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

Therapeutic prostate cancer interventions: a systematic review on pubic arch interference and needle positioning errors

INTRODUCTION

This study focuses on the quantification of and current guidelines on the hazards related to needle positioning in prostate cancer treatment: (1) access restrictions to the prostate gland by the pubic arch, so-called Pubic Arch Interference (PAI) and (2) needle positioning errors. Next, we propose solution strategies to mitigate these hazards.

METHODS

The literature search was executed in the Embase, Medline ALL, Web of Science Core Collection*, and Cochrane Central Register of Controlled Trials databases.

RESULTS

The literature search resulted in 50 included articles. PAI was reported in patients with various prostate volumes. The level of reported PAI varied between 0 and 22.3 mm, depending on the patient's position and the measuring method. Low-Dose-Rate Brachytherapy induced the largest reported misplacement errors, especially in the cranio-caudal direction (up to 10 mm) and the largest displacement errors were reported for High-Dose-Rate Brachytherapy in the cranio-caudal direction (up to 47 mm), generally increasing over time.

CONCLUSIONS

Current clinical guidelines related to prostate volume, needle positioning accuracy, and maximum allowable PAI are ambiguous, and compliance in the clinical setting differs between institutions. Solutions, such as steerable needles, assist in mitigating the hazards and potentially allow the physician to proceed with the procedure.This systematic review was performed in accordance with the PRISMA guidelines. The review was registered at Protocols.io (DOI: dx.doi.org/10.17504/protocols.io.6qpvr89eplmk/v1).

Uncertainty in magnetic resonance imaging-based prostate postimplant dosimetry: Results of a 10-person human observer study, and comparisons with automatic postimplant dosimetry

PURPOSE

Uncertainties in postimplant quality assessment (QA) for low-dose-rate prostate brachytherapy (LDRPBT) are introduced at two steps: seed localization and contouring. We quantified how interobserver variability (IoV) introduced in both steps impacts dose-volume-histogram (DVH) parameters for MRI-based LDRPBT, and compared it with automatically derived DVH parameters.

METHODS AND MATERIALS

Twenty-five patients received MRI-based LDRPBT. Seven clinical observers contoured the prostate and four organs at risk, and 4 dosimetrists performed seed localization, on each MRI. Twenty-eight unique manual postimplant QAs were created for each patient from unique observer pairs. Reference QA and automatic QA were also performed for each patient. IoV of prostate, rectum, and external urinary sphincter (EUS) DVH parameters owing to seed localization and contouring was quantified with coefficients of variation. Automatically derived DVH parameters were compared with those of the reference plans.

RESULTS

Coefficients of variation (CoVs) owing to contouring variability (CoVcontours) were significantly higher than those due to seed localization variability (CoVseeds) (median CoVcontours vs. median CoVseeds: prostate D90-15.12% vs. 0.65%, p < 0.001; prostate V100-5.36% vs. 0.37%, p < 0.001; rectum V100-79.23% vs. 8.69%, p < 0.001; EUS V200-107.74% vs. 21.18%, p < 0.001). CoVcontours were lower when the contouring observers were restricted to the 3 radiation oncologists, but were still markedly higher than CoVseeds. Median differences in prostate D90, prostate V100, rectum V100, and EUS V200 between automatically computed and reference dosimetry parameters were 3.16%, 1.63%, -0.00 mL, and -0.00 mL, respectively.

CONCLUSIONS

Seed localization introduces substantially less variability in postimplant QA than does contouring for MRI-based LDRPBT. While automatic seed localization may potentially help improve workflow efficiency, it has limited potential for improving the consistency and quality of postimplant dosimetry.

After ASCENDE-RT: Biochemical and survival outcomes following combined external beam radiotherapy and low-dose-rate brachytherapy for high-risk and unfavourable intermediate-risk prostate cancer, a population-based analysis

PURPOSE

To evaluate the outcomes of unfavorable intermediate-risk (UIR) and high-risk (HR) prostate cancer patients treated with combined external beam radiation therapy (EBRT) and low-dose-rate prostate brachytherapy (LDR-PB).

METHODS AND MATERIALS

A population-based cohort of 568 prostate cancer patients treated with combined EBRT and LDR-PB from 2010 to 2016 was analyzed. All patients received EBRT followed by LDR-PB boost. Outcomes were compared with the results for the brachytherapy arm of the ASCENDE-RT trial.

RESULTS

The median followup was 4.5 years. Sixty-nine percent (N = 391) had HR disease. Ninety-four percent of the HR and 57% of UIR were treated with androgen deprivation therapy (ADT) with a median duration of 12 months. The 5-year K-M biochemical progression-free survival (b-PFS), metastasis-free survival (MFS), and overall survival (OS) were 84 ± 2%, 90 ± 2%, and 88 ± 2%, similar to 89 ± 5%, 94 ± 4%, and 92 ± 4% for the ASCENDE-RT LDR-PB arm. The likelihood of achieving a PSA ≤0.2 ng/mL at 4 years was 88%, similar to 86% in the ASCENDE-RT LDR-PB arm. Thirty-three men (5.8%) would have been ineligible for ASCENDE-RT due to high-risk features. The 5-year K-M b-PFS, MFS and OS estimates were 86 ± 2%, 92 ± 1% and 89 ± 2% for the ASCENDE-RT eligible versus 56 ± 10% (p < 0.001), 73 ± 8% (p < 0.001), and 77 ± 9% (p = 0.098) for the ineligible patients.

