherapy combined with 4–6 months of androgen deprivation therapy; intensity modulated radiotherapy alone or combined with brachytherapy can be offered to patients unsuitable for androgen deprivation therapy due to co-morbidities or unwilling to accept it to preserve their sexual health. High-risk prostate cancer, i.e. high-risk localized and locally advanced prostate cancer, requires intensity modulated radiotherapy with long-term (≥2 years) androgen deprivation therapy with luteinizing hormone releasing hormone agonists. Post-operative irradiation, either immediate or early deferred, is proposed to patients classified as pT3pN0, based on surgical margins, prostate-specific antigen values and quality of life. Whatever the techniques and their degree of sophistication, quality assurance plays a major role in the management of radiotherapy, requiring the involvement of physicians, physicists, dosimetrists, radiation technologists and computer scientists. The patients must be informed about the potential morbidity of radiotherapy and androgen deprivation therapy and followed regularly during and after treatment for tertiary prevention and evaluation. A close cooperation is needed with general practitioners and specialists to prevent and mitigate side effects and maintain quality of life.

Correlation between real-time intraoperative and postoperative dosimetry and its implications on intraoperative planning

PURPOSE

The purpose of this study was to study the correlation between intraoperative and postimplant dosimetry. We investigated the correlation between prostate (V₁₅₀) and urethra (D₃₀, D₅) dose limits, and whether it is possible to increase prostate D₉₀ and V₁₀₀ in intraoperative planning without violating postimplant urethra and rectum dose limits.

METHODS AND MATERIALS

Seventy-nine patients who underwent real-time ultrasound-guided prostate implants using intraoperative planning from 2013 to 2017 were analyzed. Forty-one of the 79 implants were ¹²⁵I as monotherapy and the remainder was ¹⁰³Pd as boost to external beam radiation therapy or external beam radiation therapy plus androgen deprivation therapy. Prescriptions followed the guidelines of AAPM TG-137. The urethra was catheterized during intraoperative implantation and postimplant imaging to facilitate the urethra identification. T2-cubed MRI and CT were acquired on the same day and about 1 month after the low-dose-rate procedure, and MRI was later fused with the CT scan for accurate delineation of the prostate and postimplant dosimetry evaluation. An institutionally based peer-review process and document procedure were established based on national recommendations. Correlation of dose parameters: D₉₀, V₁₅₀, V₁₀₀ of prostate, D₃₀, D₅ of urethra, and V₁₀₀ of rectum between intraoperative and postimplant plans were evaluated.

RESULTS

D₉₀ and V₁₀₀ declined for all implants between intraoperative and postimplant dosimetry. On average, D₉₀ declined by 17.5% and 21.7% for ¹²⁵I and ¹⁰³Pb implants, respectively. V₁₀₀ declined for all implants between intraoperative and postimplant dosimetry but less pronounced. Prostate V₁₅₀ and urethra D₃₀ and D₅ also showed different tendency of decline. Of the 79 implants, 60 did not meet the postimplant dosimetry target for prostate (V₁₅₀ ≤ 50%), and 46 of the 60 implants met the optimal dosimetry targets for both D₃₀ (<125%) and D₅ (<150%), and the other 14 of the 60 implants failed to meet either the D₃₀ or the D₅ limits. All the implants met the postimplant target dose for rectum: V₁₀₀≤ 1.3 cc.

CONCLUSION

Intraoperative implant dosimetry could not accurately predict postimplant dosimetry; however, to avoid underdosage of prostate, intraoperative D₉₀ should be close to 120% of prescribed dose and V₁₀₀ needs to be close to 100% of prescribed dose. Prostate V₁₅₀> 50% does not necessarily indicate the violation of urethra D₃₀ and D₅ dose limits. For most of the implants, target intraoperative D₉₀ and V₁₀₀ could be raised without violating urethra D₃₀ and D₅ limits recommended by American Brachytherapy Society in postimplant evaluation.

