Use of pelvic CT scanning to evaluate pubic arch interference of transperineal prostate brachytherapy

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).

Dosimetric benefits and preclinical performance of steerable needles in HDR prostate brachytherapy

Prostate cancer patients with an enlarged prostate and/or excessive pubic arch interference (PAI) are generally considered non-eligible for high-dose-rate (HDR) brachytherapy (BT). Steerable needles have been developed to make these patients eligible again. This study aims to validate the dosimetric impact and performance of steerable needles within the conventional clinical setting. HDR BT treatment plans were generated, needle implantations were performed in a prostate phantom, with prostate volume > 55 cm3 and excessive PAI of 10 mm, and pre- and post-implant dosimetry were compared considering the dosimetric constraints: prostate V100 > 95 % (13.50 Gy), urethra D0.1cm3 < 115 % (15.53 Gy) and rectum D1cm3 < 75 % (10.13 Gy). The inclusion of steerable needles resulted in a notable enhancement of the dose distribution and prostate V100 compared to treatment plans exclusively employing rigid needles to address PAI. Furthermore, the steerable needle plan demonstrated better agreement between pre- and post-implant dosimetry (prostate V100: 96.24 % vs. 93.74 %) compared to the rigid needle plans (79.13 % vs. 72.86 % and 87.70 % vs. 81.76 %), with no major changes in the clinical workflow and no changes in the clinical set-up. The steerable needle approach allows for more flexibility in needle positioning, ensuring a highly conformal dose distribution, and hence, HDR BT is a feasible treatment option again for prostate cancer patients with an enlarged prostate and/or excessive PAI.

A Model to Predict Deflection of an Active Tendon-Driven Notched Needle Inside Soft Tissue

The last decade has witnessed major progress in the field of minimally invasive and robotic-assisted surgeries. Needle insertion, a minimally invasive technique, has proven its efficacy in procedures such as brachytherapy, ablation, drug delivery, and biopsy. Manual needle steering inside tissue is a challenging task due to complex needle-tissue interactions, needle and tissue movement, lack of actuation and control, as well as poor sensing and visualization. Recently, active tendon-driven notched needles, and robotic manipulation systems have been proposed to assist surgeons to guide the needles in desired trajectories toward target positions. This work introduces a new deflection model for the active tendon-driven notched needle steering inside soft tissue for intention to use in model-based robotic control. The model is developed to predict needle deflection in a single-layer tissue. To validate the proposed deflection model, five sets of needle insertion experiments with a bevel-tipped active needle into single-layer phantom tissues were performed. A real-time robot-assisted ultrasound tracking method was used to track the needle tip during needle insertion. It was shown that the model predicts needle deflection with an average error of 0.58 ± 0.14 mm for the bevel-tipped active needle insertion into a single-layer phantom tissue.

Axially rigid steerable needle with compliant active tip control

Steerable instruments allow for precise access to deeply-seated targets while sparing sensitive tissues and avoiding anatomical structures. In this study we present a novel omnidirectional steerable instrument for prostate high-dose-rate (HDR) brachytherapy (BT). The instrument utilizes a needle with internal compliant mechanism, which enables distal tip steering through proximal instrument bending while retaining high axial and flexural rigidity. Finite element analysis evaluated the design and the prototype was validated in experiments involving tissue simulants and ex-vivo bovine tissue. Ultrasound (US) images were used to provide visualization and shape-reconstruction of the instrument during the insertions. In the experiments lateral tip steering up to 20 mm was found. Manually controlled active needle tip steering in inhomogeneous tissue simulants and ex-vivo tissue resulted in mean targeting errors of 1.4 mm and 2 mm in 3D position, respectively. The experiments show that steering response of the instrument is history-independent. The results indicate that the endpoint accuracy of the steerable instrument is similar to that of the conventional rigid HDR BT needle while adding the ability to steer along curved paths. Due to the design of the steerable needle sufficient axial and flexural rigidity is preserved to enable puncturing and path control within various heterogeneous tissues. The developed instrument has the potential to overcome problems currently unavoidable with conventional instruments, such as pubic arch interference in HDR BT, without major changes to the clinical workflow.

Steering a Tendon-Driven Needle in High-Dose-Rate Prostate Brachytherapy for Patients with Pubic Arch Interference

High-dose-rate brachytherapy (HDR BT) is a radiation therapy that places radioactive sources at cancerous tissue using needles. HDR BT offers better dose conformality and sparing of clinical structures, lower operator dependency, and fewer acute irritative symptoms compared to the other form of BT (low-dose-rate (LDR)). However, use of HDR BT is limited for patients with pubic arch interference, where the transperineal path to the prostate is blocked. This study aims to introduce a tendon-driven needle that can bend inside tissue to reach desired positions inside prostate. Initial experiments in a phantom tissue showed the feasibility of the needle to get around the pubic arch for placement at hard-to-reach target positions.