CONCLUSIONS

In this population-based cohort, combining LDR-PB with pelvic EBRT (+/- ADT) achieves very favorable b-PFS that compares to the LDR-PB arm of the ASCENDE-RT, supporting the generalizability of those results. Men ineligible for ASCENDE-RT, based on prognostic features, have a much higher risk of biochemical recurrence and metastatic relapse.

Dosimetric outcomes of preoperative treatment planning with intraoperative optimization using stranded seeds in prostate brachytherapy

This study aimed to evaluate the quality of low-dose-rate (LDR) prostate brachytherapy (BT) based on treatment-related dosimetric outcomes. Data of 100 patients treated using LDR BT with stranded seeds from November 2012 to November 2017 were collected. The prescription dose for the prostate was 145 Gy. The dose constraints for the preoperative plan were: V100% ≥ 95%, V150% ≤ 60%, V200% ≤ 20% for the prostate; V100% for rectum, ≤ 1 cc; and V200 Gy for urethra, 0.0 cc. Intraoperative real-time dose calculation and postoperative dose distribution analysis on days 0 and 30 were performed. Median dosimetric outcomes on days 0 and 30 respective were: V100% 92.28% and 92.23%, V200% 18.63% and 25.02%, and D90% 150.88 Gy and 151.46 Gy for the prostate; V100% for the rectum, 0.11 cc and 0.22 cc; and V200 Gy for the urethra, 0.00 cc and 0.00 cc, respectively. Twenty patients underwent additional seed implantation to compensate for insufficient dose coverage of the prostate. No loss or substantial migration of seeds or severe toxicity was reported. With stranded seed implantation and intraoperative optimization, appropriate dose delivery to the prostate without excessive dose to the organs at risk could be achieved.

MRI-defined treatment margins, urinary toxicity, and PSA response in LDR prostate brachytherapy

PURPOSE

Implant quality metrics as measured by D90 and V100 do not address the adequacy of periprostatic margins. Relative margin deficiencies may relate to efficacy and margin excesses to post-implant toxicity. Our purpose is to determine MRI-defined treatment margins on prostate achieved with LDR brachytherapy.

METHODS AND MATERIALS

Post implant CT and MR images from 487 consecutive patients who received LDR brachytherapy from 2010 to 14 were co-registered. Four prostate quadrants were defined; anterior-superior (AS), posterior-superior (PS), anterior-inferior (AI), posterior-inferior (PI). Dosimetric variables were measured for prostate, and for each quadrant with a 0-, 2-, 3-, and 5-mm margin, as well as for the membranous urethra defined on MRI.

RESULTS

Prostate D90 (no margin) was associated with D90 to the volume enclosed by 2 mm, 3 mm and 5 mm margins (R2 = 0.9 - 1.0) with an average 7.1% decrease in dose per mm of margin. Mean D90 for PS, AI and PI quadrants were > 110% of prescription dose for margins of 2-, 3-, and 5-mm. AS quadrant mean D90s were generally lower (83.2% for 2 mm, 76.4% for 3 mm and 62.2% for 5 mm). Urethral strictures (n = 9) were associated with higher doses in the AI quadrant, and higher membranous urethral V125 (51 vs. 32%, p 0.013) and V150 (34.5 vs. 17.6%, p 0.01).

CONCLUSIONS

Using MR-CT post implant dosimetry, margin coverage up to 5 mm was excellent with less margin coverage in the AS quadrant. Late ≥ grade 2 toxicity and urinary strictures are more likely to occur with relative margin excess in the anterior-inferior quadrant and higher doses caudal to the prostate apex. Within this analysis, there was no relationship between treatment margins, and PSA outcome.

Computer-aided segmentation on MRI for prostate radiotherapy, Part I: Quantifying human interobserver variability of the prostate and organs at risk and its impact on radiation dosimetry

BACKGROUND AND PURPOSE

Quantifying the interobserver variability (IoV) of prostate and periprostatic anatomy delineation on prostate MRI is necessary to inform its use for treatment planning, treatment delivery, and treatment quality assessment.

MATERIALS AND METHODS

Twenty five prostate cancer patients underwent MRI-based low-dose-rate prostate brachytherapy (LDRPBT). The patients were scanned with a 3D T2-weighted sequence for treatment planning and a 3D T2/T1-weighted sequence for quality assessment. Seven observers involved with the LDRPBT workflow delineated the prostate, external urinary sphincter (EUS), seminal vesicles, rectum, and bladder on all 50 MRIs. IoV was assessed by measuring contour similarity metrics, differences in organ volumes, and differences in dosimetry parameters between unique observer pairs. Measurements from a group of 3 radiation oncologists (G1) were compared against those from a group consisting of the other 4 clinical observers (G2).

