Primary External Beam Radiotherapy Research Articles

Local salvage therapies in patients with radio-recurrent prostate cancer following external beam radiotherapy: a systematic review and meta-analysis.

To date, radio-recurrent prostate cancer (PCa) ranks as the fourth most common urological malignancy when considering the number of men with localized PCa who undergo radiation treatment and subsequently experience a biochemical recurrence. This systematic review aimed to summarize available evidence about the outcomes of local salvage strategies in patients with local PCa recurrence following primary external-beam radiation therapy (EBRT). We conducted a comprehensive bibliographic search on MEDLINE, Scopus, and Web of Science Core Collection databases in October 2023 to identify studies published in the last 20 years evaluating outcomes of local salvage procedures in patients with locally radio-recurrent PCa following EBRT. The meta-analysis was performed using ProMeta 3 software when two or more studies reported the same outcome. The effect size (ES) was estimated using rates reported with its 95% confidence interval (CI). Overall, 28 studies (6 prospective and 22 retrospective) including 1544 patients were included in the review. Two-year recurrence-free survival (RFS) was 84.0% (95% CI: 67.0-93.0%), 69.0% (95% CI: 42.0-87.0%), 58.0% (95% CI: 43.0-71.0%), and 45% (95% CI: 38.0-52.0%), for patients undergoing brachytherapy (BT), EBRT, Cryotherapy and High-Intensity Focused Ultrasound (HIFU), respectively. After salvage prostatectomy, RFS ranged from 75% to 78.5% at a median follow-up ranging from 18 to 35 months. Estimates for severe gastrointestinal toxicity were 2%, 3%, 3%, 4%, and 11% following cryotherapy, BT, HIFU, EBRT, and salvage radical prostatectomy, respectively. In patients who underwent EBRT as primary treatment, prostate salvage re-irradiation through BT or EBRT represents the modality providing the best balance between efficacy and safety. Unfortunately, due to the low level of evidence, strong recommendations regarding the choice of any of these techniques cannot be made.

Salvage Cryoablation for Recurrent Prostate Cancer Following Primary External Beam Radiotherapy or Primary Cryotherapy: A Propensity Score Matched Analysis of Mid-term Oncologic and Functional Outcomes.

Local prostate cancer recurrence following radiotherapy (XRT) or cryoablation (CRYO) may be addressed with salvage cryotherapy (SCT), although little is known about how the primary treatment modality affects SCT results. Oncologic and functional outcomes of patients who underwent SCT after primary XRT (XRT-SCT) or cryoablation (CRYO-SCT)were studied. Data was collected using the Duke Prostate Cancer database and the Cryo On-Line Data (COLD) registry. The primary outcome was biochemical progression-free survival (BPFS). Urinary incontinence, rectourethral fistula, and erectile dysfunction were secondary outcomes. The Kaplan-Meier log-rank test and univariable/multivariable Cox proportional hazards (CPH) models were utilized to evaluate BPFS between groups. 419 XRT-SCT and 63 CRYO-SCT patients met inclusion criteria, that was reduced to 63 patients in each cohort after propensity matching. There was no difference in BPFS at 2 and 5 years both before (P=.5 and P=.7) and after matching (P=.6 and P=.3). On multivariable CPH, BPFS was comparable between treatment groups (CRYO-SCT, HR=1.1, [0.2-2.2]). On the same analysis, BPFS was lower in D'Amico high-risk (HR 3.2, P < .01) and intermediate-risk (HR 1.95, P < .05) categories compared to low-risk. There was no significant difference in functional outcomes between cohorts. Following primary cryotherapy, salvage cryoablation provides comparable intermediate oncological outcomes and functional outcomes compared to primary radiotherapy.

Local salvage of radiorecurrent prostate cancer.

