Deep-learning-assisted algorithm for catheter reconstruction during MR-only gynecological interstitial brachytherapy.

Magnetic resonance imaging (MRI) offers excellent soft-tissue contrast enabling the contouring of targets and organs at risk during gynecological interstitial brachytherapy procedure. Despite its advantage, one of the main obstacles preventing a transition to an MRI-only workflow is that implanted plastic catheters are not reliably visualized on MR images. This study aims to evaluate the feasibility of a deep-learning-based algorithm for semiautomatic reconstruction of interstitial catheters during an MR-only workflow. MR images of 20 gynecological patients were used in this study. Note that 360 catheters were reconstructed using T1- and T2-weighted images by five experienced brachytherapy planners. The mean of the five reconstructed paths were used for training (257 catheters), validation (15 catheters), and testing/evaluation (88 catheters). To automatically identify and localize the catheters, a two-dimensional (2D) U-net algorithm was used to find their approximate location in each image slice. Once localized, thresholding was applied to those regions to find the extrema, as catheters appear as bright and dark regions in T1- and T2-weighted images, respectively. The localized dwell positions of the proposed algorithm were compared to the ground truth reconstruction. Reconstruction time was also evaluated. A total of 34 009 catheter dwell positions were evaluated between the algorithm and all planners to estimate the reconstruction variability. The average variation was 0.97 ± 0.66 mm. The average reconstruction time for this approach was 11 ± 1 min, compared with 46 ± 10 min for the expert planners. This study suggests that the proposed deep learning, MR-based framework has potential to replace the conventional manual catheter reconstruction. The adoption of this approach in the brachytherapy workflow is expected to improve treatment efficiency while reducing planning time, resources, and human errors.

Budget Impact Analysis of Preoperative Radioactive Seed Localization.

BACKGROUND: This study models costs in implementing a radioactive seed localization (RSL) program for nonpalpable breast lesions at a large Canadian tertiary hospital to replace existing wire-guided localization (WGL). METHODS: All direct and indirect operating costs of localization per lesion from the hospital's perspective were determined by retrospectively reviewing patient data and costs from January 2014 to December 2016. A budget impact analysis and sensitivity analysis were performed to calculate the mean cost per lesion, the minimum and maximum cost per lesion, operational costs, and initial costs. RESULTS: There were 265 WGL lesions in 2014 and 170 RSL lesions in 2016 included in cost calculation. The mean cost per localization was $185 CAD for WGL ($148-$311) and $283 CAD ($245-$517) for RSL using preloaded seeds, adjusted to 2016 Canadian dollars. The annual operational expenditure including all localizations and overhead costs was $49,835 for WGL and $80,803 for RSL. Initial costs for RSL were $22,000, including external training and new equipment purchases. CONCLUSIONS: Our budget impact analysis shows that RSL using preloaded radioactive seeds was more expensive than WGL when considering per-lesion localization costs and specific costs related to radiation safety. Manually loading radioactive seed could be a cost-saving alternative to purchasing preloaded seeds. Our breakdown of costs can provide a framework for other centres to determine which localization method best suit their departments.

Routine Breast Cancer Screening in Average-Risk Women Younger Than 50 Years: Current Paradigms Based on National Guidelines.

Breast cancer poses a large health care burden. More than 270,000 women are diagnosed with breast cancer every year in the United States alone, and more than 40,000 women will die from the disease over the same period. Advances in routine screening and curative treatment options have led to mean 5-year survival rates for localized and regional disease of 98.9% and 85.7%, respectively. Diagnosis at an early stage, often due to routine screening, represents one of the most important prognostic factors for survival. Routine mammography screening in average-risk women 50 years and older has reduced the age-adjusted mortality rate from breast cancer by 34% just over the past 20 years.2,3 While there is consensus among national health organizations regarding the benefits of routine mammographic screening in women 50 years and older, screening recommendations for average-risk women aged between 40 and 49 years vary. Differences in screening recommendations among national organizations largely reflect variations in assessment of the benefit-to-harm ratio of screening women aged between 40 and 49 years who are less likely to develop breast cancer, compared with older women. Women who do develop breast cancer in this age group, however, are more likely to develop more aggressive disease.4,5 Over the past decade, this has become an increasingly important topic of discussion as breast cancer shifts to a younger age of onset.1 In this review, we examine the risks and benefits of routine breast cancer screening starting at age 40 at the individual level, followed by an evaluation of the role of advanced imaging techniques in screening women on a population level.