RESULTS

IoV of the prostate was lower for G1 than G2 (Matthew's correlation coefficient [MCC], G1 vs. G2: planning-0.906 vs. 0.870, p < 0.001; postimplant-0.899 vs. 0.861, p < 0.001). IoV of the EUS was highest of all the organs for both groups, but was lower for G1 (MCC, G1 vs. G2: planning-0.659 vs. 0.402, p < 0.001; postimplant-0.684 vs. 0.398, p < 0.001). Large differences in prostate dosimetry parameters were observed (G1 maximum absolute prostate ΔD90: planning-76.223 Gy, postimplant-36.545 Gy; G1 maximum absolute prostate ΔV100: planning-13.927%, postimplant-8.860%).

CONCLUSIONS

While MRI is optimal in the management of prostate cancer with radiation therapy, significant interobserver variability of the prostate and external urinary sphincter still exist.

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.

Understanding High-Dose, Ultra-High Dose Rate, and Spatially Fractionated Radiation Therapy

The National Cancer Institute's Radiation Research Program, in collaboration with the Radiosurgery Society, hosted a workshop called Understanding High-Dose, Ultra-High Dose Rate and Spatially Fractionated Radiotherapy on August 20 and 21, 2018 to bring together experts in experimental and clinical experience in these and related fields. Critically, the overall aims were to understand the biological underpinning of these emerging techniques and the technical/physical parameters that must be further defined to drive clinical practice through innovative biologically based clinical trials.

Dose to the dominant intraprostatic lesion using HDR vs. LDR monotherapy: A Phase II randomized trial

PURPOSE

To present the dosimetric results of a Phase II randomized trial comparing dose escalation to the MRI-defined dominant intraprostatic lesion (DIL) using either low-dose-rate (LDR) or high-dose-rate (HDR) prostate brachytherapy.

MATERIAL AND METHODS

Patients receiving prostate brachytherapy as monotherapy were randomized to LDR or HDR brachytherapy. Prostate and DILs were contoured on preoperative multiparametric MRI. These images were registered with transrectal ultrasound for treatment planning. LDR brachytherapy was preplanned using I-125 seeds. HDR brachytherapy used intraoperative transrectal ultrasound-based planning to deliver 27 Gy/2 fractions in separate implants. DIL location was classified as peripheral, central, or anterior. A student t-test compared DIL D₉₀ between modalities and DIL locations.

RESULTS

Of 60 patients, 31 underwent LDR and 29 HDR brachytherapy. Up to three DILs were identified per patient (100 total) with 74 peripheral, six central, and 20 anterior DILs. Mean DIL volume was 1.9 cc (SD: 1.7 cc) for LDR and 1.6 cc (SD 1.3 cc) for HDR (p = 0.279). Mean DIL D₉₀ was 151% (SD 30%) for LDR and 132% (SD 13%) for HDR. For LDR, mean peripheral DIL D₉₀ was 159% (SD 27%) and central or anterior 127% (SD 13%). HDR peripheral DILs received 137% (SD 12%) and central or anterior 119% (SD 7%). DIL D₉₀ for peripheral lesions was higher than anterior and central (p < 0.001).

CONCLUSIONS

DIL location affects dose escalation, particularly because of urethral proximity, such as for anterior and central DILs. HDR brachytherapy may dose escalate better when target DIL is close to critical organs.

A novel radiation-shielding undergarment using tungsten functional paper for patients with permanent prostate brachytherapy

Tungsten functional paper (TFP) is a paper-based radiation-shielding material, which is lead-free and easy to cut. We developed a radiation protection undergarment using TFP for prostate cancer patients treated with permanent 125I seed implantation (PSI). The aim of this study was to evaluate the shielding ability of the undergarment with respect to household contacts and members of the public. Between October 2016 and April 2017, a total of 10 prostate cancer patients treated with PSI were enrolled in this prospective study. The external radiation exposure from each patient 1 day after PSI was measured with and without the undergarment. Measurements were performed using a survey meter at 100 cm from the surface of the patient's body. The exposure rates were measured from five directions: anterior, anteriorly oblique, lateral, posteriorly oblique, and posterior. The measured radiation exposure rates without the undergarment, expressed as mean ± standard deviation, from the anterior, anteriorly oblique, lateral, posteriorly oblique, and posterior directions were 1.28 ± 0.43 μSv/h, 0.70 ± 0.34 μSv/h, 0.21 ± 0.062 μSv/h, 0.65 ± 0.33 μSv/h and 1.24 ± 0.41 μSv/h, respectively. The undergarment was found to have (mean ± standard deviation) shielding abilities of 88.7 ± 5.8%, 44.0 ± 42.1%, 50.6 ± 15.9%, 72.9 ± 27.0% and 90.4 ± 10.7% from the anterior, anteriorly oblique, lateral, posteriorly oblique, and posterior directions, respectively. In conclusion, this shielding undergarment is a useful device that has the potential to reduce radiation exposure for the general public and the patient's family.

Fusion of Intraoperative Transrectal Ultrasound Images with Post-implant Computed Tomography and Magnetic Resonance Imaging

Purpose

To compare the impact of the fusion of intraoperative transrectal ultrasound (TRUS) images with day 30 computed tomography (CT) and magnetic resonance imaging (MRI) on prostate volume and dosimetry.

