Combining Multi-Modality Imaging and Transperineal

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Abstracts / Brachytherapy 13 (2014) S15eS126 1

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Valdir Colussi, PhD , Robert Vinkler, RTT , April Deters, RTT1, Mitchell Machtay, MD1, Rodney J. Ellis, MD1. 1Radiation Oncology, University Hospitals Seidman Cancer Center, Cleveland, OH; 2Urology, University Hospitals Case Medical Center, Cleveland, OH. Purpose: To evaluate sexual health outcomes following interstitial brachytherapy seed implant with and without external beam radiation therapy (EBRT) in sexually active men treated for localized prostate cancer using molecular image-guided radiation therapy. Materials and Methods: We retrospectively reviewed prostate brachytherapy patients treated from 12/1999 to 12/2002 at a single institution by a single treating physician (RJE). The current study represents subset analysis of previously published 10-year actuarial prospective outcomes in 239 consecutive patients treated by prostate seed implant (PSI) with or without EBRT using molecular image guided treatment planning. PSI prescription doses were either 145/110 Gy (Iodine-125) or 125/100 Gy (Palladium-103) for PSI-alone/(PSIþEBRT). A typical peripheral loading treatment technique was used, with dose escalation to regions of the prostate identified as having focal uptake of Indium-111 labeled prostate specific membrane antigen (capromab pendetide) on SPECT/CT scans. Dose escalation (more than 150% of prescribed dose) was achieved by placing additional seeds during PSI. Minimal margins were contoured at prostate regions showing no involvement on SPECT/CT (e.g. uninvolved tissue surrounding the neurovascular bundles). In patients receiving neoadjuvant hormone ablation therapy, treatment began prior to PSI (typical range 1-6 months). We now analyze late toxicity outcomes for patients having completed sexual health inventory for men (SHIM) questionnaires at baseline (limited to only those reporting to be sexually active pretreatment) and having late post treatment SHIM followup. Retrospective data collection was performed by electronic and/or paper chart review with IRB approval. We classified erectile dysfunction (ED) by SHIM range: SHIM #7 (Severe ED), SHIM 9-21 (Moderate to Mild ED) versus SHIMO21 (No ED). Results: We identified 40 patients (16.7%) from the larger series with SHIM reported at baseline and having late followup, with median followup of 52.2 months (range 35.5-150.5). Presenting characteristics for this subset analysis included clinical stage (T1c-T3a, Nx, M0); PSA $10 (n55, 12.5%) and !10 (n535, 87.5%); Gleason sum #6 (n524, 60%), 7 (n515, 37.5%) and $8 (n51, 2.5%); median age 62.1 years (range 41.575.1); National Comprehensive Care NetworkÒ risk category low(n520, 50%), intermediate- (n515, 37.5%) and high-risk (n55 12.5%) group stratification. Twenty-five patients were treated by PSI-alone and 15 with PSIþEBRT. The number (n, %) patients reporting SHIM symptoms before therapy at baseline by SHIM category were: Severe ED (1, 2.5%), Moderate to Mild ED (4, 10%) versus No ED (35, 87.5%). For the 35 patients reporting No ED at baseline, 12 (34.3%) went on to report Severe ED, 12 (34.3%) Moderate to Mild ED and 11 (31.4%) reported No ED at last SHIM followup. For the 4 patients reporting Moderate to Mild ED at baseline, 2 reported Severe ED, 1 Mild to Moderate ED and 1 No ED at the time of last followup. There was no change in SHIM score for the single patient reporting Severe ED pretreatment. Older age at last SHIM report was found directly related to the incidence of ED symptoms. Conclusions: Late toxicity assessment found that sexual function was maintained in a third of patients reporting no erectile dysfunction prior to radiation therapy for primary treatment of localized prostate cancer using advanced imaging to plan treatment. Molecular image guided dose escalation may be useful in conformal therapies for men seeking to minimize treatment related morbidity and preserve sexual function. Additional studies are warranted to further evaluate the use of functional imaging in prostate cancer management.

PO81 Combining Multi-Modality Imaging and Transperineal Mapping Biopsy to Guide the Focal Application of Low-Dose-Rate Brachytherapy for Prostate Cancer: An Ethics Approved Pilot Study S. Sara Mahdavi, PhD1, W. James Morris, FRCPC1, Septimiu E. Salcudean, PhD2, Silvia D. Chang, MD3, Piotr Kozlowski, PhD2, Ingrid T.