Results of a phase I, non-randomized study evaluating a Magnetic Occult Lesion Localization Instrument (MOLLI) for excision of non-palpable breast lesions.

PURPOSE: Magnetic Occult Lesion Localization Instrument (MOLLI) is a wireless, non-radioactive alternative for non-palpable breast lesion localization. The primary objective of this first-in-human study was to evaluate the clinical feasibility of using MOLLI for intraoperative localization of non-palpable breast lesions. METHODS: Twenty women with non-palpable breast lesions at a single institution received a lumpectomy using the MOLLI guidance system. Patients were co-localized with magnetic and radioactive markers up to 7 days before excision by a dedicated breast radiologist under sonographic guidance. Both markers were localized intraoperatively using dedicated hand-held probes. The primary outcome was successful excision of the magnetic marker, confirmed radiographically and pathologically. Demographic data, margin positivity, and re-excision rates were collected. Surgical oncologists, radiologists, and pathology staff were surveyed for user satisfaction. RESULTS: Post-radiological analysis: Post-implant mammograms verified that 17/20 markers were placed directly in the lesion center. Radiologists reported that all marker implantations procedures were "easy" or "very easy" following a single training session. Post-surgical analysis: All MOLLI markers were successfully removed with the specimen during surgical excision. In all cases, surgeons ranked the MOLLI guidance system as "very easy" for lesion localization. Pathologic analysis: All patients had negative margins. All anatomic pathology staff ranked the MOLLI system as "very easy" to localize markers. CONCLUSIONS: The MOLLI guidance system is a reliable and accurate method for intraoperative localization of non-palpable breast lesions. Further evaluation of the MOLLI system in studies against current standards of care is required to demonstrate system cost-effectiveness and improved patient-reported outcomes.

Dosimetric impact of tracheostomy devices in head and neck cancer patients.

INTRODUCTION: The tracheostomy site and adjacent skin is at risk for recurrence in head/neck squamous cell cancer patients. The tracheostomy tube is an in situ device located directly over the tracheostomy site and may have clinical implications on the radiation dose delivered to the peristomal region. This study aimed to investigate this effect by comparing the prescribed treatment planning dose with the actual dose in vivo to the peristomal clinical target region. A retrospective, dosimetric study was performed with approval of the institutional research ethics board. METHODS: Fifteen patients who had received high-dose radiotherapy to the tracheostomy region with in vivo dose measurements were included. The radiation dose at the skin surface underneath the tracheostomy device was measured using an optically stimulated luminescent dosimeter (OSLD) and was compared with the prescribed dose from the radiation planning system. The effect of the tracheostomy flange and/or soft tissue equivalent bolus on the peristomal dose was calculated. RESULTS AND DISCUSSION: Patients with tracheostomy equipment in situ were found to have a 3.7% difference between their prescribed and actual dose. With a tissue equivalent bolus there was a 2.0% difference between predicted and actual. The mean prescribed single fraction dose (mean = 191.8 cGy, SD = 40.18) and OSLD measured dose (mean = 194.02 cGy, SD = 44.3) were found to have no significant difference. However, with the flange excluded from the planning simulation (density = air) target skin dose deviated from predicted by an average of 55.3% (range = 12.4-72.9, SD = 22.5) and volume coverage was not achieved. CONCLUSION: In summary, the tracheostomy flange acts like bolus with a twofold increase in the skin surface dose. Changes in the peristomal apparatus from simulation to treatment needs to be considered to ensure that the simulated dose and coverage is achieved.

Evaluation of a Ferromagnetic Marker Technology for Intraoperative Localization of Nonpalpable Breast Lesions.