Methods and materials

Seventy-five consecutive patients with CT and MRI obtained on day 30 with a Fast Spin Echo T2-weighted magnetic resonance (MR) sequence were analyzed. A rigid manual registration was performed between the intraoperative TRUS and day-30 CT based on the prostate volume. A second manual rigid registration was performed between the intraoperative TRUS and the day-30 MRI. The prostate contours were manually modified on CT and MRI. The difference in prostate volume and dosimetry between CT and MRI were compared.

Results

Prostate volume was on average 8% (standard deviation (SD) ± 16%) larger on intraoperative TRUS than on CT and 6% (18%) larger than on MRI. In 48% of the cases, the difference in volume on CT was > 10% compared to MRI. The difference in prostate volume between CT and MRI was inversely correlated to the difference in D90 (minimum dose that covers 90% of the prostate volume) between CT and MRI (r = -0.58, P < .001). A D90 < 90% was found in 5% (n = 4) on MRI and in 10% (n = 7) on CT (Fisher exact test one-sided P = .59), but in no patient was the D90 < 90% on both MRI and CT.

Conclusions

When fusing TRUS images with CT and MRI, the differences in prostate volume between those modalities remain clinically important in nearly half of the patients, and this has a direct influence on how implant quality is evaluated.

Brachytherapy monotherapy may be sufficient for a subset of patients with unfavorable intermediate risk prostate cancer

PURPOSE/OBJECTIVE(S)

Brachytherapy (BT) monotherapy is a well-established treatment modality for favorable intermediate risk (FIR) prostate cancer. However, patients with unfavorable intermediate risk (UIR) disease are often recommended trimodality therapy involving BT, androgen deprivation therapy (ADT), and external beam radiation therapy (EBRT). We sought to investigate the relative benefit of supplemental therapies (ADT and/or EBRT) for FIR and UIR prostate cancer in a large dataset.

MATERIALS/METHODS

We identified 3,723 patients with intermediate risk prostate cancer treated with BT between 1997 and 2013, including 1,989 and 1,734 patients with FIR and UIR disease, respectively. For the FIR cohort, Fine and Gray's competing risks regression model was used to evaluate whether there was a difference in prostate cancer specific mortality (PCSM) between BT vs. BT + supplemental therapy (ADT, EBRT, or both). For the UIR cohort, this regression model was used to evaluate whether supplemental ADT, EBRT, or both decreased PCSM beyond BT alone. Both regression models were adjusted for clinical and treatment-related factors.

RESULTS

The median follow-up periods were 7.7 years (interquartile range: 5.4-10.5) for the FIR cohort and 7.8 years (interquartile range: 5.3-10.6) for the UIR cohort. For the FIR cohort, there was no difference in PCSM between BT monotherapy vs. BT + supplemental therapy (adjusted hazard ratio [AHR] = 1.70; 95% CI: 0.46-6.29; P = 0.43). For the UIR cohort, supplemental EBRT (AHR = 2.66; 95% CI: 1.12-6.34; P = 0.03), ADT (AHR = 0.96; 95% CI: 0.38-2.43; P = 0.93), or both (AHR = 1.46; 95% CI: 0.42-5.01; P = 0.55) were not associated with improved PCSM compared with BT alone.

CONCLUSION

In our analysis, supplemental therapies did not offer an improvement in PCSM compared with BT alone for FIR or UIR prostate cancers. Further prospective clinical trials are required to determine whether BT monotherapy may be sufficient for a subset of patients with UIR disease.

Clinical outcomes of 125I brachytherapy with and without external-beam radiation therapy for localized prostate cancer: results from 300 patients at a single institution in Japan

The aim of this study was to determine the outcomes and adverse events for 300 men with prostate cancer treated with 125iodine (125I) brachytherapy with and without external-beam radiation therapy (EBRT) at a single institution in Japan. Between February 2005 and November 2011, 300 consecutive patients with clinically localized prostate cancer were treated with 125I brachytherapy at the Nagoya University Hospital. A total of 271 men were treated with implants with doses of 145 Gy, and 29 men were treated with implants with doses of 110 Gy combined with EBRT (40-50 Gy/20-25 fractions). The median patient age was 69 years (range, 53-83 years). The median follow-up period was 53 months (range, 5-99 months). According to the National Comprehensive Cancer Network risk classification, 132 men (44%) had low-risk, 147 men (29%) had intermediate-risk and 21 men (7%) had high-risk disease. The 5-year overall survival rate, biochemical relapse-free survival rate, and disease-specific survival rates were 93.5%, 97.3% and 98.5%, respectively. Two men (0.6%) died of prostate cancer and 10 men (3.3%) died of other causes. Seventeen men (5.6%) experienced Grade 2 rectal bleeding in all: 12 (41.4%) of 29 in brachytherapy with EBRT, and 5 (1.8%) of 271 in brachytherapy alone. The rates of Grade 2 and 3 genitourinary toxicity were 1.0% and 1.7%, respectively. Excellent local control was achieved at our hospital for localized prostate cancer with 125I brachytherapy with and without EBRT. Gastrointestinal and genitourinary toxicities were acceptable.

