Acute toxicity outcomes from salvage high-dose-rate brachytherapy for locally recurrent prostate cancer after prior radiotherapy.

Purpose: Isolated intra-prostatic recurrence of prostate adenocarcinoma after definitive radiotherapy presents a challenging clinical scenario. Salvage options require specialized expertise and pose risks of harm. This study aimed to present the acute toxicity results from using salvage high-dose-rate brachytherapy (sHDR-BT) as treatment in locally recurrent prostate cancer cases. Material and methods: Seventeen consecutive patients treated with sHDR-BT between 2019 and 2022 were evaluated retrospectively. Eligible patients had to have received curative intent prostate radiotherapy previously, and showed evidence of new biochemical failure. Evaluation with American Urological Association (AUA) and Common Terminology Criteria for Adverse Events (CTCAE) symptom assessments were performed for each case. Results: The median (inter-quartile range) age prior to salvage treatment was 68 (66-74) years. The median post-sHDR-BT follow-up time was 20 (13-24) months. At baseline prior to sHDR-BT, 8 (47%) patients had significant lower urinary tract symptoms. The median AUA score prior to sHDR-BT was 7 (3-18). Three (18%) patients reported irregular bowel function and 2 (12%) reported hematochezia prior to sHDR-BT. One-month post-treatment, the median AUA score was 13 (8-21, p = 0.21). Using CTCAE scoring, there were no cases of grade 2+ bowel or rectal toxicity, and no cases of grade 3+ urinary toxicity. Reported grade 2 urinary toxicities included 10 (59%) cases of bladder spasms, 2 (12%) cases of incontinence, 1 (6%) urinary obstruction, and 4 (24%) reports of urinary urgency. All these adverse events were temporary. Conclusions: This study adds to the existing literature by demonstrating that the acute toxicity profile of sHDR-BT is acceptable even without intra-operative magnetic resonance (MR) guidance or image registration. Further study is ongoing to determine long-term efficacy and toxicity of treatment.

The impact of advancing the standard of care in radiotherapy on operational treatment resources.

PURPOSE: To demonstrate the impact of implementing hypofractionated prescription regimens and advanced treatment techniques on institutional operational hours and radiotherapy personnel resources in a multi-institutional setting. The study may be used to describe the impact of advancing the standard of care with modern radiotherapy techniques on patient and staff resources. METHODS: This study uses radiation therapy data extracted from the radiotherapy information system from two tertiary care, university-affiliated cancer centers from 2012 to 2021. Across all patients in the analysis, the average fraction number for curative and palliative patients was reported each year in the decade. Also, the institutional operational treatment hours are reported for both centers. A sub-analysis for curative intent breast and lung radiotherapy patients was performed to contextualize the impact of changes to imaging, motion management, and treatment technique. RESULTS: From 2012 to 2021, Center 1 had 42 214 patient plans and Center 2 had 43 252 patient plans included in the analysis. Averaged over both centers across the decade, the average fraction number per patient decreased from 6.9 to 5.2 (25%) and 21.8 to 17.2 (21%) for palliative and curative patients, respectively. The operational treatment hours for both institutions increased from 8 h 15 min to 9 h 45 min (18%), despite a patient population increase of 45%. CONCLUSION: The clinical implementation of hypofractionated treatment regimens has successfully reduced the radiotherapy workload and operational treatment hours required to treat patients. This analysis describes the impact of changes to the standard of care on institutional resources.

Prospective validation of a machine learning model for applicator and hybrid interstitial needle selection in high-dose-rate (HDR) cervical brachytherapy.

PURPOSE: To Demonstrate the clinical validation of a machine learning (ML) model for applicator and interstitial needle prediction in gynecologic brachytherapy through a prospective clinical study in a single institution. METHODS: The study included cervical cancer patients receiving high-dose-rate brachytherapy using intracavitary (IC) or hybrid interstitial (IC/IS) applicators. For each patient, the primary radiation oncologist contoured the high-risk clinical target volume on a pre-brachytherapy MRI, indicated the approximate applicator location, and made a clinical determination of the first fraction applicator. A pre-trained ML model predicted the applicator and IC/IS needle arrangement using tumor geometry. Following the first fraction, ML and radiation oncologist predictions were compared and a replanning study determined the applicator providing optimal organ-at-risk (OAR) dosimetry. The ML-predicted applicator and needle arrangement and the clinical determination were compared to this dosimetric ground truth. RESULTS: Ten patients were accrued from December 2020 to October 2022. Compared to the dosimetrically optimal applicator, both the radiation oncologist and ML had an accuracy of 70%. ML demonstrated better identification of patients requiring IC/IS applicators and provided balanced IC and IC/IS predictions. The needle selection model achieved an average accuracy of 82.5%. ML-predicted needle arrangements matched or improved plan quality when compared to clinically selected arrangements. Overall, ML predictions led to an average total improvement of 2.0 Gy to OAR doses over three treatment fractions when compared to clinical predictions. CONCLUSION: In the context of a single institution study, the presented ML model demonstrates valuable decision-support for the applicator and needle selection process with the potential to provide improved dosimetry. Future work will include a multi-center study to assess generalizability.