OBJECTIVE: The purpose of this study was to evaluate the magnetic occult lesion localization instrument (MOLLI) system that involves implantation of a small, ferromagnetic marker to guide surgical excision of nonpalpable breast lesions. Characterization of the system was undertaken as part of what is, to our knowledge, the first study to assess the MOLLI system. MATERIALS AND METHODS: The MOLLI system consists of a handheld probe that can detect the position and distance of an implanted magnetic marker. The system presents the surgeon with an accurate assessment of lesion location and depth measurement for precise 3D localization. The marker is implanted under ultrasound or mammographic guidance at any time before the surgical procedure and requires no special precautions. Experimental analysis focused on characterization of the following aspects of the MOLLI system: visualization of the marker under imaging, 3D detection of the magnetic marker, spatial resolution of the probe to detect markers placed in close proximity, and the effect of signal interference on system performance. RESULTS: The MOLLI system can reliably detect mean (± SD) marker depths up to 53 ± 8.56 mm from the probe. Bracketing large lesions or localizing multiple lesions can be accomplished by placing markers as close as 10 mm apart, at depths of up to 42 mm. The biologically inert MOLLI marker is readily visible under ultrasound and mammographic guidance, and it is differentiable from radiologic clips. The effect of surgical instruments on MOLLI functioning is minimal and does not impact system accuracy or reliability. CONCLUSION: The MOLLI system offers an accurate and efficient alternative lesion localization method for nonpalpable breast lesions.

JOURNAL CLUB: Can Coronal STIR Be Used as Screening for Acute Nontraumatic Hip Pain in Children?

OBJECTIVE: The objective of this study is to evaluate whether coronal STIR MRI can be used as a screening test for nontraumatic acute hip pain in children. MATERIALS AND METHODS: From 2008 to 2012, we identified all patients younger than 18 years at our tertiary care facility who underwent pelvic MRI including coronal STIR for the following indications: acute hip pain, limping, or refusal to bear weight. Patients with a history of trauma were excluded. Each MR image was independently reviewed by four radiologists who were blinded to the clinical outcome. After first reviewing the coronal STIR images only, they then reviewed the full MRI studies in a random order different from that used for review of the coronal STIR images. The sensitivity and specificity of STIR-only images in identifying the presence of abnormality and specific diagnoses were calculated, with the full MRI study considered as the reference standard. Kappa values were calculated for STIR-only and full MRI studies. RESULTS: A total of 127 patients (67 female patients and 60 male patients; median age, 9 years; range, 5 months to 17 years) were identified. The most common abnormalities (calculated as the mean of frequency values noted by four readers) were hip effusion (52%; range, 46-58%), osteomyelitis (42%; range, 29-48%), and myositis (32%; range, 20-40%). For the detection of any abnormality, STIR-only images had a mean sensitivity of 95% and a mean specificity of 67%. For approximately one-third of STIR-only studies with true-positive results, additional abnormalities were found on full MRI studies. CONCLUSION: Coronal STIR imaging of the pelvis has high sensitivity (95%) in the detection of abnormalities associated with acute nontraumatic hip pain in children, but it often misses additional abnormalities.

Diffuse infiltrative neurofibroma: a clinical, radiological, and histological conundrum.

Diffuse infiltrative neurofibroma is a rare clinical entity that can pose a diagnostic challenge not only due to its rarity but also due to its varied clinical, radiological, and histological features. Our case illustrates how this entity may be misdiagnosed on clinical and pathological examination. Radiological imaging plays a critical and collaborative role in guiding clinicians and pathologists when faced with this challenging diagnosis.

Optimizing surface mould brachytherapy for treatment of nasal basal cell carcinoma using customized applicators.