Real-time intraoperative evaluation of implant quality and dose correction during prostate brachytherapy consistently improves target coverage using a novel image fusion and optimization program

PURPOSE

Our purpose was to describe the process and outcome of performing postimplantation dosimetric assessment and intraoperative dose correction during prostate brachytherapy using a novel image fusion-based treatment-planning program.

METHODS AND MATERIALS

Twenty-six consecutive patients underwent intraoperative real-time corrections of their dose distributions at the end of their permanent seed interstitial procedures. After intraoperatively planned seeds were implanted and while the patient remained in the lithotomy position, a cone beam computed tomography scan was obtained to assess adequacy of the prescription dose coverage. The implanted seed positions were automatically segmented from the cone-beam images, fused onto a new set of acquired ultrasound images, reimported into the planning system, and recontoured. Dose distributions were recalculated based upon actual implanted seed coordinates and recontoured ultrasound images and were reviewed. If any dose deficiencies within the prostate target were identified, additional needles and seeds were added. Once an implant was deemed acceptable, the procedure was completed, and anesthesia was reversed.

RESULTS

When the intraoperative ultrasound-based quality assurance assessment was performed after seed placement, the median volume receiving 100% of the dose (V100) was 93% (range, 74% to 98%). Before seed correction, 23% (6/26) of cases were noted to have V100 <90%. Based on this intraoperative assessment and replanning, additional seeds were placed into dose-deficient regions within the target to improve target dose distributions. Postcorrection, the median V100 was 97% (range, 93% to 99%). Following intraoperative dose corrections, all implants achieved V100 >90%.

CONCLUSIONS

In these patients, postimplantation evaluation during the actual prostate seed implant procedure was successfully applied to determine the need for additional seeds to correct dose deficiencies before anesthesia reversal. When applied, this approach should significantly reduce intraoperative errors and chances for suboptimal dose delivery during prostate brachytherapy.

Adaptive cone-beam CT planning improves long-term biochemical disease-free survival for 125I prostate brachytherapy

PURPOSE

Determining the independent effect of additional intraoperative adaptive C-arm cone-beam CT (CBCT) planning vs. transrectal ultrasound (TRUS)-guided interactive planning alone in ¹²⁵I brachytherapy for prostate cancer (PCa) on biochemical disease-free survival (BDFS).

METHODS AND MATERIALS

T1/T2-stage PCa patients receiving TRUS-guided brachytherapy from 2000 to 2014 were analyzed. From October 2006, patients received additional intraoperative adaptive CBCT planning for dosimetric evaluation and subsequent remedial seed placement in underdosed areas. Patients were stratified according to the National Comprehensive Cancer Network (NCCN) risk classification. Kaplan-Meier analysis was used to estimate BDFS (primary outcome), overall survival, and PCa-specific survival (secondary outcomes). Cox regression was used to assess the relation between CBCT use and biochemical failure (BF) and overall mortality.

RESULTS

In all, 1623 patients were included. Median followup was 99 months (interquartile range 70-115) for TRUS patients (n = 613) and 51 months (interquartile range 29-70) for CBCT patients (n = 1010). BF occurred 203 times and 206 patients died, 26 from PCa. For TRUS and CBCT patients, 7-year BDFS was 87.2% vs. 93.5% (log rank: p = 0.04) for low, 75.9% vs. 88.5% (p < 0.001) for intermediate, and 57.1% vs. 85.0% for high-risk patients (p < 0.001). For TRUS and CBCT patients, 7-year PCa-specific survival was 96.0% vs. 100% (p < 0.0001). After Cox regression, CBCT patients had lower hazard of BF: hazard ratio (HR) 0.25 (95% confidence interval [CI]: 0.18-0.33; p < 0.0001). Corrected for confounders, CBCT remained a predictor of BF: HR 0.51 (95% CI: 0.31-0.86; p = 0.01) but not for overall mortality: HR 0.66 (95% CI: 0.40-1.07; p = 0.09).

CONCLUSIONS

Additional intraoperative adaptive CBCT planning in ¹²⁵I prostate brachytherapy leads to a significant increase in BDFS in all NCCN risk groups.

Androgen Suppression Combined with Elective Nodal and Dose Escalated Radiation Therapy (the ASCENDE-RT Trial): An Analysis of Survival Endpoints for a Randomized Trial Comparing a Low-Dose-Rate Brachytherapy Boost to a Dose-Escalated External Beam Boost for High- and Intermediate-risk Prostate Cancer

PURPOSE

To report the primary endpoint of biochemical progression-free survival (b-PFS) and secondary survival endpoints from ASCENDE-RT, a randomized trial comparing 2 methods of dose escalation for intermediate- and high-risk prostate cancer.

METHODS AND MATERIALS

ASCENDE-RT enrolled 398 men, with a median age of 68 years; 69% (n=276) had high-risk disease. After stratification by risk group, the subjects were randomized to a standard arm with 12 months of androgen deprivation therapy, pelvic irradiation to 46 Gy, followed by a dose-escalated external beam radiation therapy (DE-EBRT) boost to 78 Gy, or an experimental arm that substituted a low-dose-rate prostate brachytherapy (LDR-PB) boost. Of the 398 trial subjects, 200 were assigned to DE-EBRT boost and 198 to LDR-PB boost. The median follow-up was 6.5 years.