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.

Predicting pubic arch interference in permanent prostate brachytherapy based on the specific parameters derived from nuclear magnetic resonance imaging

PURPOSE

The aim of this study was to establish a more reliable method to predict pubic arch interference (PAI) before permanent prostate brachytherapy.

MATERIAL AND METHODS

We retrospectively analyzed the nuclear magnetic resonance imaging (MRI) results of forty patients with prostate cancer, who were treated with permanent implantation of 125I seeds (permanent brachytherapy). We measured and calculated six parameters based on the MRI results: 1. The prostate volume (PV); 2. The angle of the pubic arch (AoPA); 3. The angle of PAI (AoPAI, pubic symphysis level); 4. The height of PAI (hPAI, pubic symphysis level); 5. The maximum angle of PAI (AoPAIMax); 6. The maximum height of PAI (hPAIMax). We then tested which parameters could accurately predict PAI through receiver operating characteristic (ROC) curve analysis.

RESULTS

The results of this study demonstrated that AoPAI, hPAI, hPAIMax, and AoPAIMax could predict PAI. Out of forty cases in our research, 10 cases were with PAI and 30 cases without PAI during the operation. The areas under the ROC curve for PV, AoPA, AoPAI (pubic symphysis level), hPAI (pubic symphysis level), AoPAIMax, and hPAIMax were 0.592, 0.567, 0.957, 0.940, 0.927, and 0.877, respectively. The AoPAI (pubic symphysis level), hPAI (pubic symphysis level), AoPAIMax, and hPAIMax were statistically correlated with PAI. The boundary values were 26.32°, 1.13 cm, 28.37°, and 1.51 cm, respectively.

CONCLUSIONS

This new method derived from MRI has predictive value, as AoPAI, hPAI, hPAIMax, and AoPAIMax could predict PAI. Taking other factors into consideration, we suggest the use of AoPAI as a novel and very reliable predictor of PAI.

Permanent prostate brachytherapy postimplant magnetic resonance imaging dosimetry using positive contrast magnetic resonance imaging markers

PURPOSE

Permanent prostate brachytherapy dosimetry using computed tomography-magnetic resonance imaging (CT-MRI) fusion combines the anatomic detail of MRI with seed localization on CT but requires multimodality imaging acquisition and fusion. The purpose of this study was to compare the utility of MRI only postimplant dosimetry to standard CT-MRI fusion-based dosimetry.

METHODS AND MATERIALS

Twenty-three patients undergoing permanent prostate brachytherapy with use of positive contrast MRI markers were included in this study. Dose calculation to the whole prostate, apex, mid-gland, and base was performed via standard CT-MRI fusion and MRI only dosimetry with prostate delineated on the same T2 MRI sequence. The 3-dimensional (3D) distances between seed positions of these two methods were also evaluated. Wilcoxon-matched-pair signed-rank test compared the D90 and V100 of the prostate and its sectors between methods.

RESULTS

The day 0 D90 and V100 for the prostate were 98% versus 94% and 88% versus 86% for CT-MRI fusion and MRI only dosimetry. There were no differences in the D90 or V100 of the whole prostate, mid-gland, or base between dosimetric methods (p > 0.19), but prostate apex D90 was high by 13% with MRI dosimetry (p = 0.034). The average distance between seeds on CT-MRI fusion and MRI alone was 5.5 mm. After additional automated rigid registration of 3D seed positions, the average distance between seeds was 0.3 mm, and the previously observed differences in apex dose between methods was eliminated (p > 0.11).

CONCLUSIONS

Permanent prostate brachytherapy dosimetry based only on MRI using positive contrast MRI markers is feasible, accurate, and reduces the uncertainties arising from CT-MRI fusion abating the need for postimplant multimodality imaging.

Permanent prostate brachytherapy pubic arch evaluation with diagnostic magnetic resonance imaging

PURPOSE

Pubic arch interference (PAI), when it occurs, is often a limiting factor for patients pursuing brachytherapy treatment of prostate cancer. Pre-brachytherapy pubic arch evaluation is often performed by CT or transrectal ultrasound (TRUS), but MRI has increasingly replaced these modalities for prostate cancer evaluation. The purpose of this study was to determine if staging MRI could be used to evaluate PAI and compare it with these other imaging methods.