Institutional patient accrual volume and the treatment quality of I‑125 prostate seed implantation in a Japanese nationwide prospective cohort study

PURPOSE

It is unclear whether experience at high-volume institute improves the treatment quality of prostate seed implantation. The aim of this study was to evaluate the effect of institutional experience on postimplant dosimetric parameters in a nationwide prospective cohort study.

METHODS

From July 2005 to June 2007, 2354 patients were registered in the Japanese Prostate Cancer Outcome Study of Permanent I‑125 Seed Implantation (J-POPS), and 1126 patients treated with seed implantation alone were evaluated. As a surrogate for institutional experience, we classified the J‑POPS institutions as high-volume (patient accrual volume was ≥120 patients per institution) or low-volume institutions (patient accrual volume was <120 patients per institution). To compare treatment quality between institutions, we evaluated the postimplant dosimetric parameters including D90, V100/150 (prostatic dose parameters), UD5/90, U200 (urethral dose parameters), and rectum R100/150 (rectal dose parameters).

RESULTS

In the 5 high-volume institutions (n = 601 patients), most of the patients were treated with >144 Gy of D90, whereas in the 20 low-volume institutions (n = 525) some of the patients were treated with <144 Gy. The V100 of most of the high-volume institution patients were >90%, whereas in the low-volume institutions a considerable percentage of patients showed lower V100. Although there was no correlation between D90 and rectal dose parameters, UD90 had a moderate positive correlation with D90 in both the high- and low-volume institutions. U200 varied more widely in the low-volume institutions.

CONCLUSIONS

Our findings indicate that the institutional patient accrual volume is associated with the treatment quality of I‑125 prostate seed implantation.

ESTRO ACROP consensus guideline on CT- and MRI-based target volume delineation for primary radiation therapy of localized prostate cancer

BACKGROUND AND PURPOSE

Delineation of clinical target volumes (CTVs) remains a weak link in radiation therapy (RT), and large inter-observer variation is seen. Guidelines for target and organs at risk delineation for prostate cancer in the primary setting are scarce. The aim was to develop a delineation guideline obtained by consensus between a broad European group of radiation oncologists.

MATERIAL AND METHODS

An ESTRO contouring consensus panel consisting of leading radiation oncologists and one radiologist with known subspecialty expertise in prostate cancer was asked to delineate the prostate, seminal vesicles and rectum on co-registered CT and MRI scans. After evaluation of the different contours, literature review and multiple informal discussions by electronic mail a CTV definition was defined and a guide for contouring the CTV of the prostate and the rectum was developed.

RESULTS

The panel achieved consensus CTV contouring definitions to be used as guideline for primary RT of localized prostate cancer.

CONCLUSION

The ESTRO consensus on CT/MRI based CTV delineation for primary RT of localized prostate cancer, endorsed by a broad base of the radiation oncology community, is presented to improve consistency and reliability.

Low-dose-rate brachytherapy as a minimally invasive curative treatment for localised prostate cancer has excellent oncological and functional outcomes: a retrospective analysis from a single centre

Introduction

Low-dose-rate (LDR) brachytherapy is a widely used therapeutic option for localised prostate cancer. The aim of this study was to analyse the oncological and functional outcomes after 10 years of experience with brachytherapy for localised prostate cancer.

Material and methods

All patients who underwent brachytherapy between April 2006 and September 2017 were included for analysis. Initial prostate-specific antigen (PSA) levels, tumour stages, Gleason scores, positive biopsies, prostate volumes, dosimetric parameters, and urinary symptoms were noted.

Results

A total of 201 patients underwent brachytherapy between April 2006 and September 2017. Of these patients, 159 had >3 years of oncological and functional follow-up. Only these relevant patients were included in the statistical analysis. This showed a significant, persistent decline in PSA levels (p <0.0001): the mean PSA was 1.2 ng/ml after 6 months, 1.1 ng/ml after 1 year, and 0.49 ng/ml after 3 years. Only 9 patients had tumour recurrence (3 patients with Gleason score 6 and 6 patients with Gleason score 7). After receiving adequate treatment, the patients underwent oncological follow-up.