Prevalence and Prognostic Significance of PIK3CA Mutation and CNV Status and Phosphorylated AKT Expression in Patients With Cervical Cancer Treated With Primary Surgery.

Currently, there are limited and conflicting reports on the prognostic utility of PIK3CA and associated pathway markers for cervical cancers treated with primary surgical management. Moreover, current studies are lacking complete characterization of adjuvant treatment with RT and/or chemotherapy. We aimed to document the prevalence, clinicopathologic, adjuvant treatment details, and prognostic value of PI3K/AKT pathway mutations and copy number variation and phosphorylated AKT status in patients with cervical cancers treated with primary surgery. A clinicopathologic review was performed on a retrospective cohort of 185 patients with cervical cancer, treated with primary surgery at a single tertiary institution. Next-generation sequencing and digital PCR was used to determine PI3K/AKT pathway mutational status and PIK3CA copy number variation, respectively, and fluorescent immunohistochemistry measured phosphorylated AKT expression. In all, 179 of 185 (96.8%) of tumors were successfully sequenced; 48 (26.8%) were positive for PI3K/AKT pathway mutations-the majority (n=37, 77.1%) PIK3CA mutations. PIK3CA mutation was associated with pathologically positive lymph nodes [12 (32%) vs. 22 (16%); P =0.022] and indication for postoperative chemoradiotherapy [17 (45.9%) vs. 32 (22.5%); P =0.004]. On multivariable analysis, PIK3CA status was not associated with overall survival ( P =0.103) or progression-free survival ( P =0.240) at 5 yrs, nor was PIK3CA copy number variation status. phosphorylated AKT ≤ median significantly predicted for progression-free survival [multivariable hazard ratio 0.39 (0.17-0.89; P =0.025)] but not overall survival ( P =0.087). The correlation of PIK3CA with pathologic positive lymph node status yet lack of association with survival outcomes may be due to the use of adjuvant postoperative therapy. PIK3CA assessment before radical hysterectomy may help identify patients with a higher risk of node-positive disease.

Is Ultrahypofractionated Whole Pelvis Radiation Therapy (WPRT) as Well Tolerated as Conventionally Fractionated WPRT in Patients With Prostate Cancer? Early Results From the HOPE Trial.

OBJECTIVE: The aim of this work was to evaluate the acute toxicity and quality-of-life (QOL) impact of ultrahypofractionated whole pelvis radiation therapy (WPRT) compared with conventional WPRT fractionation after high-dose-rate prostate brachytherapy (HDR-BT). METHODS AND MATERIALS: The HOPE trial is a phase 2, multi-institutional randomized controlled trial of men with prostate-confined disease and National Comprehensive Cancer Network unfavorable intermediate-, high-, or very-high-risk prostate cancer. Patients were randomly assigned to receive conventionally fractionated WPRT (standard arm) or ultrahypofractionated WPRT (experimental arm) in a 1:1 ratio. All patients underwent radiation therapy with 15 Gy HDR-BT boost in a single fraction followed by WPRT delivered with conventional fractionation (45 Gy in 25 daily fractions or 46 Gy in 23 fractions) or ultrahypofractionation (25 Gy in 5 fractions delivered on alternate days). Acute toxicities measured during radiation therapy and at 6 weeks posttreatment were assessed using the clinician-reported Common Terminology Criteria for Adverse Events version 5.0, and QOL was measured using the Expanded Prostate Cancer Index Composite (EPIC-50) and International Prostate Symptom Score (IPSS). RESULTS: A total of 80 patients were enrolled and treated across 3 Canadian institutions, of whom 39 and 41 patients received external radiation therapy with conventionally fractionated and ultrahypofractionated WPRT, respectively. All patients received androgen deprivation therapy except for 2 patients treated in the ultrahypofractionated arm. The baseline clinical characteristics of the 2 arms were similar, with 51 (63.8%) patients having high or very-high-risk prostate cancer disease. Treatment was well tolerated with no significant differences in the rate of acute adverse events between arms. No grade 4 adverse events or treatment-related deaths were reported. Ultrahypofractionated WPRT had a less detrimental impact on the EPIC-50 bowel total, function, and bother domain scores compared with conventional WPRT in the acute setting. By contrast, more patients treated with ultrahypofractionated WPRT reached the minimum clinical important difference on the EPIC-50 urinary domains. No significant QOL differences between arms were noted in the sexual and hormonal domains. CONCLUSIONS: Ultrahypofractionated WPRT after HDR-BT is a well-tolerated treatment strategy in the acute setting that has less detrimental impact on bowel QOL domains compared with conventional WPRT.