METHODS AND MATERIALS

Forty-one consecutive patients undergoing brachytherapy evaluation had pelvic MRI-, CT-, and TRUS-based brachytherapy simulation. Pubic arch overlap on T2-weighted MRI and CT was determined by contouring the prostate gland on its largest axial slice and superimposing this contour onto the pubic arch bones. The largest degree of overlap of the prostate gland on MRI and CT was used to predict the existence of PAI as determined by TRUS-based simulation. The correlation between prostate contour overlap was also compared between MRI and CT.

RESULTS

Nineteen patients (48%) exhibited PAI on TRUS brachytherapy simulation evaluation. The average (±standard error) amount of prostate contour overlap on the pubic arch on CT was 2.9 ± 0.6 mm and on MRI was 2.0 ± 0.6 mm (linear correlation, R, of 0.783, p < 0.001). CT and MRI were equally predictive of PAI on TRUS evaluation (area under the curve = 0.75).

CONCLUSION

Pre-brachytherapy pubic arch assessment with diagnostic MRI provides similar predictability of PAI compared with CT, potentially obviating the need for additional pre-brachytherapy CT in the setting of staging MRI.

ACR appropriateness criteria: Permanent source brachytherapy for prostate cancer

PURPOSE

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

METHODS AND MATERIALS

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

RESULTS

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

CONCLUSIONS

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

Variability in MRI vs. ultrasound measures of prostate volume and its impact on treatment recommendations for favorable-risk prostate cancer patients: a case series

Background

Prostate volume can affect whether patients qualify for brachytherapy (desired size ≥20 mL and ≤60 mL) and/or active surveillance (desired PSA density ≤0.15 for very low risk disease). This study examines variability in prostate volume measurements depending on imaging modality used (ultrasound versus MRI) and volume calculation technique (contouring versus ellipsoid) and quantifies the impact of this variability on treatment recommendations for men with favorable-risk prostate cancer.

Methods

We examined 70 patients who presented consecutively for consideration of brachytherapy for favorable-risk prostate cancer who had volume estimates by three methods: contoured axial ultrasound slices, ultrasound ellipsoid (height × width × length × 0.523) calculation, and endorectal coil MRI (erMRI) ellipsoid calculation.

Results

Average gland size by the contoured ultrasound, ellipsoid ultrasound, and erMRI methods were 33.99, 37.16, and 39.62 mLs, respectively. All pairwise comparisons between methods were statistically significant (all p < 0.015). Of the 66 patients who volumetrically qualified for brachytherapy on ellipsoid ultrasound measures, 22 (33.33%) did not qualify on ellipsoid erMRI or contoured ultrasound measures. 38 patients (54.28%) had PSA density ≤0.15 ng/dl as calculated using ellipsoid ultrasound volumes, compared to 34 (48.57%) and 38 patients (54.28%) using contoured ultrasound and ellipsoid erMRI volumes, respectively.

Conclusions

The ultrasound ellipsoid and erMRI ellipsoid methods appeared to overestimate ultrasound contoured volume by an average of 9.34% and 16.57% respectively. 33.33% of those who qualified for brachytherapy based on ellipsoid ultrasound volume would be disqualified based on ultrasound contoured and/or erMRI ellipsoid volume. As treatment recommendations increasingly rely on estimates of prostate size, clinicians must consider method of volume estimation.

Large prostate gland size is not a contraindication to low-dose-rate brachytherapy for prostate adenocarcinoma

PURPOSE

Prostate volume greater than 50cc is traditionally a relative contraindication to prostate seed implantation (PSI), but there is little consensus regarding prostate size and clinical outcomes. We report biochemical control and toxicity after low-dose-rate PSI and compare outcomes according to the prostate size.

METHODS AND MATERIALS

A total of 429 men who underwent low-dose-rate PSI between 1998 and 2009 were evaluated. Median followup was 38.7 months. Patients were classified by prostate volume into small, medium, and large subgroups. Differences were analyzed using the Mann-Whitney and Pearson's χ(2) tests for continuous and categorical variables, respectively. Cox proportional hazards regression models were used to evaluate effect of prostate size on outcomes.

RESULTS

Patient pretreatment factors were balanced between groups except for age (p=0.001). The 10-year actuarial freedom from biochemical failure for all patients treated with PSI was 96.3% with no statistically significant difference between large vs. small/medium prostate size (90% vs. 96.6%, p=0.47). In a multivariate analysis, plan type (hazard ratio [HR]=0.25, p=0.03), dose to 90% of the gland (D90: HR=0.98, p=0.02), volume receiving 200Gy (V200: HR=0.98, p=0.026), and biologic effective dose (HR=0.99, p=0.045), but not prostate size (HR=2.27, p=0.17) were significantly associated with freedom from biochemical failure. Prostate size was not significantly associated with time to maximum American Urologic Association score.