Locally recurrent prostate cancer following primary external beam radiotherapy without distant metastasis is a challenging problem, with no current consensus on the optimal management of these patients. Traditional whole-gland salvage treatments offered up to a 50% 5-year disease-free survival rate but with troubling levels of risk for significant complications. Recent progress in advanced imaging techniques has allowed a more accurate selection of patients with local-only recurrence and a selection of patients that may be suitable for newer partial-gland salvage treatments that may reduce late complications. This article reviews advances in patient selection and provides an overview of whole- and partial-gland salvage results from selected recent meta-analyses, multi-institutional series, and studies from centers of excellence for these treatment approaches. Salvage radical prostatectomy produces 5-year relapse-free survival (RFS) rates in the 50%-60% range with severe gastrointestinal (GI) toxicity in < 2% but severe genitourinary (GU) toxicity in 15%-23% of patients. The whole-gland options of high and low dose rate brachytherapy and stereotactic body radiation therapy appear to offer similar 5-year control rates, with low severe GU and GI toxicity rates of 4%-8% and <2%, respectively. Cryotherapy and high-intensity focused ultrasound (HIFU) offer similar 5-year RFS rates but carry significant risks for severe GU and GI toxicity in the range of 10%-27% and <2%, respectively. Early results of partial-gland salvage techniques in selected patients appear promising, with 3-year RFS rates of 48%-72% and rare grade 3 toxicity. It is important to understand the relative effectiveness and risks of the various treatment options to effectively counsel patients who face this distressing clinical situation. Whole-gland salvage options offer the possibility of long-term control but with significant risks of severe toxicity. Emerging data for the partial-gland salvage options in appropriately selected patients may offer hope of reasonable control rates with reduced severe toxicity.

The effect of lower urinary tract substructure doses on side effects of cervical cancer image-guided adaptive brachytherapy.

Image-Guided Adaptive Brachytherapy (IGABT) provides a survival advantage in locally advanced cervical cancer (LACC). Although side effects are seen less with this technique, dose parameters that cause urinary side effects are still questionable. We aim to investigate whether the radiotherapy doses of the lower urinary tract substructures (LUSS) affect the urinary system side effects (USSE) of cervical cancer external beam radiotherapy (EBRT) and the IGABT. LUSS (bladder, trigone, bladder neck, and urethra) doses were calculated in 40 patients diagnosed with LACC and receiving primary EBRT, IGABT, and concomitant chemotherapy. D0.1cc, D2cc, and D50% values were examined by contouring the bladder, trigone, bladder neck, and urethra from the intracavitary BT planning computed tomography (CT) images taken every 4 BT fractions, retrospectively. Besides, late USSE (urgency, dysuria (recurrent), frequency, obstruction, incontinence, hematuria, fistula, cystitis) were queried and categorized according to Common Toxicity Criteria for Adverse Events version 5.0. The Chi-square and Fisher's exact tests, Mann-Whitney U-test. For the whole study population, for both incontinence and dysuria, trigone (D50%), urethra (D50%, D0.1cc,), and bladder neck (D50%, D0.1cc, D2cc) volume and hot spot doses remained significant. For cystitis, urethra (D50%, D0.1cc,) and bladder neck doses (D0.1cc, D50%, D2cc) are worth investigating. Although USSE is less common in the intensity-modulated radiation therapy and IGABT era, it may be meaningful to take the doses of LUSS into account when planning IGABT. In addition, delineation of LUSS using only CT seems feasible. More proof is needed to determine delineation technique and dose constraints for LUSS for IGABT.

Identifying disparities in brachytherapy delivery for locally advanced cervical cancer