PURPOSE: Surface mould brachytherapy (SMBT) is ideal in treating superficial skin cancer over the curved surface of the nasal ala. We describe the process of initiating and optimizing SMBT treatment at our institution including clinical workflow, generation of three dimensional (3D) printed custom applicators, and clinical outcomes. METHODS AND MATERIALS: Planning CT scans were used to acquire images for delineating target volumes. The applicator was designed with customized catheter positioning (3-5mm from target) to cover target volume while sparing dose to organs at risk (OAR) such as adjacent skin and nasal mucosa. Applicators were 3D printed, with transparent resin to aid visualization of underlying skin. Dosimetric parameters evaluated included CTV D90, CTV D0.1cc, and D2cc to OARs. Clinical outcomes assessed were local control, acute and late toxicity (Common Terminology Criteria for Adverse Events v5.0 [CTCAEv5.0]), and cosmesis (Radiation Therapy Oncology Group [RTOG]). RESULTS: Ten patients were treated with SMBT with a median followup of 17.8 months. Dose prescription was 40 Gy in 10 daily fractions. Mean CTV D90 was 38.5 Gy (range 34.7-40.6), mean CTV D0.1cc 49.2 Gy (range 45.6-53.5), which was <140% of the prescription dose in all patients. Treatment was well tolerated, with acceptable Grade 2 acute, Grade 0-1 late skin toxicity, and good-excellent cosmesis for all patients. Two patients experienced local failure, and both underwent surgical salvage. CONCLUSIONS: SMBT was successfully planned and delivered for superficial nasal BCC using 3D printed custom applicators. Excellent target coverage was achieved while minimizing dose to OAR. Toxicity and cosmesis rates were good-excellent.

Two-fraction stereotactic ablative radiotherapy with simultaneous boost to MRI-defined dominant intra-prostatic lesion - Results from the 2SMART phase 2 trial.

PURPOSE: This is the first report of the 2SMART Phase II trial evaluating the safety of two-fraction stereotactic ablative radiotherapy (SABR) with focal boost to magnetic resonance imaging (MRI) defined dominant intra-prostatic lesion (DIL) for localised prostate cancer. MATERIALS AND METHODS: Men with low or intermediate risk prostate cancer were eligible for the study. The gross tumour volume (GTV) was MRI-defined DIL, and the clinical target volume (CTV) was entire prostate gland. The planning target volume (PTV) was a 2 mm expansion anteroposterior and lateral, and 2.5 mm superoinferior. The prescribed dose was 32 Gy to GTV, and 26 Gy to CTV. Primary endpoint was minimal clinically important change (MCIC) in quality of life (QOL) within 3-months of SABR, assessed using the EPIC-26 questionnaire. Secondary endpoints were acute and late toxicities (assessed using CTCAEv4), PSA nadir, and biochemical failure (based on Phoenix criteria). RESULTS: Thirty men were enrolled in the study - 2 (7%) had low-risk and 28 (93%) had intermediate risk prostate cancer. The median follow-up was 44 months (range:39-49 months). The median PSA nadir was 0.25 ng/mL, with median time to nadir of 37 months. One patient (3%) had biochemical failure at 44 months post-treatment. Ten (33%), six (20%), and three (10%) men had acute MCIC in urinary, bowel, and sexual QOL domains respectively. No acute or late grade ≥ 3 urinary or bowel toxicities were observed. CONCLUSION: This novel protocol of two-fraction prostate SABR with MRI-defined DIL boost is a safe approach for dose-escalation, with minimal impact on acute QOL and no grade ≥ 3 toxicities.

Dosimetric correlates of toxicities and quality of life following two-fraction stereotactic ablative radiotherapy (SABR) for prostate cancer.

PURPOSE: There is no evidence-based data to guide dose constraints in two-fraction prostate stereotactic ablative radiotherapy (SABR). Using individual patient-data from two prospective trials, we aimed to correlate dosimetric parameters with toxicities and quality of life (QoL) outcomes. MATERIALS AND METHODS: We included 60 patients who had two-fraction prostate SABR in the 2STAR (NCT02031328) and 2SMART (NCT03588819) trials. The prescribed dose was 26 Gy to the prostate+/-32 Gy boost to the dominant intraprostatic lesions. Toxicities and QoL data were prospectively collected using CTCAEv4 and EPIC-26 questionnaire. The outcomes evaluated were acute and late grade ≥ 2 toxicities, and late minimal clinical important changes (MCIC) in QoL domains. Dosimetric parameters for bladder, urethra, rectum, and penile bulb were evaluated. RESULTS: The median follow-up was 56 months (range: 39-78 months). The cumulative incidence of grade ≥ 2 genitourinary (GU), gastrointestinal (GI), and sexual toxicities were 62%, 3%, and 17% respectively in the acute setting (<3 months), and 57%, 15%, and 52% respectively in late setting (>6 months). There were 36%, 28%, and 29% patients who had late MCIC in urinary, bowel and sexual QoL outcomes respectively. Bladder 0.5 cc was significant predictor for late grade ≥ 2 GU toxicities, with optimal cut-off of 25.5 Gy. Penile bulb D5cc was associated of late grade ≥ 2 sexual toxicities (no optimal cut-off was identified). No dosimetric parameters were identified to be associated with other outcomes. CONCLUSION: Using real-life patient data from prospective trials with medium-term follow-up, we identified additional dose constraints that may mitigate the risk of late treatment-related toxicities for two-fraction prostate SABR.