Important obstructive and irritative complaints were most pronounced during the first 9 months and decreased strongly after 18 months of follow-up.

Conclusions

LDR brachytherapy has excellent oncological outcomes with limited functional inconveniences that are adequately treatable. Our 10 years' experience shows that brachytherapy is a safe and effective method for the treatment of low-risk localised prostate cancer.

Permanent seed implant brachytherapy in low-risk prostate cancer: Preoperative planning with 145 Gy versus real-time intraoperative planning with 160 Gy

Aim

The present retrospective study was to compare toxicity and survival outcomes in a group of low-risk PCa patients treated with either the preoperative planning technique (145 Gy) or the real-time IoP technique (160 Gy).

Background

The two most common permanent seed implantation techniques are preoperative planning (PP) with 145 Gy and real-time intraoperative planning (IoP) with 160 Gy. Although IoP has largely replaced PP at many centres in recent years, few studies have directly compared these two techniques.

Materials and methods

Retrospective study of 408 patients with low-risk PCa treated with permanent seed implant brachytherapy at our institution between October 2003 and December 2014. Of these, 187 patients were treated with PP at a dose of 145 Gy while 221 received real-time IoP with 160 Gy.

Results

At a median follow up of 90 months, 5- and 8-year rates of biochemical relapse-free survival (BRFS) were 94.8% and 86% with the IoP technique versus 90.8% and 83.9%, respectively, with PP. The maximum dose to the urethra was <217 Gy with both techniques. Despite the higher dose, IoP did not cause any significant increase in toxicity (p = 0.11).

Conclusions

The present study shows that real-time intraoperative brachytherapy at a dose of 160 Gy yield better biochemical control than preoperative planning at 145 Gy. In addition, urinary toxicity did not increase, despite the dose escalation, probably because the dose constraints to the urethra were met despite the increased dose escalation. These findings support the use of real-time IoP.

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.

UK & Ireland Prostate Brachytherapy Practice Survey 2014-2016

Purpose

To document the current prostate brachytherapy practice across the UK and Ireland and compare with previously published audit results.

Material and methods

Participants from 25 centers attending the annual UK & Ireland Prostate Brachytherapy Conference were invited to complete an online survey. Sixty-three questions assessed the center’s experience and staffing, clinician’s experience, clinical selection criteria and scheduling, number of cases per modality in the preceding three years, low-dose-rate (LDR) pre- and post-implant technique and high-dose-rate (HDR) implant technique. Responses were collated, and descriptive statistical analysis performed.

Results

Eighteen (72%) centers responded with 17 performing LDR only, 1 performing HDR only, and 6 performing both LDR and HDR. Seventy-one percent of centers have > 10 years of LDR brachytherapy experience, whereas 71% centers that perform HDR brachytherapy have > 5 years of experience. Thirteen centers have 2 or more clinicians performing brachytherapy with 61% of lead consultants performing > 25 cases (LDR + HDR) in 2016. The number of implants (range), that includes LDR and HDR, performed by individual practitioners in 2016 was > 50 by 21%, 25-50 by 38%, and < 25 by 41%. Eight centers reported a decline in LDR monotherapy case numbers in 2016. Number of center’s performing HDR brachytherapy increased in last five years. Relative uniformity in patient selection is noted, and LDR pre- and post-implant dosimetry adheres to published quality guidelines, with an average post-implant D₉₀ of > 145 Gy in 69% of centers in 2014 and 2015 compared to 63% in 2016. The median CT/US volume ratios were > 0.9 ≤ 1.0 (n = 4), > 1.0 ≤ 1.1 (n = 7), and > 1.1 (n = 2).