IntroductionThe standard of care for locally advanced cervical cancer is concurrent chemotherapy and external beam radiation therapy (EBRT) followed by a brachytherapy boost. Some studies show a decreased usage of brachytherapy in cervical cancer patients despite the standard of care and known survival advantage. This study aims to characterize the utilization of brachytherapy in Oregon and identify where disparities in treatment may exist. MethodsThe Oregon State Cancer Registry database was used to identify patients diagnosed with FIGO Stage IB2-IVB cervical cancer between 2007 and 2016. Patients who received initial EBRT were categorized by whether they received brachytherapy boost or not. Age at diagnosis, county of patient residence, rural-urban status of the county, race/ethnicity, and insurance payer were studied using multivariable logistic regression to identify possible underserved populations. Survival data was compared using a Cox proportional hazard survival model. Results401 patients who received primary EBRT for FIGO stage IB2-IVB cervical cancer were identified in the 10-year span. Breakdown by stage is: 16% stage IB2, 23.9% stage II, 37.4% stage III, and 22.7% stage IV. Of those, 154 (38.4%) received brachytherapy boost treatment, 75 (18.7%) received a different boost modality, and 42.9% received no boost. Stage IV (p = 0.001) and uninsured patients (p = 0.04) were significantly less likely to receive brachytherapy. Older age was also associated with decreased brachytherapy usage, as each additional year of life decreased brachytherapy receipt by 1.8% (p = 0.04). Native American and Pacific Islander patients were the only group significantly more likely to receive brachytherapy (p=0.003). There was no significant difference in the rate of brachytherapy boost identified based on urban/rural status of the county (p = 0.63 to 0.69), other racial/ethnic categories (p = 0.66 to 0.80), or among the other stages (p=0.45 to 0.63). In Cox proportional hazard survival analysis, patients that received brachytherapy showed a 42% reduction in risk of cancer specific mortality, though this did not reach the predetermined level of statistical significance (p = 0.057). ConclusionsThe brachytherapy boost rate among locally advanced cervical cancer patients was 38.4%. The data also indicated a likely reduction in cancer specific mortality in patients receiving brachytherapy. Older patients, stage IV patients, and uninsured patients were less likely to receive brachytherapy. Given the low overall brachytherapy usage, these data indicate access and delivery of brachytherapy care needs to be improved across the state. The increased brachytherapy use in the American Indian and Pacific Islander patient population should be further studied to identify facilitators to treatment completion and potentially extrapolate to other groups.

PD15-05 LONG-TERM RATES OF BIOCHEMICAL RECURRENCE AFTER PRIMARY EXTERNAL BEAM RADIATION THERAPY FOR PROSTATE CANCER

You have accessJournal of UrologyCME1 Apr 2023PD15-05 LONG-TERM RATES OF BIOCHEMICAL RECURRENCE AFTER PRIMARY EXTERNAL BEAM RADIATION THERAPY FOR PROSTATE CANCER Domenique Escobar, Lufan Wang, Jasmin Banton, Janet Cowan, Samuel Washington, Osama Mohamad, Mani Menon, and Peter Carroll Domenique EscobarDomenique Escobar More articles by this author , Lufan WangLufan Wang More articles by this author , Jasmin BantonJasmin Banton More articles by this author , Janet CowanJanet Cowan More articles by this author , Samuel WashingtonSamuel Washington More articles by this author , Osama MohamadOsama Mohamad More articles by this author , Mani MenonMani Menon More articles by this author , and Peter CarrollPeter Carroll More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003262.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Radiation therapy is a common form of treatment for men with prostate cancer. Biochemical recurrence (BCR) is defined according to the ASTRO Phoenix definition of PSA nadir +2. We sought to characterize long term rates of biochemical recurrence in a large, well-characterized and well-followed cohort of men treated with primary external beam radiation therapy (EBRT). METHODS: Patients were enrolled in CaPSURE, a national registry of men diagnosed with prostate cancer, from 1995 - 2017 with clinically localized prostate cancer (cN0M0/X, PSA≤50) and treated with primary EBRT. Cancer risk was defined by NCCN criteria. Cox proportional hazards regressions were used to assess associations between patient characteristics and BCR was defined by PSA nadir +2. RESULTS: 1193 patients were included. Mean age at diagnosis was 70 (SD 6.82), median PSA at diagnosis was 7.5 and mean number of follow up PSA tests was 5. Overall rates of BCR were 17.4% at 5 years and 39.4% at 10 years. NCCN clinical risk was significantly associated with rates of BCR with high-risk patients having the highest rates of recurrence, followed by intermediate- and low-risk groups (61.5%, 36.4% and 28.5% respectively at 10 years, log-rank p<0.01). NCCN high vs low clinical risk was significantly associated with likelihood of BCR (HR 4.8, CI 2.5–9.2). Rates of salvage treatment were 16% at 5 years and 19% at 10 years and these were also significantly associated with NCCN high vs low clinical risk (HR 3.7, CI 2.3–6) and concurrent ADT (HR 1.83, CI 1.2–2.7). Overall rates of bone metastases were 2.6% at 5 years and 4% at 10 years. Overall prostate cancer specific mortality was 3% at 5 years and 7% at 10 years. CONCLUSIONS: In this analysis, rates of BCR were fairly high and consistent with published RTOG studies, but rates of salvage treatment were relatively low in comparison, indicating that not all patients who recur need, are offered or want treatment. The limitations of this analysis include incomplete information on radiation dose and field size. The strengths of this analysis include the size of the cohort and the length of follow-up. Furthermore, as this cohort largely represents treatment in community settings, the results may be broadly applicable. Source of Funding: UCSF Goldberg-Benioff Program in Translational Cancer Biology © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e420 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Domenique Escobar More articles by this author Lufan Wang More articles by this author Jasmin Banton More articles by this author Janet Cowan More articles by this author Samuel Washington More articles by this author Osama Mohamad More articles by this author Mani Menon More articles by this author Peter Carroll More articles by this author Expand All Advertisement PDF downloadLoading ...