To Boost or Not to Boost: Pooled Analyses From 2-Fraction SABR Trials for Localized Prostate Cancer.

PURPOSE: Focal boost to dominant intraprostatic lesion (DIL) is an approach for dose escalation in prostate radiation therapy. In this study, we aimed to report the outcomes of 2-fraction SABR ± DIL boost. METHODS AND MATERIALS: We included 60 patients with low- to intermediate-risk prostate cancer enrolled in 2 phase 2 trials (30 patients in each trial). In the 2STAR trial (NCT02031328), 26 Gy (equivalent dose in 2-Gy fractions = 105.4 Gy) was delivered to the prostate. In the 2SMART trial (NCT03588819), 26 Gy was delivered to the prostate, with up to 32 Gy boost to magnetic resonance imaging-defined DIL (equivalent dose in 2-Gy fractions = 156.4 Gy). The reported outcomes included prostate-specific antigen (PSA) response (ie, <0.4 ng/mL) at 4 years (4yrPSARR), biochemical failure (BF), acute and late toxicities, and quality of life (QOL). RESULTS: In 2SMART, median DIL D99% of 32.3 Gy was delivered. Median follow-up was 72.7 months (range, 69.1-75.) in 2STAR and 43.6 months (range, 38.7-49.5) in 2SMART. The 4yrPSARR was 57% (17/30) in 2STAR and 63% (15/24) in 2SMART (P = 0.7). The 4-year cumulative BF was 0% in 2STAR and 8.3% in 2SMART (P = 0.1). The 6-year BF in 2STAR was 3.5%. For genitourinary toxicities, there were differences in grade ≥1 urinary urgency in the acute (0% vs 47%; P < .001) and late settings (10% vs 67%; P < .001) favoring 2STAR. For urinary QOL, no difference was observed in the acute setting, but lower proportion in 2STAR had minimal clinically important changes in urinary QOL score in the late setting (21% vs 50%; P = .03). There were no significant differences in gastrointestinal and sexual toxicities and QOL in both acute and late settings between the 2 trials. CONCLUSIONS: This study presents the first prospective data comparing 2-fraction prostate SABR ± DIL boost. The addition of DIL boost resulted in similar medium-term efficacy (in 4yrPSARR and BF), with impact on late urinary QOL outcomes.

GEC-ESTRO (ACROP)-ABS-CBG Consensus Brachytherapy Target Definition Guidelines for Recurrent Endometrial and Cervical Tumors in the Vagina.

PURPOSE: Representatives from the Gynecologic Groupe European de Curietherapie-European Society for Radiation Therapy and Oncology (GYN GEC-ESTRO), the American Brachytherapy Society (ABS), and the Canadian Brachytherapy Group (CBG) met to develop international consensus recommendations for target definitions for image-guided adaptive brachytherapy for vaginal recurrences of endometrial or cervical cancer. METHODS AND MATERIALS: Seventeen radiation oncologists and 2 medical physicists participated. Before an in-person meeting each participant anonymously contoured 3 recurrent endometrial/cervical cancer cases. Participants contoured the residual gross primary tumor volume (GTV-Tres), a high-risk clinical target volume (CTV-THR), and an intermediate-risk clinical target volume (CTV-TIR), on T2-weighted magnetic resonance images (MRIs). All contours were drawn using Falcon EduCase. Contours were reviewed at an in-person meeting during which a consensus document was created defining agreed-upon target definitions (Trial 1). After establishing these definitions, the group was sent one of the cases again (recurrent cervical cancer vaginal recurrence) and asked to contour the targets again (Trial 2). The Computerized Environment for Radiation Research (CERR) software (The Mathworks, Natwick, MA) was used to analyze the contours. Kappa statistics were generated to assess level of agreement between contours. A conformity index (CI), defined as the ratio between the intersection and union volume of a given pair of contours, was calculated. A simultaneous truth and performance level estimation (STAPLE) contour was created for the CTV-THR and CTV-TIR for the postmeeting case. RESULTS: Consensus definitions for GTV-Tres, CTV-THR, and CTV-TIR were established. Kappa statistics (Trial 1/Trial 2) for GTV-Tres, CTV-THR, and CTV-TIR were 0.536/0.583, 0.575/0.743 and 0.522/0.707. Kappa statistics for Trial 2 for the CTV-THR and CTV-TIR showed "substantial" agreement while the GTV-Tres remained at moderate agreement. CONCLUSIONS: This consensus provides recommendations to facilitate future collaborations for MRI-guided adaptive brachytherapy target definitions in endometrial/cervical vaginal recurrences.