Conclusion

There is considerable prostate brachytherapy experience in the UK and Ireland. An apparent fall in LDR case numbers is noted. Maintenance of case numbers and ongoing compliance with published quality guidelines is important to sustain high quality outcomes.

New approach of ultra-focal brachytherapy for low- and intermediate-risk prostate cancer with custom-linked I-125 seeds: A feasibility study of optimal dose coverage

PURPOSE

To present the feasibility study of optimal dose coverage in ultra-focal brachytherapy (UFB) with multiparametric MRI for low- and intermediate-risk prostate cancer.

METHODS AND MATERIALS

UFB provisional dose plans for small target volumes (<7 cc) were calculated on a prostate training phantom to optimize the seeds number and strength. Clinical UFB consisted in a contour-based nonrigid registration (MRI/Ultrasound) to implant a fiducial marker at the location of the tumor focus. Dosimetry was performed with iodine-125 seeds and a prescribed dose of 160 Gy. On CT scans acquired at 1 month, dose coverage of 152 Gy to the ultra-focal gross tumor volume was evaluated. Registrations between magnetic resonance and CT scans were assessed on the first 8 patients with three software solutions: VariSeed, 3D Slicer, and Mirada, and quantitative evaluations of the registrations were performed. Impact of these registrations on the initial dose matrix was performed.

RESULTS

Mean differences between simulated dose plans and extrapolated Bard nomogram for UFB volumes were 36.3% (26-56) for the total activity, 18.3% (10-30) for seed strength, and 22.5% (16-38) for number of seeds. Registration method implemented in Mirada performed significantly better than VariSeed and 3D Slicer (p = 0.0117 and p = 0.0357, respectively). For dose plan evaluation between Mirada and VariSeed, D₁₀₀% (Gy) for ultra-focal gross tumor volume had a mean difference of 28.06 Gy, mean values being still above the objective of 152 Gy. D₉₀% for the prostate had a mean difference of 1.17 Gy. For urethra and rectum, dose limits were far below the recommendations.

CONCLUSIONS

This UFB study confirmed the possibility to treat with optimal dose coverage target volumes smaller than 7 cc.

IDEAL 2a Phase II Study of Ultrafocal Brachytherapy for Low- and Intermediate-risk Prostate Cancer

PURPOSE

Focal therapy of prostate cancer requires precise positioning of therapeutic agents within well-characterized index tumors (ITs). We assessed the feasibility of low-dose-rate ultrafocal brachytherapy.

METHODS AND MATERIALS

The present study was an institutional review board-approved European Clinical Trials Database-registered phase II protocol. Patients referred (October 2013 to August 2016) for active surveillance (prostate-specific antigen <10 ng/mL, cT1c-cT2a, Gleason score on referring biopsy specimens ≤6 (3+3), ≤3 positive biopsy cores, ≤50% of cancer) were preselected. Inclusion was confirmed when complementary image-guided biopsy findings informed a single Prostate Imaging Reporting and Data System (PI-RADS) ≥3, Gleason score ≤7a (3+4) lesion. A ultrasound-visible ancillary marker was positioned within the IT using a magnetic resonance imaging (MRI)/3-dimensional transrectal ultrasound (TRUS) elastic fusion-guided system (Koelis). Ultrafocal transperineal delivery of ¹²⁵I seeds used classic 2-dimensional TRUS (Bard-FlexFocus) and dose optimization (Variseed Treatment Planning System). Following Simon's optimal design, 17 patients were required to assess the feasibility of delivering ≥95% of the prescribed dose (160 Gy) to the IT (primary objective). Adverse events (Common Terminology Criteria for Adverse Events) and quality of life (5-item International Index of Erectile Function, International Prostate Symptom Score) were recorded. One-year control biopsy specimens were obtained from the IT and untreated segments.