MP73-06 OUTCOMES OF SALVAGE CRYOTHERAPY FOR BIOCHEMICAL RECURRENCE FOLLOWING PRIMARY RADIOTHERAPY IN THE MANAGEMENT OF PROSTATE CANCER - 14-YEARS SINGLE INSTITUTION EXPERIENCE

You have accessJournal of UrologyCME1 Apr 2023MP73-06 OUTCOMES OF SALVAGE CRYOTHERAPY FOR BIOCHEMICAL RECURRENCE FOLLOWING PRIMARY RADIOTHERAPY IN THE MANAGEMENT OF PROSTATE CANCER - 14-YEARS SINGLE INSTITUTION EXPERIENCE Gregory Mansour, Andrew Wang, and Robert Given Gregory MansourGregory Mansour More articles by this author , Andrew WangAndrew Wang More articles by this author , and Robert GivenRobert Given More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003341.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Salvage cryotherapy of the prostate remains a treatment option for biochemical recurrence (BCR) following either radiotherapy or other local ablative therapies of prostate cancer. Previous studies have assessed long-term oncologic results to include overall disease survival in addition to freedom from starting ADT. We aim to assess oncologic outcomes in addition to de novo stricture, fistula, urinary incontinence, and erectile dysfunction rates. METHODS: We retrospectively reviewed all men who underwent salvage cryotherapy following external beam radiation therapy (EBRT), proton beam therapy, primary cryotherapy, and brachytherapy at our institution from 2005 through 2019. Functional and oncologic outcomes were assessed. Biochemical recurrence-free survival was defined based on a combination of the Phoenix and Astro criteria and analyzed using Kaplan-Meier statistics. RESULTS: Of the total 85 patients included, 71 had primary EBRT, 9 had brachytherapy, 3 had combined EBRT and brachytherapy, and 2 had proton beam therapy. All patients had negative staging workups prior to salvage therapy. Recto-urethral fistulas occurred in 2 patients (2.3%), 21 patients (24.4%) developed urethral strictures, and 23 patients (26.7%) reported de novo incontinence requiring pads. 5- year overall biochemical free survival was 49%. A total of 53% of subjects had biochemical recurrence with a mean time of 39 months after salvage treatment. Overall cancer specific survival was 86% and metastasis free survival was 77.9%. There was not a statistically significant correlation identified between pretreatment PSA and timing to BCR R2=0.05 p=0.129. One patient did not have a PSA response after salvage cryotherapy and went on to develop metastatic disease. CONCLUSIONS: Salvage cryotherapy remains one of the few potentially curative interventions following primary radiotherapy for prostate cancer. This study highlights the necessity for patient counseling given the side effect profile. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1036 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Gregory Mansour More articles by this author Andrew Wang More articles by this author Robert Given More articles by this author Expand All Advertisement PDF downloadLoading ...