Assessment of dose to vaginal mucosa for gynecologic template interstitial high-dose-rate brachytherapy using Monte Carlo simulation.

Purpose: This study investigated reliable vaginal mucosa dose-volume histogram (DVH) metrics in gynecologic template interstitial high-dose-rate brachytherapy (HDR-BT) for the purpose of standardized dose reporting. Material and methods: Gynecologic template (Syed/Neblett) interstitial HDR-BT patients treated from September 2016 to November 2022 at the study institute were included in the cohort. Each patient implant included a vaginal mucosa contour defined by a 5 mm expansion from vaginal cylinder, then another volume with clinical target volume subtracted. DVH metrics were investigated between D0.1cc to D4cc. Clinical plans were re-calculated using Monte Carlo (MC) simulations both in heterogeneous material and in water. Results: The patient cohort included 61 patients with clinical plans using conventional homogeneous dose calculation (TG43). Heterogeneous vs. water MC dose differences were between -1.1% and -1.4% for all metrics investigated. DVH metrics D1cc and smaller resulted in > 5% discrepancies between TG43 and MC dose (to water) calculation due to the proximity of source positions in/nearby the vaginal mucosa. Reliability improved when DVH metric volume was larger (D2cc and D4cc). Both D2cc and D4cc presented very high linear correlation between TG43 and MC reported doses for the vagina, and average ± standard deviation dose difference was 4.6 ±2.9% and -3.0 ±1.9%, respectively. Dose differences decreased when the clinical target volume was removed: -1.5 ±3.5% and -0.8 ±2.1% for D2cc and D4cc, respectively. Conclusions: For perineal template gynecologic HDR-BT procedures, the 2 cc volume is the smallest representative volume that reliably reports vaginal dose and at minimum should be reported to establish dose and outcome evaluation.

Clinical implementation of 3D transvaginal ultrasound for intraoperative guidance of needle implant in template interstitial gynecologic high-dose-rate brachytherapy.

PURPOSE: To demonstrate novel clinical implementation of a 3D transvaginal ultrasound (3DTVUS) system for intraoperative needle insertion guidance in perineal template interstitial gynecologic high-dose-rate brachytherapy and assess its impact on implant quality. METHODS AND MATERIALS: Interstitial implants began with preimplant 3DTVUS to visualize the tumor and anatomy, with intermittent 3DTVUS to assess the implant and guide needle adjustment. Analysis includes visualization of the implant relative to anatomy, identification of cases where 3DTVUS is beneficial, dosimetry, and a survey distributed to 3DTVUS clinicians. RESULTS: Seven patients treated between November 2021 and October 2022 were included in this study. Twenty needles were inserted under 3DTVUS guidance. The tumor and vaginal wall were well-differentiated in four and all seven patients, respectively. Patients with tumours below the superior aspect of the vagina are suited for 3DTVUS. Four radiation oncologists responded to the survey. There was general agreement that 3DTVUS improves implant and anatomy visualization and is preferred over standard 2D ultrasound guidance techniques. CONCLUSIONS: Based on qualitative feedback from primary users and a small preliminary patient cohort, 3DTVUS imaging improves tumor and vaginal wall visualization during gynecologic perineal template interstitial needle implant and is a powerful tool for implant assessment in an intraoperative setting.

Estimated absolute percentage of biopsied tissue positive for Gleason pattern 4 (eAPP4) in low dose rate prostate brachytherapy: Evaluation of prognostic utility in a large cohort.