RESULTS

Of the 44 preselected patients, 27 did not meet the inclusion criteria. Of the 17 ultrafocal brachytherapy-treated patients, 16 met the primary objective (per protocol success). The prescription dose was delivered to 14.5% ± 6.4% of the prostate volume, resulting in negligible urethral and rectal irradiation and toxicity. No recurrence was evidenced on the 1-year follow-up MRI studies or IT biopsy specimens. Seven nonclinically significant cancers and one Gleason score 7a (3+4) cancer (salvage prostatectomy) were observed in the untreated parenchyma.

CONCLUSIONS

Recent technology has allowed for selective and effective brachytherapy of small MRI targets.

Prostate cancer as a paradigm of multidisciplinary approach? Highlights from the Italian young radiation oncologist meeting

Aims and background

The diagnostic and therapeutic approach to prostate cancer has evolved rapidly in last decades. Young professionals need an update about these recent developments in order to improve the care of patients treated in their daily clinical practice.

Methods

On May 18, 2013, AIRO Giovani (the young section of the Italian Association of Radiation Oncology) organized a multidisciplinary meeting involving, as speakers, several young physicians from many parts of Italy actively involved in the diagnostic and therapeutic approach to prostate cancer. The meeting was specifically addressed to young physicians (radio-oncologists, urologists, medical oncologists) and presented the state-of-the-art of the diagnostic/therapeutic approach based on the latest evidence on the issue. Highlights of the congress are summarized and presented in this report.

Results

The large participation in the meeting (more than 120 participants were present) confirmed the interest of young radiation oncologists in improving their skills in prostate cancer management. The contributions of the speakers confirmed the need for regular updates, considering the promising results of recently published studies and the many new ongoing trials, on the diagnostic and therapeutic approaches to prostate cancer.

Conclusions

Multidisciplinary meetings are helpful to improve the skills of young professionals.

A retrospective analysis after low-dose-rate prostate brachytherapy with permanent 125I seed implant: clinical and dosimetric results in 70 patients

Aims and background

To evaluate the biochemical disease-free survival (bDFS) rate after 125I permanent-implant prostate brachytherapy.

Methods

Patients with a diagnosis of prostate adenocarcinoma and adequate PSA follow-up were selected for this retrospective study. Brachytherapy with permanent 125I seeds was performed as monotherapy, with a prescribed dose of 145 Gy to the prostate. Patients were stratified into recurrence risk groups according to the National Comprehensive Cancer Network (NCCN) guidelines. Biochemical failure was defined using the American Society of Therapeutic Radiology and Oncology (ASTRO) guidelines. The post-implant D90 (defined as the minimum dose covering 90% of the prostate) was obtained for each patient. Two cutoff points were used to test the correlation between D90 and bDFS results: 130 Gy and 140 Gy. bDFS was calculated from the implant date to the date of biochemical recurrence. Univariate and multivariate analysis were performed using the SPSS software and included clinical stage, pretreatment PSA, Gleason score (GS), androgen deprivation therapy, D90, and risk groups. In the univariate analysis we used a cutoff point of 5.89 ng/mL for PSA and 5 for GS.

Results

From June 2003 to April 2007, 70 patients were analyzed. The patients' distribution into recurrence risk groups was as follows: 39 patients (56%) in the low-risk group, 23 patients (33%) in the intermediate-risk group, and 8 patients (11%) in the high-risk group. At a median follow-up of 47 months (range, 19–70 months) bDFS was 88.4%, with a global actuarial 5-year bDFS of 86%. Disease-related factors including initial PSA level, GS and risk group were significant predictors of biochemical failure (P = 0.01, P = 0.01, P = 0.006, respectively). In multivariate analysis, risk group (P = 0.005) and GS (P = 0.03) were statistically significant.

Conclusion

Our data are in agreement with those in the literature and, despite the short follow-up, confirm the advantage of brachytherapy for patients at low and intermediate risk of recurrence.