Long-term rates of biochemical recurrence after primary external beam radiation therapy (EBRT) for prostate cancer.

393 Background: Radiation therapy is a common form of treatment for men with prostate cancer. Biochemical recurrence (BCR) is most commonly defined using the Phoenix definition of PSA nadir + 2. We sought to characterize long term rates of biochemical recurrence in a large, well-characterized and well-followed cohort of men treated with primary EBRT. Methods: Patients enrolled in CaPSURE, a national registry of men diagnosed with prostate cancer, from 1995 - 2017 with clinically localized prostate cancer (cN0M0/X, PSA&lt;=50) treated with primary EBRT were included. Cancer risk was defined by NCCN criteria. Cox proportional hazards regressions were used to assess associations between patient characteristics and BCR as defined by PSA nadir + 2. Results: 1193 patients were included. Mean age at diagnosis was 70 (SD 6.82), median PSA at diagnosis was 7.6 and mean number of follow up PSA tests was 5. Overall rates of BCR were 17.4% at 5 years and 39.4% at 10 years. Rates of BCR were significantly associated with NCCN risk with high-risk patients having the highest rates of recurrence, followed by intermediate- and low-risk groups (61.5%, 36.4% and 28.5% respectively at 10 years). NCCN high vs low clinical risk was significantly associated with likelihood of BCR (HR 4.8, CI 2.5 – 9.2). Rates of salvage treatment, usually ADT, were 16% at 5 years and 19% at 10 years and these were also significantly associated with NCCN high vs low clinical risk (HR 3.7, CI 2.3 – 6) and concurrent ADT (HR 1.83, CI 1.2 – 2.7). Overall rates of bone metastases were 2.6% at 5 years and 4% at 10 years. Overall prostate cancer specific mortality was 3% at 5 years and 7% at 10 years. Conclusions: In this analysis, rates of BCR were fairly high and consistent with published RTOG studies, but rates of salvage treatment were relatively low in comparison, indicating that not all patients who recur need, are offered or want treatment. The limitations of this analysis include incomplete information on radiation dose and field size. The strengths of this analysis include the size of the cohort and the length of follow-up. Furthermore, as this cohort largely represents treatment in community settings, the results may be broadly applicable.

Sexual function after primary external beam radiation therapy (EBRT) for prostate cancer in a large cohort of men with long-term follow-up.

346 Background: Clinically localized prostate cancer can be treated with prostatectomy, radiation or focal therapy, with known impacts on sexual function. We sought to characterize long term sexual function in a large cohort of men treated with primary EBRT and to differentiate between those who have high vs low sexual function scores at baseline. Methods: Patients enrolled in CaPSURE, a national registry of men diagnosed with prostate cancer, from 1995 - 2017 with clinically localized prostate cancer (cN0M0/X, PSA &lt; = 50) and treated with primary EBRT were included. Sexual function (SF) was self-reported using the UCLA Prostate Cancer Index (PCI). We performed repeated measures mixed models to evaluate SF after EBRT, stratified by baseline SF and adjusted for age, BMI, comorbidities, smoking, clinical risk, receipt of brachytherapy and/or hormonal therapy, and type of clinical site. Results: 1193 patients were included for analysis. Mean age was 70, mean number of comorbidities was 2, and median PSA was 7.5 at diagnosis. Baseline PCI scores were available for 43% of the cohort (data not collected before 1998). The mean PCI score was 38 out of 100 at baseline and after EBRT, declined gradually to 16 by 10 years. When only those men with good SF at baseline were assessed (scores 80 – 100), the initial rate of decline was more severe, but the nadir in this group was higher than those with lower baseline scores. Unadjusted mean PCI scores showed a similar decline amongst both groups, although those with good baseline SF consistently had better scores. 63% of patients were treated for erectile dysfunction (PDE5 inhibitors, intracavernosal injections or both), 13% of whom started therapy before EBRT. In the repeated measures mixed models analysis, we found that SF changed significantly over time and scores differed significantly by age, comorbidities, baseline SF, receipt of brachytherapy boost and concurrent ADT. Conclusions: SF after EBRT declines and persists. The most affected are those who had better PCI scores at baseline, although their overall PCI scores are consistently higher compared to those with baseline scores less than 80. Among both groups however, there was a similar decline that was statistically significant.