COVID-19 Presenting With a Challenging Combination of Thrombocytopenia and Thrombosis.

Coronavirus disease 2019 (COVID-19) causes various hematological abnormalities, leading to several complications in the disease course. We report two COVID-19 cases presenting with a combination of thrombocytopenia and coagulopathy complications in late 2020. A 73-year-old male with a history of immune thrombocytopenic purpura (ITP) presented with acute ischemic stroke and acute thrombocytopenia in the setting of COVID-19. He was managed with steroids and intravenous immunoglobulin (IVIG) and had a subsequent acute ischemic stroke with microhemorrhages. Another 72-year-old female with a history of cryptogenic liver cirrhosis and chronic thrombocytopenia presenting with acute thrombocytopenia in the setting of COVID-19 was managed with steroids and IVIG. She had a coagulopathic complication of deep venous thrombosis (DVT) later in her disease course managed with inferior vena cava filter and low-dose enoxaparin, but she subsequently died with a bleeding complication of retroperitoneal hemorrhage. Despite the aggressive ongoing research, the treatment options for severe COVID-19 are limited to date and the mortality remains high. Both these cases are examples of challenging situations that the physicians are currently facing with COVID-19 pandemic.

A comparative study of patient-reported outcomes after contemporary radiation techniques for prostate cancer.

PURPOSE: We aim to compare health-related quality of life (HRQoL) deterioration at 12 months in low-and intermediate-risk prostate cancer (PCa) patients treated with stereotactic ablative radiotherapy (SABR), high dose-rate brachytherapy (HDR) monotherapy and HDR boost. MATERIAL AND METHODS: Patients treated as part of 7 prospective clinical trials were included. All patients had low-or intermediate-risk PCa. Three strategies were considered: SABR, HDR monotherapy and HDR boost. HRQoL was prospectively measured at baseline and 12 months in all trials, using the Expanded Prostate Index Composite (EPIC). A minimally important difference (MID) was defined as a deterioration of HRQoL scores at 12 months compared to baseline ≥0.5 standard deviation of baseline score. Univariate and multivariable logistic regression using generalized estimating equations were used to compare the proportion of patients having MID between groups. A set of sensitivity analyses was conducted. RESULTS: 648 patients were included: 288, 173 and 187 respectively in the SABR, HDR monotherapy and HDR boost group. On univariate and multivariable analyses, SABR and HDR monotherapy compared to HDR boost, were associated with less deterioration in the urinary (38%, 40% vs. 55%; OR:0.543, 95%CI:0.320-0.922, p = 0.024; OR:0.468, 95%CI:0.432-0.507, p < 0.001) and sexual domains (38%, 42% vs. 47%; OR:0.762, 95%CI:0.645-0.900, p = 0.001; OR: 0.786, 95%CI:0.650-0.949, p = 0.012). These findings wererobust to a variety ofsensitivity analyses. CONCLUSION: Recent monotherapeutic approaches for low- and intermediate-risk PCa are associated with the preservation of patients HRQoL. Ultimately, the questions of efficacy, toxicity, and HRQoL will be best answered by a randomized clinical trial.

A Prospective Study of Magnetic Resonance Imaging-guided Focal Salvage High-dose-Rate Brachytherapy for Radiorecurrent Prostate Cancer: Updated Results of 30 Patients.