PURPOSE: To determine whether a system to estimate Absolute Percentage of Biopsied Tissue Positive for Gleason Pattern 4 (eAPP4) is useful as a prognostication tool for patients with intermediate risk prostate cancer (IR-PCa) undergoing low dose rate prostate brachytherapy. METHODS: 497 patients with IR-PCa and known grade group 2 or 3 disease treated with low dose rate seed brachytherapy (LDR-BT) at a quaternary cancer centre were retrospectively reviewed. Prostate biopsies for each patient included Gleason grading with synoptic reporting that did not include percentage of pattern 4 disease found within the sample. Each core was assigned a grade grouping, however, and that was used with optimized estimates of percentage of pattern four disease to estimate eAPP4. Outcomes including cumulative incidence of recurrence (CIR), treatment of recurrent disease (RRX), and metastasis-free survival (MFS) were then reviewed and the prognostic value of eAPP4 evaluated. RESULTS: 428 (86%) patients had Gleason grade group 2 and 69 (14%) patients had Gleason grade group 3 disease. 230 (46%) patients had National Comprehensive Cancer Network (NCCN) favourable intermediate at baseline, while 267 (54%) of patients had NCCN unfavourable intermediate at baseline. Median follow-up was 7.3 (5.5-9.6) years. eAPP4 was predictive of CIR (p = 0.003), RRX (p = 0.003), or MFS (p = 0.001) events, while Gleason grade grouping alone was not. eAPP4 was strongest as a predictor for MFS when estimates of 30% (grade group 2) and 80% (grade group 3) were used [HR 1.07 (1.03-1.12); p = 0.001]. CONCLUSIONS: eAPP4 was strongly predictive of recurrence and metastasis-free survival in a large cohort of patients receiving LDR-BT treatment for IR-PCa. Treatment of future patients with IR-PCa could include the use of eAPP4 prognostication.

Local Prostate Radiation Therapy and Symptomatic Local Events in De Novo Metastatic Prostate Cancer.

PURPOSE: Local prostate radiation therapy (LPRT) for low-burden metastatic prostate cancer (mPCa) improves overall survival and is the standard of care. The role of LPRT in reducing symptomatic local events (SLE) remains unclear. We aimed to identify SLE risk factors and to evaluate the association between LPRT and SLE in mPCa. METHODS AND MATERIALS: We conducted a retrospective, population-based cohort study of patients initially diagnosed with mPCa between 2005 and 2016 in a cancer registry. Patient, tumor, and treatment characteristics were obtained from chart review and the cancer registry. The coprimary endpoints were genitourinary (GU) and gastrointestinal (GI) SLE, identified by physician billing claims between 2004 and 2017 for diagnostic or therapeutic procedures potentially related to GU and GI SLE. The effect of LPRT on SLE was evaluated using both recurrent event (Andersen-Gill model) and time-to-first-event sequential landmark analyses. Risk factors for SLE were assessed by multivariable Cox regression. LPRT was defined as ≥40 Gy within 1 year of diagnosis. Metastatic burden was defined per the STAMPEDE trial. RESULTS: Of 1363 patients, 46 (3.4%) received LPRT. Median follow-up was 27.3 and 28.9 months in the control and LPRT groups, respectively. LPRT was associated with less recurrent GU SLE (hazard ratio [HR], 0.34; 95% confidence interval [CI], 0.17-0.67; P = .002), upper tract obstruction (HR, 0.20; 95% CI, 0.05-0.84; P = .03), and cystoscopy (HR, 0.38; 95% CI, 0.15-0.96; P = .04). Metastatic burden was not associated with SLE. CONCLUSIONS: LPRT in mPCa was associated with less recurrent GU SLE, specifically for upper tract obstruction and cystoscopy.

Opioid consumption and pain in patients with gynecological cancer who underwent spinal anesthesia vs. general anesthesia for interstitial brachytherapy.

AIMS: Interstitial brachytherapy (ISBT) is an effective option for delivering conformal high dose radiation to the target volume with better organ-at risk sparing but is thought to be more invasive and painful than other methods. This study investigated pain levels and opioid consumption in patients who received spinal anesthesia (SA) or general anesthesia (GA) for their ISBT. MATERIALS AND METHODS: Patients that underwent ISBT from April 2014 to September 2018 were analyzed from a prospective institutional database. The most prevalent malignancies were cervical (45%), recurrent endometrial (27%) and vaginal (20%) cancers. Baseline patient characteristics, radiation treatment details, anesthesia records, and inpatient charts were obtained. Opioid consumption was quantified as oral morphine equivalent per day (OMEq/day) from implantation until removal. Pain score levels were collected by using an 11-point scoring system. RESULTS: Ninety nine patients received GA and 40 patients received SA as their anesthesia for ISBT. During their first admission, 76 patients (55%) required intravenous opioids. Patients receiving SA had significantly lower mean pain scores on the morning of their procedure 6 (Interquartile range [IQR] 2-8) vs. 0 (IQR: 0-1); p < 0.001]. Pain did not significantly differ between cohorts at any other time. During the first admission, SA patients had a lower median opioid usage of 23 (IQR: 9-47) mg/day compared to GA patients at 38 (IQR: 21-71) mg/day (p = 0.011). No difference in opioid consumption was seen during subsequent admissions. CONCLUSIONS: In patients undergoing ISBT, SA provides better immediate pain control post insertion compared to GA. Patients who received SA used lower amounts of opioids during their first ISBT insertion.