The Safety and Efficacy of Salvage Stereotactic Radiation Therapy in Patients with Intraprostatic Tumor Recurrence After Previous External Radiation Therapy: Phase 1 Results from the GETUG-AFU 31 Study

BackgroundThere is no consensus on the best local salvage treatment for prostate cancer recurrence after primary external beam radiotherapy. Prospective data on stereotactic body radiation therapy (SBRT) are very scarce. ObjectiveTo determine the optimal dose regimen for salvage SBRT. Design, setting, and participantsThe present report concerns the phase 1 part of the GETUG-AFU 31 multicenter open-label study. The main inclusion criteria were histologically proven biochemical recurrence, clinical stage T1-T2 upon relapse, multiparametric magnetic resonance imaging data, prostate-specific antigen (PSA) level ≤10 ng/ml prior to salvage SBRT, PSA doubling time >10 mo, and an International Prostate Symptom Score of ≤12. InterventionFive or six fractions of 6 Gy were delivered using focal SBRT. Outcome measurements and statistical analysisDose-limiting toxicity (DLT) was defined as grade ≥3 gastrointestinal or genitourinary tract toxicity, or any grade 4 toxicity (according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03) occurring in the first 18 wk following treatment initiation. A time-to-event continual reassessment method was used to select the dose regimen. Results and limitationsTwenty-one patients were treated (median [interquartile range] age: 76.8 yr [72.2–80.8]), including 12 at 6 × 6 dose level. No DLT was observed. The acute grade 2 genitourinary tract toxicity rate was 19%. With a median follow-up of 12.3 mo, the estimated cumulative incidence of late grade 2 genitourinary toxicity was 41.2% (95% confidence interval: 18.1–63.1%). No grade >2 genitourinary toxicity and no grade ≥2 gastrointestinal toxicity were reported. All treated patients were alive and relapse free at the last follow-up. ConclusionsA 6 × 6 Gy dose regimen was selected for our phase 2 study of salvage SBRT. With a short follow-up period, the level of toxicity appears to be acceptable. Patient summaryThere is no consensus on the best local treatment for patients with local relapse after radiotherapy for prostate cancer. Prospective data are very scarce. Our early phase trial allowed us to recommend six fractions of 6 Gy using high-precision radiotherapy for further studies.

Radiation to all macroscopic sites of tumor permits greater systemic antitumor response to in situ vaccination

BackgroundThe antitumor effects of external beam radiation therapy (EBRT) are mediated, in part, by an immune response. We have reported that a single fraction of 12 Gy EBRT combined with...

CTNI-51. FEASIBILITY AND SAFETY OF NEUROSURGICAL RESECTION AND INTRA-OPERATIVE RADIATION THERAPY USING THE XOFT AXXENT ELECTRONIC BRACHYTHERAPY SYSTEM AND BEVACIZUMAB IN RECURRENT GLIOBLASTOMA

Abstract Glioblastoma (GBM) is the most common and aggressive primary brain tumor. External beam radiation therapy (EBRT) is widely recognized as an effective treatment for primary GBM. EBRT applied after GBM resection is associated with an increase in overall survival. Beyond upfront therapy with radiation and temozolomide chemotherapy, there is no standard therapy that has been proven effective. Re-irradiation with ERBT is minimally effective and with significant comorbidities. Our study uses IORT at the time of re-resection in patients who have recurrent, operable GBM after failure of who received primary EBRT and temozolamide in their first course of treatment. IORT allows the delivery of a large effective radiation dose applied directly to the tumor bed at the time of resection. This affords direct radiation to be delivered to the micro- and macroscopic tumor remnants in the vicinity of the resection cavity immediately following gross resection. In contrast, the more distant, surrounding brain tissue does not receive high radiation exposure. This Phase II study continues to accrue subjects with the primary endpoint of overall survival and several secondary endpoints that includes progression free survival, quality of life, and adverse events/safety. To date, five patients have been treated on this protocol. The technical feasibility and safety of administering intraoperative radiation with the Xoft System has been established in this cohort. Preliminary GLIOX Trial findings demonstrate the safety and feasibility of using the Xoft Axxent® Electronic Brachytherapy System to administer intracranial radiation during resection of recurrent glioblastomas. We will report new and expansive study results to include these early findings.