PURPOSE: Limited prospective data on focal salvage high-dose-rate (HDR) prostate brachytherapy is available. We sought to explore the toxicities, health-related quality of life (HRQoL), and efficacy of focal salvage HDR brachytherapy in a prospective clinical trial. This report presents the updated results of previously published data. METHODS AND MATERIALS: Patients with locally recurrent prostate cancer after previous external beam radiation therapy and/or brachytherapy were enrolled. Patients received magnetic resonance imaging (MRI)-guided, ultrasound-based focal HDR brachytherapy delivered over 2 fractions of 13.5 Gy delivered 1 to 2 weeks apart. Androgen deprivation therapy (ADT) was not used. RESULTS: Thirty patients were treated between 2012 and 2019. At a median follow-up time of 39 months, the 3-year biochemical failure-free rate was 61.8% (95% confidence interval, 44.0%-86.6%), and the 3-year ADT/salvage therapy-free rate was 86.0% (95% confidence interval, 74.1%-99.8%). Seventeen patients experienced subsequent biochemical failure, 9 received ADT and/or further local salvage, and no patients died of prostate cancer. Of the 28 patients who had posttreatment MRI, 26 had a local treatment response. No acute grade ≥3 genitourinary/gastrointestinal toxicity was observed. One temporary late grade 3 genitourinary toxicity event occurred, but no late grade ≥3 gastrointestinal toxicity was seen. No significant decline in urinary or bowel HRQoL was observed. CONCLUSIONS: Focal salvage HDR brachytherapy has a favorable side effect profile, no significant decline in HRQoL, and the 3-year biochemical control rates are in line with those of other salvage options. Early MRI response at the treated site is common, but does not preclude subsequent biochemical failure.

Gantry-Based 5-Fraction Elective Nodal Irradiation in Unfavorable-Risk Prostate Cancer: Outcomes From 2 Prospective Studies Comparing SABR Boost With MR Dose-Painted HDR Brachytherapy Boost.

PURPOSE: Guidelines from the American Society of Clinical Oncology and Cancer Care Ontario recommend brachytherapy boost for patients with intermediate-risk or high-risk prostate cancer. SABR is an emerging technique for prostate cancer, but its use in high-risk disease is limited. Efficacy, toxic effects, and quality of life (QoL) were compared in patients treated on 2 prospective protocols that used SABR boost or magnetic resonance-guided high-dose-rate brachytherapy (HDR-BT) boost with 6 to 18 months of androgen deprivation therapy (ADT). METHODS AND MATERIALS: In SATURN study (study 1), patients received 40 Gy to the prostate and 25 Gy to the pelvis in 5 weekly fractions. In SPARE (study 2), patients received HDR-BT (15 Gy × 1) to the prostate and ≤22.5 Gy to the magnetic resonance imaging nodule, followed by 25 Gy in 5 weekly fractions to the pelvis. All patients received between 6 and 18 months of ADT. RESULTS: Thirty patients (7% unfavorable intermediate risk and 93% high risk, per National Comprehensive Cancer Network [NCCN] criteria) completed study 1, and 31 patients (3% favorable intermediate risk, 47% unfavorable intermediate risk, and 50% high risk) completed treatment as per study 2. The median follow-up times were 72 and 62 months, respectively. In study 2, 6 patients had biochemical failure, and all 6 developed metastatic disease. Actuarial 5-year biochemical failure was 0% for study 1 and 18.2% for study 2 (P = .005). There was no significant difference in the worst acute or late gastrointestinal or genitourinary toxicity. Grade 3 late genitourinary toxicity was noted in 3% of the patients in study 2 (HDR-BT boost). There was either no significant difference or minimal clinically important change in QoL. CONCLUSIONS: In the context of 5-fraction pelvic radiation therapy and ADT, there did not appear to be a significant difference in toxicity or QoL between SABR and HDR-BT boost. Although efficacy favored the SABR boost cohort, this should be viewed in the context of limitations and biases associated with comparing 2 sequential phase 2 studies.

Two-fraction stereotactic ablative radiotherapy (SABR) versus two-fraction high dose rate (HDR) brachytherapy for localized prostate cancer: Does dose heterogeneity matter?