Indications for additional volume studies for gland volume estimation in prostate cancer brachytherapy.

An estimated gland volume of > 60 cc is a relative contraindication to brachytherapy for prostate cancer. As volume estimation using biopsy ultrasound (Bx-US) alone may be inaccurate, many centers perform additional volume assessments prior to the brachytherapy procedure. At the study institution, computed tomography (CT) based volume assessments were routinely performed on all patients to determine brachytherapy eligibility. This study aimed to determine whether this CT imaging could be omitted for certain Bx-US based gland volume estimates. To investigate this, 1576 consecutive patients that received ultrasound based intraoperatively planned brachytherapy at a single comprehensive cancer center between 2003 and 2021 were reviewed. Gland volume as estimated by Bx-US, CT and magnetic resonance (MR) imaging were compared to intraoperatively contoured gland volume (ICGV) or the larger contoured gland volume on CT for any patients receiving neo-adjuvant androgen deprivation therapy (ADT) for gland downsizing (IM-US-corr). There was a significant difference between IM-US-corr and estimated gland volume for Bx-US (P < 0.001) and MR (P < 0.001), but not CT (P = 0.160). Bx-US and MR tended to underrepresent the IM-US-corr, with a > 20% difference from actual volume in 31% and 59% of cases, respectively. When Bx-US volume was estimated to be < 40 cc, < 50 cc and < 60 cc, an IM-US-corr > 60 cc was encountered in 2%, 5% and 7% of cases, respectively. In contrast, IM-US-corr > 60 cc was encountered in 0.2%, 1% and 2% of cases for CT estimates of < 40 cc, < 50 cc and < 60 cc. In patients with an estimated gland volume of < 50 cc by Bx-US, dedicated pre-operative volume studies are unlikely to alter management. However, patients above this cut-off stand to benefit from the use of additional volume assessment to better delineate gland volume and determine eligibility for brachytherapy.

Success of targeted transperineal biopsy in patients on surveillance for grade group 1 prostate cancer.

INTRODUCTION: We aimed to determine the minimum cross-sectional ellipsoid area on magnetic resonance (MR) of intraprostatic nodules that best predicts for subsequent targeted biopsies revealing ≥ grade group (GG) 2 disease. METHODS: Forty-six patients previously diagnosed with GG 1 prostate adenocarcinoma who received cognitively fused, MR-guided, transperineal targeted biopsies in addition to six random biopsies were included in this analysis. A Youden cutpoint analysis was used to determine the ellipsoid area in the axial plane best predicting for ≥GG 2 disease within the targeted biopsy cores and logistic regression used to assess the result. RESULTS: Median time from MR imaging to targeted biopsy was 2.4 (1.4-5.5) months. Forty of 46 (87%) patients had one nodule and 6/46 (13%) had two separate nodules on MR that received targeted biopsy. Of the 52 nodules, five (10%), 33 (63%), and 14 (27%) were Prostate Imaging-Reporting and Data System (PI-RADS) 3, 4, and 5, respectively. Thirteen (25%), six (12%), and 33 (64%) were in the anterior, medial, and posterior regions of the prostate, respectively. Median area was 0.72 (0.49-1.29) cm2 (average diameter 9.5 mm). Fifteen of 46 (33%) patients had ≥1 random biopsy and 20/52 (38%) nodules had ≥1 targeted biopsy revealing ≥GG 2 disease. The optimal area cutpoint was ≥0.7 cm2, with an area under the curve of 0.671 (0.510-0.832). On logistic regression, area ≥0.7 cm2 was solely predictive of targeted biopsy revealing ≥GG 2 disease (odds ratio 6.5, 1.3-32.4, p=0.022). CONCLUSIONS: Nodule area ≥0.7 cm2 may predict for transperineal-based targeted biopsies being positive for ≥GG 2 disease when 1-2 cores are taken.

Increasing Demand on Human Capital and Resource Utilization in Radiation Therapy: The Past Decade.