CONCLUSION

In men with large prostates, the PSI provides biochemical control and temporal changes in genitourinary toxicity that are comparable with men having smaller glands. Accurate dose optimization and delivery of PSI provides the best clinical outcomes regardless of gland size.

Image-guided therapy system for interstitial gynecologic brachytherapy in a multimodality operating suite

In this contribution, an image-guided therapy system supporting gynecologic radiation therapy is introduced. The overall workflow of the presented system starts with the arrival of the patient and ends with follow-up examinations by imaging and a superimposed visualization of the modeled device from a PACS system. Thereby, the system covers all treatments stages (pre-, intra- and postoperative) and has been designed and constructed by a computer scientist with feedback from an interdisciplinary team of physicians and engineers. This integrated medical system enables dispatch of diagnostic images directly after acquisition to a processing workstation that has an on-board 3D Computer Aided Design model of a medical device. Thus, allowing precise identification of catheter location in the 3D imaging model which later provides rapid feedback to the clinician regarding device location. Moreover, the system enables the ability to perform patient-specific pre-implant evaluation by assessing the placement of interstitial needles prior to an intervention via virtual template matching with a diagnostic scan.

Predicting pubic arch interference in prostate brachytherapy on transrectal ultrasonography-computed tomography fusion images

We investigated the usefulness of the fusion image created by transrectal ultrasonography (TRUS) and large-bore computed tomography (CT) for predicting pubic arch interference (PAI) during prostate seed brachytherapy. The TRUS volume study was performed in 21 patients, followed by large-bore computed tomography of patients in the lithotomy position. Then, we created TRUS-CT fusion images using a radiation planning treatment system. TRUS images in which the prostate outline was the largest were overlaid on CT images with the narrowest pubic arch. PAI was estimated in the right and left arch separately and classified to three grades: no PAI, PAI positive within 5 mm and PAI of >5 mm. If the estimated PAI was more than 5 mm on at least one side of the arch, we judged there to be a significant PAI. Brachytherapy was performed in 18 patients who were evaluated as not having significant PAI on TRUS. Intra-operative PAI was observed in one case, which was also detected with a fusion image. On the other hand, intra-operative PAI was not observed in one case that had been evaluated as having significant PAI with a fusion image. In the remaining three patients, TRUS suggested the presence of significant PAI, which was also confirmed by a fusion image. Intra-operative PAI could be predicted by TRUS-CT fusion imaging, even when it was undetectable by TRUS. Although improvement of the reproducibility of the patients' position to avoid false-positive cases is warranted, TRUS-CT fusion imaging has the possibility that the uncertainty of TRUS can be supplemented.

Risk of all-cause and prostate cancer-specific mortality after brachytherapy in men with small prostate size

BACKGROUND

Brachytherapy for prostate cancer can be technically challenging in men with small prostates (≤20 cc), but it is unknown whether their outcomes are different than those of men with larger prostates.

METHODS AND MATERIALS

We studied 6,416 men treated with brachytherapy in one of 21 community-based practices. Cox regression and Fine and Gray's regression were used to determine whether volume ≤20 cc was associated with a higher risk of all-cause mortality (ACM) or prostate cancer-specific mortality (PCSM), respectively, after adjustment for other known prognostic factors.

RESULTS

443 patients (6.9%) had a prostate volume ≤20 cc. After a median follow-up of 2.91 years (interquartile range, 1.06-4.79), volume ≤20 cc was associated with a significantly higher risk of ACM (adjusted hazard ratio = 1.33 [95% CI 1.08-1.65], p = 0.0085) with 3-year estimates of ACM for ≤20 cc vs. >20 cc of 13.0% vs. 6.9% (p = 0.028). Only 23 men (0.36%) have died of prostate cancer, and no difference was seen in PCSM by volume (p = 0.4).

CONCLUSION

Men with small prostates at the time of implant had a 33% higher risk of ACM, and the underlying cause of this remains uncertain. No increase in PCSM was observed in men with volume ≤20cc, suggesting that a small prostate should not in itself be a contraindication for brachytherapy, but inasmuch as absolute rates of PCSM were small, further follow-up will be needed to confirm this finding.

High-dose-rate brachytherapy for large prostate volumes (> or =50cc)-Uncompromised dosimetric coverage and acceptable toxicity

PURPOSE

The purpose of this study was to review our single-institution experience using high-dose-rate (HDR) brachytherapy in patients with large-volume prostate glands (> or =50cc).