RESULTS

In an intent-to-treat analysis, men randomized to DE-EBRT were twice as likely to experience biochemical failure (multivariable analysis [MVA] hazard ratio [HR] 2.04; P=.004). The 5-, 7-, and 9-year Kaplan-Meier b-PFS estimates were 89%, 86%, and 83% for the LDR-PB boost versus 84%, 75%, and 62% for the DE-EBRT boost (log-rank P<.001). The LDR-PB boost benefited both intermediate- and high-risk patients. Because the b-PFS curves for the treatment arms diverge sharply after 4 years, the relative advantage of the LDR-PB should increase with longer follow-up. On MVA, the only variables correlated with reduced overall survival were age (MVA HR 1.06/y; P=.004) and biochemical failure (MVA HR 6.30; P<.001). Although biochemical failure was associated with increased mortality and randomization to DE-EBRT doubled the rate of biochemical failure, no significant overall survival difference was observed between the treatment arms (MVA HR 1.13; P=.62).

CONCLUSIONS

Compared with 78 Gy EBRT, men randomized to the LDR-PB boost were twice as likely to be free of biochemical failure at a median follow-up of 6.5 years.

Low-dose rate brachytherapy with I-125 seeds has an excellent 5-year outcome with few side effects in patients with low-risk prostate cancer

BACKGROUND

Low-dose rate brachytherapy (LDR-BT) has been used in Sweden for more than a decade for treatment of low-risk prostate cancer. This study presents the outcome for patients treated with LDR-BT at a single institution with focus on the association between dose and biochemical failure-free survival (BFFS).

METHODS

In total 195 patients were treated with LDR-BT between 2004 and 2008. The patients were followed systematically for side effects for at least one year. PSA levels were followed regularly from three months and for at least five years. Outcome was analyzed in relation to clinical variables at baseline and to radiotherapy data.

RESULTS

Kaplan-Meier estimated BFFS at five years was 95.7%. Dose to the prostate in terms of D90% was significantly associated with BFFS [HR 0.90 (95%CI 0.83-0.96), p = 0.002].

CONCLUSION

Out data confirmed that absorbed dose is a predictive factor for BFFS for low-risk patients without androgen deprivation therapy. With our treatment routines and dosimetry, a D90% in the range of 170-180 Gy gives excellent outcomes with acceptable toxicity for patients with low-risk prostate cancer.

Low dose rate brachytherapy (LDR-BT) as monotherapy for early stage prostate cancer in Italy: practice and outcome analysis in a series of 2237 patients from 11 institutions

OBJECTIVE

Low-dose-rate brachytherapy (LDR-BT) in localized prostate cancer is available since 15 years in Italy. We realized the first national multicentre and multidisciplinary data collection to evaluate LDR-BT practice, given as monotherapy, and outcome in terms of biochemical failure.

METHODS

Between May 1998 and December 2011, 2237 patients with early-stage prostate cancer from 11 Italian community and academic hospitals were treated with iodine-125 ((125)I) or palladium-103 LDR-BT as monotherapy and followed up for at least 2 years. (125)I seeds were implanted in 97.7% of the patients: the mean dose received by 90% of target volume was 145 Gy; the mean target volume receiving 100% of prescribed dose (V100) was 91.1%. Biochemical failure-free survival (BFFS), disease-specific survival (DSS) and overall survival (OS) were estimated using Kaplan-Meier method. Log-rank test and multivariable Cox regression were used to evaluate the relationship of covariates with outcomes.

RESULTS

Median follow-up time was 65 months. 5- and 7-year DSS, OS and BFFS were 99 and 98%, 94 and 89%, and 92 and 88%, respectively. At multivariate analysis, the National Comprehensive Cancer Network score (p < 0.0001) and V100 (p = 0.09) were correlated with BFFS, with V100 effect significantly different between patients at low risk and those at intermediate/high risk (p = 0.04). Short follow-up and lack of toxicity data represent the main limitations for a global evaluation of LDR-BT.

CONCLUSION

This first multicentre Italian report confirms LDR-BT as an excellent curative modality for low-/intermediate-risk prostate cancer.

ADVANCES IN KNOWLEDGE

Multidisciplinary teams may help to select adequately patients to be treated with brachytherapy, with a direct impact on the implant quality and, possibly, on outcome.

Ten-year outcomes using low dose rate brachytherapy for localised prostate cancer: An update to the first Australian experience

INTRODUCTION

To report long-term prostate-specific antigen (PSA) and toxicity outcomes for patients with localised prostate cancer treated with Iodine-125 permanent implantation at a single Australian centre.

METHODS

Between September 1994 and November 2007, 207 patients at Sir Charles Gairdner Hospital with localised prostate cancer were consecutively treated with Iodine-125 permanent interstitial implantation. Post-therapy assessment was performed three times a month and included clinical review and biochemical (PSA) evaluation. PSA progression was evaluated using the Phoenix (nadir + 2.0) definition. Treatment-related morbidity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 guidelines. The rate of biochemical failure was calculated by Kaplan-Meier plots. Univariate and multivariate analyses were performed to evaluate outcomes by pre-treatment clinical prognostic factors and radiation dosimetry.