PURPOSE: To quantify the change resource utilization in radiation therapy in the context of advancing technologies and techniques over the last decade. METHODS AND MATERIALS: Prospectively, the time to complete radiation therapy workflow tasks was captured between January 1, 2020, and December 31, 2020. The institutional task workflows are specific to each technique and broadly organized into 4 categories: 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric modulated arc therapy complex. These discipline-specific task times were used to quantify a resource utilization factor, which is the median time taken to complete all tasks for each category divided by the median time for 3-dimensional conformal radiation therapy treatments. Retrospectively, all plans treated between January 1, 2012, and December 31, 2019, were quantified and categorized. The resource factor was applied to determine resource utilization. For context, institutional staffing levels were captured across the same decade for medical dosimetrists, medical physicists, and radiation oncologists. RESULTS: This analysis includes 30,229 patient plans in the retrospective data set and 4747 patient plans in the prospective data set. This analysis demonstrates that over this period, patient numbers increased by approximately 45%, whereas time-based human resources increased by almost 150%. The resource allocation factors for 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric arc therapy complex were 1.0, 2.4, 2.9, and 4.3, respectively. Across the 3 disciplines, staffing levels increased from 15 to 17 (13%) for medical dosimetrists, from 10 to 13 (30%) for medical physicists, and from 16 to 23 (44%) for radiation oncologists. CONCLUSIONS: This work demonstrates the increase in resource utilization due to the introduction of advanced technologies and changes in radiation therapy techniques over the past decade. Human resource utilization is the predominant factor and should be considered with increasing patient volume for operational planning.

Changing Landscape of Radiation Therapy for Advanced Cervical Cancer With a Focus on Interstitial Brachytherapy: A Canadian Practice Patterns Survey.

PURPOSE: To document the evolution of radical radiation therapy and interstitial brachytherapy (ISBT) utilization practice patterns across Canada, including use of imaging, technical details, and usage of anesthesia/analgesia, and to compare advanced (AC) versus nonadvanced (nAC) brachytherapy (BT) center practices. METHODS AND MATERIALS: All Canadian centers with BT services were identified. One gynecology radiation oncologist per center was sent a 64-item questionnaire regarding the center's practice for patients with cervical cancer. Centers were categorized based on availability of advanced BT expertise (AC) versus those referring patients to other centers for advanced BT techniques (nAC). Aggregate responses are reported and compared with practice patterns identified in our previous survey. Descriptive statistics were used to summarize data, and the Fisher exact test, Fisher-Freeman-Halton, or Mann-Whitney-Wilcox test was used for comparisons. RESULTS: Thirty-seven of 38 respondents completed the survey (response rate: 97.4%). Compared with 2015, there has been an increase in utilization of magnetic resonance imaging as the sole imaging modality for BT planning: 3 of 26 (11%) versus 12 of 37 (32%; P = .03). The number of centers with the ability to perform ISBT increased in 2020 compared with 2015 (26/37 [70%] vs 13/26 [50%], P = .710); this trend is likely due to an increase in use of hybrid (Vienna, Utrecht, Venezia) applicators (36% [2015] vs 84% [2020]; P = .175). Fifteen (40%) centers had the ability to perform perineal-ISBT (P-ISBT). Sixteen and 21 centers were identified as AC and nAC, respectively. All 16 AC centers had the ability to perform ISBT, compared with only 10 nAC centers (P < .001). A higher proportion of AC centers had fellowship-trained radiation oncologists performing brachytherapy, compared with nAC centers (94% vs 14%, P < .001). In terms of anesthesia, conscious sedation was the only available choice at low-patient-volume centers (8/37, 21%) performing intracavitary BT only. Those performing ISBT had choice of general, spinal, and epidural anesthesia. CONCLUSIONS: In Canada, high-quality, modern management radiation therapy practices are consistently offered to patients with cervical cancer. There is a trend toward increased utilization of ISBT. Accumulation of evidence toward the use of ISBT, increased utilization of high-quality imaging modalities such as magnetic resonance imaging, and availability of hybrid applicators are potential contributors for this upward trend.

Clinical Outcomes from Dose-Reduced Radiotherapy to the Prostate in Elderly Patients with Localized Prostate Cancer.

Radical treatment of localized prostate cancer in elderly patients may lead to unacceptable treatment-associated toxicities that adversely impact quality of life without improving survival outcomes. This study reports on a cohort of 54 elderly (>70 years) patients that received 4000-5000 cGy of palliative external beam radiotherapy (EBRT) as an alternative to androgen deprivation therapy (ADT). The primary outcome of interest was the period of ADT-free survival, and secondary outcomes included overall survival (OS) and metastases-free survival (MFS). Kaplan-Meier regression was used to estimate survival outcomes. Thirty-six (67%) patients achieved a break in ADT post-radiotherapy, with a median time to ADT reinitiation of 20 months. Common Terminology Criteria for Adverse Events (CTCAE) were limited to low-grade gastrointestinal (GI) or genitourinary (GU) toxicities, with no skin toxicities observed. Grade 1 GI toxicity was observed in 9 (17%) patients, and grades 1 and 2 GU toxicities were observed in 13 (24%) and 3 (6%) patients, respectively, with no higher-grade toxicities reported. Five-year MFS and OS were 56% and 78%, respectively. In summary, the treatment regimen was well-tolerated and achieved durable ADT-free survival in most patients. Dose-reduced EBRT appears to be a viable alternative to ADT in elderly patients with localized prostate cancer.