METHODS AND MATERIALS

Fifty-four patients treated with HDR brachytherapy for prostate cancer at the Penrose Cancer Center between 2001 and 2006 were identified as having an ultrasound volume of at least 50cc at the time of implant (range, 50-97.3cc; mean, 61.5cc; median, 57cc; upper quartile, 83.3-97.3cc). Neoadjuvant hormones (17 patients) were not routinely recommended unless the initial ultrasound volume suggested pubic arch interference or the patient's Gleason score or prostate specific antigen prompted use. All patients received HDR brachytherapy as a boost before or after conformal external beam radiation therapy to 4500cGy. Boost brachytherapy doses ranged from 1600 to 1900cGy, given in two to three fractions.

RESULTS

The median D(90) (minimal dose to 90% of the prostate) was 109% of prescription dose (range, 95-115%) and the median V(100) (volume receiving 100% of the dose) was 96% (range, 90-99%). V(150) ranged from 10% to 35%, with a median value of 18.3%. Six patients (11%) required temporary placement of a urinary catheter for acute obstructive symptoms after brachytherapy. With a median followup of 1.8 years, there has been a single case of Grade 2 gastrointestinal toxicity and 1 patient has developed a bulbo-urethral stricture requiring dilation. There have been no cases of rectal bleeding.

CONCLUSIONS

Large prostate volume is not a contraindication to HDR brachytherapy. Excellent dosimetric coverage can be attained with acceptable acute toxicity.

Dynamic dose-feedback prostate brachytherapy in patients with large prostates and/or planned transurethral surgery before implantation

OBJECTIVE

To compare the quality of permanent prostate brachytherapy (PPB) implants, dosimetric outcomes and urinary morbidity between patients with large (>50 mL) and those with smaller prostates, treated with a dynamic dose-feedback technique as monotherapy for localized prostate cancer.

PATIENTS AND METHODS

The series included patients with pre-existing bladder outlet obstruction managed with planned transurethral resection or incision of the prostate; 155 consecutive men had PPB implants as monotherapy for localized prostate cancer using a dynamic dose-feedback approach. Dosimetric variables assessed included the implant volume, the minimum dose to 90% of the prostate (D90), and the volumes of prostate receiving 100% and 150% of the prescribed dose as a percentage of the total volume (V100 and V150), during and after implantation. Urinary morbidity was recorded in terms of acute urinary retention (AUR), the need for surgical intervention after implantation and the American Urologic Association (AUA) symptom score at baseline, 1.5, 3, 6, 9, 12 and 18 months.

RESULTS

In all, 38 patients had prostate volumes of >or=50 mL; prostate volume had no influence on any dosimetric variable assessed. Two patients with large prostates (>or=50 mL) had AUR and required delayed surgery. Three patients with small prostates (<50 mL) had transient retention; the differences were not statistically significant (Fisher's exact test). AUA symptom scores peaked at 6 weeks and returned to baseline within a year; there were no statistically significant differences between the groups. Eight patients had planned transurethral surgery at >or=4 months before implantation; they all had D90s of >130 Gy and had no incontinence.

CONCLUSION

Using the dynamic feedback technique, there was no adverse dosimetric and urinary morbidity in men having PPB and with prostates of >50 mL. Likewise, there were no impediments, e.g. pubic arch interference, which precluded a favourable dosimetric implant in men with a large prostate. Large prostates should not be a contraindication to PPB and require no hormonal cytoreduction. Patients with obstructive lower urinary tract symptoms can be managed with planned transurethral prostatic surgery before implantation, without compromising implant quality or morbidity.

The impact of prostate volume following neoadjuvant androgen deprivation on quality of life and voiding symptoms in patients undergoing permanent prostate brachytherapy

OBJECTIVE

Patients with large prostate volumes undergoing interstitial brachytherapy (BT) are currently believed to have worse urinary symptoms and quality of life (QOL) following the implant. We sought to determine if data from patients treated with neoadjuvant androgen ablation followed by BT at our institution supported this notion using a cross-sectional study design.

METHODS

From 14 March 1997 to 25 August 2000, 248 patients underwent neoadjuvant androgen ablation followed by BT monotherapy (BTM) or BT combined with external beam (BTC) for treatment of localized prostate cancer. FACT-G and AUASS questionnaires were mailed to all patients on 1 September 2001. Overall FACT-G scores along with the irritative (IAUA) and obstructive (OAUA) subscales of the AUASS were calculated for each patient. Prostate volume (one to two weeks prior to BT), number of seeds, and implant method (ultrasound or CT guided) were compared with the outcomes on the two validated instruments. All analyses were adjusted for time since procedure and patient age.