RESULTS

Median follow-up was 7.8 years. The 10-year biochemical disease-free survival (bDFS) for the entire cohort was 89%. Ten-year bDFS estimates by pre-treatment risk group were 96% for low-risk, 83% for intermediate-risk and 50% for high-risk disease. On multivariate analysis, pre-treatment PSA was an independent predictor of bDFS. D90 dose did not show a statistically significant effect on bDFS. The peak incidences of late grade 3 or higher urinary and rectal toxicities were 10.7% and 1.1% respectively.

CONCLUSION

Excellent long-term biochemical control was demonstrated with Iodine-125 permanent interstitial implantation in appropriately selected patients with prostate cancer. The results of our single centre experience are comparable with those of other single institutions.

Rectal Ulcers and Rectoprostatic Fistulas after (125)I Low Dose Rate Prostate Brachytherapy

PURPOSE

Radiation induced rectal ulcers and fistulas are rare but significant complications of low dose rate prostate brachytherapy for localized prostate cancer. We describe the incidence of ulcers and fistulas, and associated risk factors.

MATERIALS AND METHODS

We reviewed the records of 4,690 patients with localized prostate cancer who were treated with low dose rate (125)I prostate brachytherapy to a dose of 144 Gy with or without 6 months of androgen deprivation therapy. Patient, disease, comorbidity, treatment, dosimetric and posttreatment intervention factors were analyzed for an association with ulcer or fistula formation.

RESULTS

At a median followup of 53 months 21 cases were identified, including 15 rectal ulcer cases, of which 6 progressed to fistulas, and an additional 6 cases of fistulas with no prior documented ulcers. Overall 9 rectal ulcer cases (0.19%) and 12 fistula cases (0.26%) were identified. In 8 of 15 patients ulcers healed with conservative management. No fistulas healed without surgical management. Two patients with fistulas died. Eight patients diagnosed with rectal ulcers subsequently underwent rectal biopsies, after which fistulas developed in 3. One patient with a de novo fistula underwent a preceding biopsy. Urinary interventions such as transurethral resection of the prostate were performed after brachytherapy in 5 of 12 patients with fistulas compared to 0 of 9 with ulcers alone. Argon plasma coagulation of the rectum for hematochezia was performed after brachytherapy in 3 of 12 patients with fistulas.

CONCLUSIONS

Rates of post-brachytherapy rectal ulcers and fistulas are low as previously described. Post-brachytherapy interventions such as rectal biopsy, argon coagulation and urinary intervention may increase the risk of fistulas.

Is it necessary to perform week three dosimetric analysis in low-dose-rate brachytherapy for prostate cancer when day 0 dosimetry is done? A quality assurance assessment

PURPOSE

To determine whether computed tomography/magnetic resonance imaging-based day 0 (d0) dosimetry is a meaningful predictor of day 21 (d21) dosimetry in low-dose-rate brachytherapy for localized prostate cancer.

METHODS AND MATERIALS

The study population consisted of 277 men with localized (T1-2 N0 M0), low-/intermediate-risk prostate cancer treated with low-dose-rate brachytherapy. Computed tomography/magnetic resonance imaging fusion was used for postimplant dosimetry at d0 and d21. Logistic regression was used to construct receiver operating characteristic curves for achieving each constraint at d21, based on d0 D90 and V100, and Youden's index was used to evaluate cutpoints. Freedom from biochemical failure (FBCF) was estimated with the Kaplan-Meier method.

RESULTS

The median d0 D90 increased from 133 to 150 Gy at d21, and median d0 V100 increased from 87% to 91%. For achieving the D90 constraint at d21, the optimal cut-point for d0 D90 was 135 Gy, with 84% of these patients maintaining a d21 D90 > 145 Gy. For achieving the D90 constraint at d21, the optimal cut-point for d0 V100 was 87%, with 83% of these patients maintained a d21 V100 > 90%. There was no improvement in FBCF in patients with a d0 D90 > 135 Gy or D90 > 145 Gy. Similarly, there was no improvement in FBCF in patients with a d0 V100 > 87% or V100 > 90%.

CONCLUSIONS

Meeting dosimetric constraints on d0 does not obviate d21 dosimetric analysis. Constraints used for dose prescriptions on d0 are not the ideal predictors of d21 dosimetry.

A dose-response analysis of biochemical control outcomes after (125)I monotherapy for patients with favorable-risk prostate cancer

PURPOSE

To define the optimal dose for (125)I prostate implants by correlating postimplantation dosimetry findings with biochemical failure and toxicity.

METHODS AND MATERIALS

Between 2003 and 2009, 683 patients with prostate cancer were treated with (125)I prostate brachytherapy without supplemental external beam radiation therapy and were followed up for a median time of 80 months. Implant dose was defined as the D90 (the minimal dose received by 90% of the prostate) on postoperative day 1 and 1 month after implantation. Therefore, 2 dosimetric variables (day 1 D90 and day 30 D90) were analyzed for each patient. We investigated the dose effects on biochemical control and toxicity.