BACKGROUND AND PURPOSE: Contemporary radiotherapy for localized prostate cancer (PCa) is deliverable via stereotactic ablative radiotherapy (SABR) and high dose rate (HDR) brachytherapy. Here we report on a parallel cohort analysis of two prospective, phase II clinical trials of two-fraction prostate SABR versus two-fraction HDR monotherapy. MATERIALS AND METHODS: Enrolled patients had histologically-confirmed PCa (clinical stage T1c-T2b; grade group 1, 2, or 3; and PSA < 20 ng/mL). SABR and HDR doses were 26 Gy and 27 Gy in 2 weekly fractions, respectively. Patient-level data from each cohort was analysed to assess prostate specific antigen (PSA) response kinetics, biochemical failure, toxicity, and quality of life (QOL). RESULTS: Thirty patients receiving SABR and 83 receiving HDR were included. Fifty percent and 30% of patients had unfavourable-intermediate risk disease, respectively. SABR patients had higher mean baseline PSA (8.7 versus 6.8 ng/mL, p = 0.016). Median follow-up was 72.7 and 65.3 months, respectively. Mean dose delivered (Dmean) was 26.6-26.8 Gy for SABR versus 35.5-45.5 Gy for HDR. Both cohorts achieved a median nadir PSA of 0.16 ng/mL at a median of 57 months post-treatment. Cumulative biochemical failure probability (±SE) at 72 months was 3.5% (±3.5%) for SABR versus 12.8% (±4.8%) for HDR (p = 0.19). Low rates of CTCAE grade ≥2 toxicity were observed in both cohorts. No differences in EPIC scores over time were observed between cohorts. CONCLUSIONS: Two-fraction SABR yields similar rates of biochemical failure, acute and late toxicities, and QOL as two-faction HDR brachytherapy. These data support the design of a randomized controlled trial comparing these treatments.

A comparison of postimplant dosimetry for (103)Pd versus (131)Cs seeds on a retrospective series of PBSI patients.

PURPOSE: Permanent breast seed implantation (PBSI) is an accelerated partial breast irradiation technique performed using stranded (103)Pd radioactive seeds (average energy of 21 keV, 16.97 day half-life). Since 2004, (131)Cs brachytherapy sources have become clinically available. The (131)Cs radionuclide has a higher energy (average energy of 30 keV) and a shorter half-life (9.7 days) than (103)Pd. The purpose of this study was to determine whether or not there are dosimetric benefits to using (131)Cs brachytherapy seeds for PBSI. METHODS: The prescribed dose for PBSI using (103)Pd is 90 Gy, which was adjusted for (131)Cs implants to account for the shorter half-life. A retrospective cohort of 30 patients, who have already undergone a (103)Pd implant, was used for this study. The treatments were planned using the Variseed treatment planning system. The air kerma strength of the (131)Cs seeds was adjusted in all preimplantation treatment plans so that the V(100) (the volume within the target that receives 100% or more of the prescribed dose) were equivalent at time of implantation. Two month follow-up CT scans were available for all 30 patients and each patient was reevaluated using (131)Cs seeds. The postimplant dosimetric parameters were compared using a two tailed t-test. RESULTS: The prescribed dose for (131)Cs was calculated to be 77 Gy; this dose would have the same biological effect as a PBSI implant with (103)Pd of 90 Gy. The activities of the (131)Cs sources were adjusted to an average of 2.2 ± 0.8 U for (131)Cs compared to 2.5 ± 1.1 U for (103)Pd in order to get an equivalent V(100) as the (103)Pd preimplants. While the use of (131)Cs significantly reduces the preimplant V(200) (the volume within the target that receives 200% or more of the prescribed dose) compared to (103)Pd by 13.5 ± 9.0%, the reduction observed on the 2 month postimplant plan was 12.4 ± 5.1% which accounted for seed motion, implantation inaccuracies and tissue changes. This translates into an absolute reduction of 4.1 cm(3) of tissue receiving 200% of the dose. CONCLUSIONS: This analysis of 30 early stage breast cancer patients who underwent the PBSI procedure shows that there is a theoretical dosimetric advantage to using (131)Cs. However, in a realistic implant that will have seed misplacements and tissue changes, the use of (131)Cs may not result in any clinically significant benefit.