RESULTS

169 of 248 (68%) patients returned questionnaires. The median prostate volume was 37cc and number of seeds implanted was 95. Our data shows little correlation between total FACT-G or AUASS scores and volume of the prostate. Likewise, neither FACT-G nor IAUA scores appeared related to the number of seeds implanted. A correlation was seen when comparing number of seeds with OAUA scores, but this result appeared to be driven by the BTC group. Number of needles implanted did not appear to be related to total FACT-G scores. The number of needles inserted was related to both IAUA and OAUA scores in the BTC group, but not in BTM group.

CONCLUSION

Quality of life and urinary function scores do not appear to be strongly related to pre-implant prostate volume or method of implantation and thus patients should not be dissuaded from considering neoadjuvant androgen ablation followed by BT solely due to prostate size.

Localized prostate cancer: brachytherapy

Brachytherapy is a treatment for localized prostate cancer that has become popular with physicians and patients. The use and convenience of transrectal ultrasound and transperineal placement of the sources make contemporary forms of this procedure more accurate and more patient-friendly than their predecessors. In addition, the early detection of cancer by the use of prostate-specific antigen (PSA) makes contemporary tumors more amenable to successful treatment by such a localized technique. Brachytherapy offers cancer control rates at 5 years, as measured by PSA, that seem to be as effective as surgery and external beam therapy. Less information is available for 10 years, and none afterward. The acute urinary morbidity rate of brachytherapy is higher than for external beam therapy, but the late urinary morbidity rate is probably equal. The rectal morbidity rate is less. The risk of erectile impotence is uncertain but not as low as originally hoped. The use of external radiation in combination with brachytherapy may increase 5-year tumor control rates but is substantially more expensive and likely carries an increased risk of morbidity. Newer forms of brachytherapy such as magnetic resonance-guided and high-dose-rate temporary implants have vocal advocates but a shorter track record and fewer published prospective studies. Their use remains investigational. Therefore, prostate brachytherapy remains a reasonable option for men with early stage disease, but there remain unanswered questions regarding long-term efficacy and morbidity.

Long-term urinary function after transperineal brachytherapy for patients with large prostate glands

PURPOSE

To summarize longer-term postbrachytherapy morbidity in patients with prostate glands >50 cm3.

METHODS AND MATERIALS

From 1997 to 1998, 33 patients with a transrectal ultrasound-based prostate volume >50 cm3 were treated at the University of Washington by 125I (144 Gy) or 103Pd (115 Gy) implantation for prostate carcinoma. These 33 patients comprised 7% of the total implant patient population. Twelve patients were treated with neoadjuvant androgen ablation before implantation. The (125)I source strength ranged from 0.34 to 0.5 mCi and the 103Pd source strength ranged from 1.1 to 1.4 mCi (pre-NIST-99). The total number of sources implanted was 94-223 (median 155). Despite the typical implant-related volume increase, the postimplant CT-defined prostate volumes were generally well-covered by the prescription isodose (median coverage 92%, range 80-100%). The preimplant urinary obstructive symptoms were quantified by the criteria of the American Urological Association.

RESULTS

Of the 33 patients, 12 developed acute postimplant urinary retention, all presenting within 24 h of implantation. Patients who developed postimplant retention lasting >1 week were generally treated with intermittent self-catheterization. By 1 month, 85% of patients were catheter free. By 1 year, only 1 patient (4%) remained in urinary retention; the remainder of cases had resolved spontaneously. With follow-up of 1.7-2.6 years, the last American Urological Association scores were higher than the pretreatment scores in 15 patients and lower in 7 patients. No patient developed permanent urinary incontinence. Long-term changes in the American Urological Association scores were unrelated to whether the patient had been in urinary retention after implantation. Two patients developed rectal fistulas; they had preimplant transrectal ultrasound prostate volumes of 53 and 59 cm3, in the low range for this group of patients. No other patient had persistent rectal bleeding suggestive of clinically significant proctitis. The pretreatment serum prostate-specific antigen level was 3.3-15 ng/mL (median 7.2) and the last serum prostate-specific antigen level 0.1-1.6 ng/mL (median 0.2).

CONCLUSION

Patients with larger prostate volumes appear to have moderate morbidity and a satisfactory technical outcome with brachytherapy. We do not believe the occurrence of two severe rectal complications was related to the prostate volume per se. Our experience and that of others calls into question the validity of using prostate volume as a criterion for patient suitability for prostate brachytherapy.

Real-time optimized intraoperative dosimetry for prostate brachytherapy: a pilot study

PURPOSE

To assess the feasibility of real-time intraoperative treatment planning for permanent prostate brachytherapy analyzing the impact on operative time and adequacy of postimplant dosimetry.