MRI-TRUS registration methodology for TRUS-guided HDR prostate brachytherapy.

PURPOSE: High-dose-rate (HDR) prostate brachytherapy is an established technique for whole-gland treatment. For transrectal ultrasound (TRUS)-guided HDR prostate brachytherapy, image fusion with a magnetic resonance image (MRI) can be performed to make use of its soft-tissue contrast. The MIM treatment planning system has recently introduced image registration specifically for HDR prostate brachytherapy and has incorporated a Predictive Fusion workflow, which allows clinicians to attempt to compensate for differences in patient positioning between imaging modalities. In this study, we investigate the accuracy of the MIM algorithms for MRI-TRUS fusion, including the Predictive Fusion workflow. MATERIALS AND METHODS: A radiation oncologist contoured the prostate gland on both TRUS and MRI. Four registration methodologies to fuse the MRI and the TRUS images were considered: rigid registration (RR), contour-based (CB) deformable registration, Predictive Fusion followed by RR (pfRR), and Predictive Fusion followed by CB deformable registration (pfCB). Registrations were compared using the mean distance to agreement and the Dice similarity coefficient for the prostate as contoured on TRUS and the registered MRI prostate contour. RESULTS: Twenty patients treated with HDR prostate brachytherapy at our center were included in this retrospective evaluation. For the cohort, mean distance to agreement was 2.1 ± 0.8 mm, 0.60 ± 0.08 mm, 2.0 ± 0.5 mm, and 0.59 ± 0.06 mm for RR, CB, pfRR, and pfCB, respectively. Dice similarity coefficients were 0.80 ± 0.05, 0.93 ± 0.02, 0.81 ± 0.03, and 0.93 ± 0.01 for RR, CB, pfRR, and pfCB, respectively. The inclusion of the Predictive Fusion workflow did not significantly improve the quality of the registration. CONCLUSIONS: The CB deformable registration algorithm in the MIM treatment planning system yielded the best geometric registration indices. MIM offers a commercial platform allowing for easier access and integration into clinical departments with the potential to play an integral role in future focal therapy applications for prostate cancer.

Excessive waitlists and delays to treatment with low-dose-rate brachytherapy predict an increased risk of recurrence and metastases in intermediate-risk prostatic carcinoma.

PURPOSE: It has previously been shown that increased wait times for prostatectomy are associated with poorer outcomes in intermediate-risk prostatic carcinoma (PCa). However, the impact of wait times on PCa outcomes following low-dose-rate brachytherapy (LDR-BT) are unknown. METHODS AND MATERIALS: We retrospectively reviewed 466 intermediate-risk PCa patients that underwent LDR-BT at a single comprehensive cancer center between 2003 and 2016. Wait times were defined as the time from biopsy to LDR-BT. The association of wait times with outcomes was evaluated using Cox and Fine-Gray regression in both univariate and multivariate models. RESULTS: Median (interquartile range) follow-up and wait time for all patients were 8.1 (6.3-10.4) years and 5.1 (3.9-6.9) months, respectively. Among NCCN unfavourable intermediate-risk (UIR) patients (n = 170; 36%), increased wait times predicted both a greater cumulative incidence of recurrence [MHR = 1.01/month of wait time (95% CI: 1.00-1.03); P = 0.044] and metastases [MHR = 1.04/month of wait time (95% CI: 1.02-1.06); P < 0.001] in multivariate modeling. In NCCN favourable intermediate-risk (FIR) patients, there was no significant association between wait time and recurrence or metastases risk. Among all intermediate-risk patients, wait time was associated with an increase in the incidence of metastases [MHR = 1.03/month of wait time (95% CI: 1.02-1.05); P < 0.001], but not recurrence in multivariate models. There was no association between wait time and overall survival in the UIR, FIR, or all intermediate-risk cohorts. CONCLUSIONS: Resource constraints within this center's public healthcare system have contributed to waitlists exceeding 5-months in length. This study finds that patients with UIR PCa experience a 1% increase in the risk of recurrence and 4% increase in the risk of metastases with each additional month of delay in definitive disease management. Preventing such extended management delays in LDR-BT may improve disease-related outcomes in patients with PCa.