Spadinger, PhD1. 1BCCA - Vancouver Center, Vancouver, BC, Canada; 2 University of British Columbia, Vancouver, BC, Canada; 3Vancouver General Hospital, Vancouver, BC, Canada. Purpose: Whole-gland treatment for prostate cancer, be it radical prostatectomy or radiation therapy, adversely affects quality of life, particularly in the sexual and urinary-function domains. The only accepted alternative for favorable risk cancers is active surveillance (AS). However, an evidence-based consensus defining disease progression and the need for timely radical therapy is lacking. Other drawbacks of AS include the infection risk associated with multiple trans-rectal biopsies and the psychological stress an untreated cancer may provoke, given the unpredictable nature of the disease. Recent technical advances have stimulated research into focal therapy (FT), a potential third alternative for appropriately selected patients. However, the widespread adoption of FT is held back by two major limitations: Firstly, standard trans-rectal biopsy is unsuitable for directing focal therapy due to suboptimal sampling and a lack of precision guidance. Secondly, due to substantial sparing of healthy prostate tissue, post-treatment PSA values are no longer reliable for validating treatment efficacy. This work is aimed at overcoming the first of these limitations with the ultimate goal of establishing FT based on low-dose-rate brachytherapy (LDRB) as an option for selected men with favorable risk disease. In this pilot study we plan to: 1) explore the correlations between prostate cancer, as mapped by TTMB (see below), and multi-modal imaging. 2) determine if FT has less impact on QOL than whole-gland LDRB. Materials and Methods: Eligibility criteria at entry include Gleason score #3þ4 in any one core, #2 cores positive from one lobe, clinical stage #T2a, and iPSA #10ng/mL. Consented participants initially undergo imaging including C11-Choline PET/CT, a 3-Tesla, multiparametric (mp) MRI (T2W, DWI, DCE), MR elastography (MRE), and trans-rectal ultrasound elastography (TRUS-E). After imaging, a transperineal template mapping biopsy (TTMB) is performed with the subject under general or spinal anaesthesia. TTMB combines a custom template with TRUS image guidance. The pitch of TTMB cores is specified to allow the creation of a 3D cancer map with a probability of !0.05 of missing a tumor of $8 mm across (assuming a spherical shape). Subjects in which TTMB yields #4 positive cores (each with GS #3þ4) within a single lobe and spanning not more than two adjacent sectors (apex, mid-gland and base), will be offered FT in addition to the option of continuing on AS or selecting one of the conventional radical treatments. For patients electing FT, the planning target volume (PTV) is considered as the location of every positive core with a radius equal to the biopsy pitch and the height determined by the prevalence of cancer throughout the core, to which a 5mm margin is

Figure 1. Schematic of the focal LDR brachytherapy procedure. Upon eligibility the patient proceeds to multi-parametric MRI (mpMRI), MR elastography (MRE) and PET/CT. If eligible, in one session, trans-rectal ultrasound (TRUS), TRUS elastography (TRUS-E) and transperineal 3D template guided pathological mapping biopsy (TTMB) will be performed. If focal therapy is chosen, a treatment plan will be created based on TTMB results and after treatment, follow-up will proceed as indicated.

Abstracts / Brachytherapy 13 (2014) S15eS126 added. The prescription minimum peripheral dose to the PTV is 144Gy. Followup includes physical examination, PSA, and patient-reported QoL/IPSS/SHIM at 6 weeks and q3 monthly to 2 years and every 6 months thereafter. The PET/CT, mpMRI, MRE, and TRUS-E are repeated at 12 and 24 months. A second TTMB to confirm tumor ablation and rule out new tumor foci is scheduled for 24 months. The TTMB results will be registered and correlated to initial and repeated mpMRI, MRE, and TRUS-E to assess the clinical validity of imaging methods in detecting cancer prior to treatment and the presence of residual/recurrent cancer post-treatment. Results: This pilot study will accrue 10 patients over one year. The study opened in September 2013 and six subjects are presently enrolled. Preliminary data on imaging and TTMB correlations will be presented. Conclusions: LDRB is a reasonable candidate for focal therapy and is being conducted in the context of an ethics-approved trial.

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V90%) was 0.5% or less, any increase of rectal V80% was 0.08cc or less and any increase in urethra D10% was 1.5% or less. Two patients required different optimization parameters compared to what was used in the clinical plan in order to reduce dose to the rectum, which is thought to be due to the location of the catheters that were excluded. Using a larger threshold for excluding catheters resulted in larger dosimetric changes to these plans. Frequency of use for each grid position is evaluated excluding the underutilized catheters for all patients and in each size range. These plots can be used to establish guidelines to help physicians in selecting the most efficient catheter placement depending on prostate volume. Conclusions: We show template grid position trends for 86 patients treated to date at our center. Re-optimization of treatment plans for 15 patients with a range of prostate volumes showed very little change when catheters contributing less than 1% were excluded. This information can potentially guide physicians during HDR procedures in selecting appropriate catheter positions.