METHODS AND MATERIALS

Seventeen consecutive patients undergoing permanent brachytherapy for prostate cancer had real-time intraoperative computer-based and optimized treatment planning. The first 8 patients were implanted using a plan generated before the surgery and served to assure the team qualitatively that this could be performed without greatly increasing intraoperative time. They served as control group for expected achieved dosimetry results reviewing the D90, V100, V150 parameters from the dose-volume histograms. The next 9 patients were implanted according to the real-time plan. The times needed to carry out various steps of the procedure were recorded. The achieved dosimetry was then compared to the control group to assure that accuracy was unchanged.

RESULTS

The median operative time for patients undergoing intraoperative dosimetry was 57 min. Of this, 21 min were devoted to anesthesia and nursing functions. Postoperative dosimetry showed a median achieved V100 (volume of prostate receiving 100% of prescribed dose) of 97% for the control group. For the real-time dosimetry group, the median V100 was similar at 94%. The V150 (volume receiving 150%) is 49% for both groups. The D90 (dose received by 90% of the target) was normalized for easy comparison and was consistently slightly greater than the prescription dose.

CONCLUSION

Treatment planning for permanent brachytherapy of prostate cancer has historically been performed as a computer-generated and optimized plan run weeks in advance of an implant, or according to a set pattern using an intraoperative nomogram. These data show that planning can now be optimized intraoperatively using widely available software without compromising the operative time or implant quality.

Effects of pelvic rotation and needle angle on pubic arch interference during transperineal prostate implants

PURPOSE

Pubic arch interference due to an enlarged prostate gland or a narrow pubic arch is often a limiting factor in adequate prostate coverage during transperineal brachytherapy. The purpose of this study was to evaluate the effects of both pelvic rotation and needle angles on pubic arch interference using CT-based 3-D information.

METHODS AND MATERIALS

Seven patients had CT imaging in both supine and lithotomy positions and 3-D treatment planning was performed with three needle angles (20 downward, 0, 20 upward). The pubic arch interference was then measured and comparisons were made for each needle trajectory and pelvic position.

RESULTS

Increasing pelvic rotation from supine to lithotomy position shows less pubic arch interference. Directing the needle tip upward shows less pubic arch interference in both supine and lithotomy positions when compared to needle tips directed downward.

CONCLUSIONS

Both pelvic position and needle angles are important factors influencing pubic arch interference. Preplanning CT-based 3-D information may assist for individualized treatment planning in patients with a significant bony interference, thus avoiding pubic arch interference during implantation.

Prostate brachytherapy in patients with prostate volumes >/= 50 cm(3): dosimetic analysis of implant quality

OBJECTIVES

Permanent implantation with (125)I in patients with localized prostate cancer who have prostate volumes >/= 50 cm(3) is often technically difficult owing to pubic arch interference. The objective of this study was to describe dosimetry outcomes in a group of patients who were implanted using the real-time ultrasound-guided technique who had prostate volumes >/= 50 cm(3).

MATERIALS AND METHODS

A total of 331 patients received an (125)I prostate seed implant from January 1, 1995, to June 1, 1999, of whom 66 (20%) had prostate volumes >/= 50 cm(3) at the time of the procedure. The real-time seed implant method was used in all patients and consisted of intraoperative planning and real-time seed placement using a combination of axial and sagittal ultrasound imaging. Pubic arch interference was managed using an extended lithotomy position or by angling the tip of the ultrasound probe in an anterior direction. No preimplant pubic arch CT scan study was performed and no patients were excluded from treatment because of prostate size. Implant quality was assessed using CT-based dosimetry performed 1 month postimplant. Dose-volume histograms for the prostate, bladder, rectum, and urethra volumes were generated. The target dose for these implants was 160 Gy and an adequate implant was defined as the dose delivered to 90% of the prostate (D90) >/= 140 Gy. The dose delivered to 95% of the prostate (D95) and doses to 30% of the rectal (DRECT30) and urethral (DURE30) volumes were also calculated.

RESULTS

Prostate volumes in the 66 patients ranged from 50 to 93 cm(3) (median 57, mean 61 cm(3)). Total activity implanted was 27.8-89.1 mCi (median 57 mCi), with a range in activity per seed of 0.36-0.56 mCi (median 0.4 mCi). The prostate D90s and D95s ranged from 13,245 to 22,637 cGy (median 18,750) and 11,856 to 20,853 cGy (median 16,725), respectively. Only one patient (1.5%) had a D90 < 140 Gy. The DURE30 values ranged from 15,014 to 27,800 cGy (median 20,410) and the DRECT30 values were 3137-9910 cGy (median 5515).