Complications and side effects of high-dose-rate prostate brachytherapy.

PURPOSE: To describe technical challenges and complications encountered during and after high-dose-rate prostate brachytherapy (HDR-BT) and review management of these complications. METHODS AND MATERIALS: The authors performed a systematic review of the literature on toxicities encountered after prostate HDR-BT +/- external beam radiotherapy. A total of 397 studies were identified, of which 64 were included. A focused review of literature regarding the management of acute and late toxicities also performed. RESULTS: Most acute toxicities include grade 0-2 genitourinary and gastrointestinal toxicity. Overall, Grade 3+ Common Terminology Criteria for Adverse Events toxicity after HDR-BT was low [genitourinary: 0-1%; gastrointestinal 0-3%]. Rates of fistula formation were <1%, and radiation cystitis/proctitis were <14% and more commonly reported in cohorts treated with HDR-BT boost and external beam radiotherapy. CONCLUSIONS: HDR-BT both as monotherapy or combined with external beam radiotherapy for prostate cancer is well tolerated. Serious complications are rare.

Substantial lymphovascular space invasion predicts worse outcomes in early-stage endometrioid endometrial cancer.

INTRODUCTION: Substantial as opposed to focal or no lymphovascular space invasion (LVSI) is proposed as an independent adverse prognostic factor in patients with early-stage endometrioid endometrial cancer (EEC). We reviewed outcomes of patients treated with adjuvant vaginal brachytherapy (VB) alone in a single institution, stratified by LVSI extent. METHODS AND MATERIALS: Retrospective review identified Stage I-II EEC patients receiving VB alone from 2010 to 2017. Extent of LVSI was reported as none, focal, or substantial. Kaplan-Meier estimates and Log-Rank test were used to determine significance between variables. Cox proportional hazards model was used for multivariate analyses. RESULTS: In total, 325 patients were identified with a median follow-up of 35 (23-48) months. LVSI was found in 112 patients with extent reported in 78, 45 (58%) had focal, and 33 (42%) substantial LVSI. Estimated disease-free survival for those with substantial LVSI was 73 (57-94)%, focal LVSI 89 (79-100)%, and no LVSI 94 (90-98)% at 48 months (p = 0.012). On multivariate analyses substantial LVSI was the only risk factor predictive of pelvic [HR substantial vs no: 7.2 (1.0-51.6); p = 0.048] and distant failure [HR substantial vs no: 4.4 (1.2-16.3); p = 0.027]. Both high-grade disease [HR 3 vs 1: 5.5 (1.2-25.6); p = 0.031] and extent of LVSI [HR substantial vs no: 4.4 (1.7-11.4); p = 0.002] predicted for worse disease-free survival. DISCUSSION: Substantial LVSI was the strongest adverse prognostic factor for pelvic and distant failure in this cohort of EEC patients receiving adjuvant VB alone, suggesting this subset may benefit from additional adjuvant therapy. This study underscores the importance of quantifying LVSI extent in EEC.

Implementation of high-dose-rate brachytherapy for prostatic carcinoma in an unshielded operating room facility.

PURPOSE: The purpose of the study was to describe our approach towards safe delivery of single-fraction high-dose-rate (HDR) brachytherapy (BT) boost in patients with prostate cancer in the setting of an unshielded operating room (OR). METHODS AND MATERIALS: A total of 95 patients received 15 Gy HDR BT boost. The procedure involved transrectal ultrasound-based catheter insertion and planning in the OR, after which the patient was moved to a shielded treatment room for radiation. This required three vital components: (1) an OR table capable of transporting the patient in lithotomy position, (2) robust motion management checks to ensure reproducibility of prostate and catheter positions in the treatment room before radiation delivery, (3) remote monitoring of patient vitals while under anesthesia, during the radiation. Initial viability of this approach was confirmed by assessing acute toxicities using the Common Terminology Criteria for Adverse Events v4.0 and American Urologic Association symptom scores. RESULTS: We found good stability in prostate and catheter position, with less than 1 mm shifts in each direction due to patient transfer. The median baseline American Urologic Association score was 7 (3-11), which increased to 12 (7-17) at 4 weeks and 9 (5-14) at 3 months (p = 0.003). Common Terminology Criteria for Adverse Events ≥ grade 2 genitourinary and gastrointestinal toxicities were experienced by 7% and 0% patients, respectively, at 3 months posttreatment completion. CONCLUSIONS: Single-fraction HDR prostate BT can be delivered safely in an unshielded OR facility with a distant shielded treatment room using rigorous motion management checks and supplementary procedural equipment.