PO82 Developing Volume Based Catheter Placement Guidelines for RealTime High-Dose-Rate Prostate Brachytherapy Aaron Vandermeer, PhD1, Wayne Koll, MD2, Audrey Li, MD2, Erik Mason, Student1, Jimmy Mui, MD2, Cathy Neath, MSc1, Daxa Patel, MSc1. 1 Medical Physics, Durham Regional Cancer Centre, Oshawa, ON, Canada; 2Radiation Oncology, Durham Regional Cancer Centre, Oshawa, ON, Canada. Purpose: For high-dose-rate (HDR) prostate brachytherapy, catheter positions are limited according to a template grid. Selecting number of catheters and their location in this grid is dependent on multiple parameters such as prostate shape and size, urethra and public arch location, and the shadowing effect of the catheters in ultrasound images used for treatment planning. Using the minimum number of catheters required to achieve adequate coverage decreases needle trauma and prostate swelling, can reduce the shadowing effect in ultrasound images and can decrease the planning and treatment time. We present trends of location and utilization of catheters in the plans of 86 HDR prostate patients treated at the Durham Regional Cancer Centre, evaluated with the purpose of developing departmental guidelines for the number and location of catheters to be used. Materials and Methods: During the HDR procedures the BK Flexfocus ultrasound unit was used to obtain real time transverse and sagittal images of the prostate. The physician selects the position of the catheters required to cover all regions of the prostate following the Nucletron template grid. After insertion, catheters are reconstructed on ultrasound images and Single Objective Dose Volume Histogram Optimization is used in the Oncentra Prostate (v3.3) treatment planning system to determine the dwell times in each catheter. Dwell position activation and times are determined by department specific activation rules and optimization parameters. Results: The catheter grid positions in the needle template and total dwell time in each catheter were recorded for all patients. For 8%, 68% and 18% of patients 17, 16 and 15 catheters were used, respectively. The attached figure shows frequency of use for each catheter grid position and statistics describing number of catheters used in each row for all patients. This is repeated with patients grouped into small (!30cc), medium (30-50cc) and large (O50cc) prostate volumes as determined from the treatment plans. The relative utilization of each grid position in the treatment plan was determined by plotting the average dwell time of each position (scaled to a 10 Ci source) for allpatients and for patients in each size group. To investigate the potential reduction of number of catheters required, catheters with low treatment times were identified for each patient. It was found that 44% had 1 or more catheters that were underutilized, contributing less than 1% to the total treatment time. A sample of 5 patients from each prostate size group was replanned with underutilized catheters excluded to evaluate the impact on plan quality. After optimization any decrease of the prostate coverage (V100% and

PO83 Dosimetric and Clinical Implications of Prostate Volume in Patients Managed with Low-Dose-Rate Interstitial Brachytherapy Rebekah Maymani, MD, Imad Ali, PhD, Spencer Thompson, MD, Salahuddin Ahmad, PhD, Ozer Algan, MD. Radiation Oncology, Oklahoma University Health Sciences Center, Oklahoma City, OK. Purpose: Prostate volume is often assessed in patients under consideration for permanent low-dose-rate (LDR) interstitial brachytherapy to address anatomic concerns or ensure sufficient seed activity. With intraoperative planning and post-implantation analysis, volume is again measured although in different clinical settings and with different modalities. The present study reviews the impact of intraoperative prostate volume on intraoperative and day 30 dosimetric parameters as well as gastrointestinal (GI) and genitourinary (GU) toxicity. Toxicities are reported as they relate to intraoperative and post-implantation parameters. Materials and Methods: A retrospective review of 83 low- and intermediate-risk prostate cancer patients managed with LDR interstitial brachytherapy as monotherapy or boost from 2008-2013 was performed. All patients had intraoperative planning and post-implantation dosimetric Table 1 Correlation Between Intraoperative Prostate Volume and Post-Implantation Dosimetric Parameters Dosimetric Parameter

Pearson Correlation Coefficient

p-value

V200 V150 V100 V90 V80 D100 D90 D80 D50 Maximum Dose Minimum Dose Mean Dose

0.315 0.332 0.333 0.326 0.327 0.363 0.417 0.380 0.340 0.234 0.339 0.294

0.004 0.002 0.002 0.003 0.003 0.001 !0.001 !0.001 0.002 0.032 0.002 0.007