CONCLUSION

Implantation of the large prostate can be accomplished using the real-time method. A total of 98.5% of the patients receive a high-quality implant. In addition, these implants should not put patients at increased risk for significant urinary and bowel complications because urethral and rectal doses can be kept at acceptable levels.

Examining the role of neoadjuvant androgen deprivation in patients undergoing prostate brachytherapy

PURPOSE

To assess the role of neoadjuvant androgen deprivation (NAAD) and transperineal interstitial permanent prostate brachytherapy (TIPPB) using a matched-pair analysis selected from a large cohort of patients undergoing TIPPB.

PATIENTS AND METHODS

Six hundred twelve consecutive patients with clinically confined prostate cancer were treated between June 1992, and January 1997, with permanent ultrasound-guided TIPPB with either palladium-103 or iodine-125 as monotherapy or combined with external radiation. Patients with prostate glands >/= 60 g underwent treatment with NAAD before TIPPB to reduce the prostate volume (n = 163). The median duration of NAAD was 3.4 months before TIPPB (range, 1 to 8 months). To assess the benefit of NAAD, a matched-pair analysis was performed. The American Society of Therapeutic Radiology and Oncology Consensus Group definition of prostate-specific antigen (PSA) relapse-free survival (RFS) was used with the added caveat of an absolute increase of >/= 1.0 ng/mL. Differences in pretreatment PSA, Gleason scores, and stage were analyzed by Kaplan-Meier curves and the log-rank test.

RESULTS

Two hundred sixty-three patients were matched, with a median follow-up duration of 46 months (range, 24 to 76 months). The actuarial 5-year PSA-RFS rate for all 263 patients is 86.5%. The 5-year PSA-RFS rate for patients treated with NAAD and TIPPB was 87.1% compared with 86.9% for those treated with TIPPB only (P =.935). Subgroup analysis by Gleason score groupings, pretreatment PSA, or stage of disease failed to identify any factors for which androgen ablation was beneficial.

CONCLUSION

We were unable to identify any improvement with the addition of NAAD to TIPPB in patients with localized prostate cancer in this retrospective matched-pair analysis. Furthermore, there was no subset for which the addition of NAAD was found to be beneficial. Clarification of the role and duration of NAAD in patients with early-stage prostate cancer will require prospective data.

Use of TRUS to predict pubic arch interference of prostate brachytherapy

PURPOSE

To demonstrate the potential for transrectal ultrasound (TRUS) to predict pubic arch interference of transperineal needle placement for prostate brachytherapy.

METHODS AND MATERIALS

TRUS and pelvic computerized tomography (CT) scans from 22 patients who had transperineal prostate brachytherapy at University of Washington were analyzed for pubic arch visualization and interference. The outer margins of the prostate and the inner margins of the pubic bones from each imaging modality were outlined and compared.

RESULTS

The pubic arch was readily visualized by TRUS in 21 of the 22 patients. There was good correlation between TRUS and CT for evaluating the amount of pubic arch interference (r = 0.90).

CONCLUSION

TRUS can be substituted for CT imaging to evaluate pubic arch interference of transperineal needle placement for prostate brachytherapy. Eliminating routine CT scanning would reduce the cost of treatment.

Comparability of CT-based and TRUS-based prostate volumes

PURPOSE

To compare the prostate volumes defined by transrectal ultrasound (TRUS) versus computed tomographic (CT) scans used for brachytherapy planning.

METHODS AND MATERIALS

Ten unselected patients underwent evaluation for prostate brachytherapy with TRUS and CT imaging. Axial prostate contours were obtained at 5-mm intervals in both studies. The CT images were photographed, scanned into a commercial software program, and reprinted from a laser printer at 600 dots per inch to provide individual images that were interpreted independently by the three physician authors (BK, KW, and JB). An effort was made to exclude pelvic floor muscles from the defined prostate contour. Volumes were calculated in cubic centimeters. The prostate volume and maximum dimension in each plane were compared for each imaging modality.

RESULTS

The CT-based prostate volumes ranged from 31.1 cc to 48.1 cc. The TRUS-based volumes ranged from 26.6 cc to 46.4 cc. There was close agreement between imaging modalities (r = 0.9). The anterior-posterior, lateral, and craniocaudal prostatic dimensions were similar between modalities. To test for consistency between observers, the CT volumes were drawn independently by KB, KW, and JB. The prostatic measurements were consistent in all dimensions between observers.

CONCLUSION

CT scan volumes and measurements correlate well with those obtained by TRUS, and are appropriate for pre- or postimplant dosimetry.