RESULTS

The 7-year biochemical failure-free survival (BFFS) rate for the group overall was 96.4% according to the Phoenix definition. A multivariate analysis found day 1 D90 and day 30 D90 to be the most significant factors affecting BFFS. The cutoff points for day 1 D90 and day 30 D90, calculated from ROC curves, were 163 Gy and 175 Gy, respectively. By use of univariate analysis, various dosimetric cutoff points for day 30 D90 were tested. We found that day 30 D90 cutoff points from 130 to 180 Gy appeared to be good for the entire cohort. Greater D90s were associated with an increase in late genitourinary or gastrointestinal toxicity ≥ grade 2, but the increase was not statistically significant.

CONCLUSIONS

Improvements in BFFS rates were seen with increasing D90 levels. Day 30 D90 doses of 130 to 180 Gy were found to serve as cutoff levels. For low-risk and low-tier intermediate-risk prostate cancer patients, high prostate D90s, even with doses exceeding 180 Gy, achieve better treatment results and are feasible.

Regional dose metrics as predictors of biochemical failure and local recurrence after low-dose-rate prostate brachytherapy

PURPOSE/OBJECTIVES

To assess regional dose metrics as predictors of disease relapse after low-dose-rate prostate brachytherapy.

METHODS AND MATERIALS

A cohort of 2000 consecutive patients with prostate cancer treated with iodine-125 low-dose-rate prostate brachytherapy monotherapy was implanted between July 1998 and November 2007. Within this group, 89 patients had disease relapse, 13 of whom had local failure by clinical or histopathologic criteria. Postoperative computed tomography scans were available for 96.3% of cases, resulting in a data set composed of 87 relapses (including all 13 local relapses) and 1839 nonrelapsed controls. Using the VariSeed 8.0.2 software, we divided the original prostate contours into four quadrants: anterior-superior (ASQ), posterior-superior, anterior-inferior (AIQ), and posterior-inferior. DVH-derived dosimetric parameters were calculated for the whole prostate and each quadrant.

RESULTS

Gleason score, prostate-specific antigen, and the use of androgen-deprivation therapy were predictive of disease relapse in a multivariate Cox model. Whole prostate dose metrics did not predict biochemical or local relapse. Dosimetric coverage was sparsest in the ASQ. Despite low values, dose to the ASQ was not predictive of relapse, nor were doses to the remaining three quadrants. AIQ coverage was predictive of local relapse in multivariate Cox model (p = 0.042). However, the AIQ dose metrics exhibited a large variance and on bootstrap analysis, a p value of <0.05 was seen in only 51% of 1000 iterations.

CONCLUSIONS

Consistent with previous reports, whole-prostate dose metrics were not predictive of disease relapse (any) or local relapse in our patients. Although significant ASQ underdosage relative to other prostate regions was observed, ASQ dose coverage did not correlate with relapse.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Late urinary side effects 10 years after low-dose-rate prostate brachytherapy: population-based results from a multiphysician practice treating with a standardized protocol and uniform dosimetric goals

PURPOSE

To determine late urinary toxicity (>12 months) in a large cohort of uniformly treated low-dose-rate prostate brachytherapy patients.

METHODS AND MATERIALS

From 1998 to 2009, 2709 patients with National Comprehensive Cancer Network-defined low-risk and low-tier intermediate-risk prostate cancer were treated with Iodine 125 ((125)I) low-dose-rate prostate brachytherapy; 2011 patients with a minimum of 25 months of follow-up were included in the study. Baseline patients, treatment, implant factors, and late urinary toxicity (Radiation Therapy Oncology Group [RTOG] grading system and International Prostate Symptom Score [IPSS]) were recorded prospectively. Time to IPSS resolution, late RTOG genitourinary toxicity was examined with Kaplan-Meier and log-rank tests. Cox proportional hazards regression was done for individual covariates and multivariable models.

RESULTS

Median follow-up was 54.5 months (range, 2-13 years). Actuarial toxicity rates reached 27% and 10% (RTOG ≥2 and ≥3, respectively) at 9-13 years. Symptoms resolved quickly in the majority of patients (88% in 6-12 months). The prevalence of RTOG 0, 1, 2, 3, and 4 toxicity with a minimum of 7 years' follow-up was 70%, 21%, 6.4%, 2.3%, and 0.08%, respectively. Patients with a larger prostate volume, higher baseline IPSS, higher D90, acute toxicity, and age >70 years had more late RTOG ≥2 toxicity (all P≤.02). The IPSS resolved slower in patients with lower baseline IPSS and larger ultrasound prostate volume, those not receiving androgen deprivation therapy, and those with higher D90. The crude rate of RTOG 3 toxicity was 6%. Overall the rate of transurethral resection of the prostate was 1.9%; strictures, 2%; incontinence, 1.3%; severe symptoms, 1.8%; late catheterization, 1.3%; and hematuria, 0.8%. The majority (80%) resolved their symptoms in 6-12 months.

CONCLUSION

Long-term urinary toxicity after brachytherapy is low. Although actuarial rates increase with longer follow-up (27% RTOG 2 and 10% RTOG 3 at 13 years), symptoms resolve relatively quickly; between 5 and 13 years' follow-up, >90% of patients have minimal urinary toxicity. Refining patient selection criteria, planning, and treatment delivery may further reduce toxicity.