Salvage external beam radiotherapy after HIFU failure in localized prostate cancer: A single institution experience

High-intensity focused ultrasound (HIFU) remains investigational as primary treatment for localized prostate cancer but is sometimes offered to select patients. At HIFU failure, data guiding salvage treatment is limited to small retrospective series with short follow-up. We evaluated our institutional experience using salvage radiation therapy (SRT) after HIFU failure. We conducted a retrospective analysis of patients with local failure post-HIFU who received salvage image-guided external beam radiation therapy (EBRT) delivered via intensity-modulated radiotherapy (IMRT). Our primary endpoint was biochemical failure-free survival (bFFS) defined as prostate-specific antigen (PSA) nadir + 2 ng/mL. Secondary endpoints included metastasis-free survival (MFS) and overall survival (OS). Endpoints were evaluated using Kaplan-Meier analysis. From 2013 to 2018, 12 out of 96 patients treated with primary HIFU received SRT via conventional or moderate hypofractionation. Median time from HIFU to SRT was 13.5 months. Seven patients had stage migration to high-risk disease at the time of SRT. Mean PSA prior to SRT was 8.2ug/L and mean nadir post-SRT was 1.2ug/L. Acute International Prostate Symptom Score (IPSS) as well as International Index of Erectile Dysfunction (IIEF) scores were similar to baseline (p = 0.5 and 0.1, respectively). Late toxicities were comparable to those reported after primary EBRT for localized prostate cancer. At a median follow-up of 46 months, the OS was 100%. The 5-year bFFS and MFS were both 83.3%. To our knowledge, we report one of the largest series on contemporary SRT post HIFU failure. We show that SRT is feasible, effective and carries no additional acute or delayed toxicity.

GSOR15 Presentation Time: 11:40 AM: Underutilization of Brachytherapy: A Retrospective State Level Analysis of Brachytherapy Delivery in Locally Advanced Cervical Cancer

<h3>Purpose</h3> The standard of care for locally advanced cervical cancer is concurrent chemotherapy and external beam radiation therapy (EBRT) followed by a brachytherapy boost. Decreased rate of brachytherapy in cervical cancer patients has shown a declining survival for these patients. This study aims to characterize the utilization of brachytherapy in Oregon in order to better understand how care delivery can be improved. <h3>Materials and Methods</h3> The Oregon State Cancer Registry database was used to identify patients diagnosed with FIGO 2008 Stage IB2-IVB cervical cancer between 2007 and 2016. Patients who received initial EBRT were categorized by whether they received brachytherapy boost or not. Age at diagnosis, county, rural/urban status of the county, race/ethnicity, and insurance payer were studied using multivariable logistic regression to identify possible underserved populations. Survival data was compared using a Cox proportional hazard survival model. Changes in brachytherapy use over time were also examined by grouping patients by year of diagnosis and comparing the rates of brachytherapy utilization over the duration of the study. <h3>Results</h3> 401 patients who received primary EBRT for FIGO stage IB2-IVB cervical cancer were identified in the 10-year span. Breakdown by stage is: 16% stage IB2, 23.9% stage II, 37.4% stage III, and 22.7% stage IV. Of those, 154 (38.4%) received brachytherapy boost treatment, 75 (18.7%) received a different boost modality, and 172 (42.9%) received no boost. Stage IV (p=0.001) and uninsured patients (p=0.04) were significantly less likely to receive brachytherapy. Older age was also associated with decreased brachytherapy usage, as each additional year of life correlated with a decreased likelihood of brachytherapy receipt of 1.8% (p=0.04). Native American and Pacific Islander patients were the only group significantly more likely to receive brachytherapy (p=0.003). There was no significant difference in the rate of brachytherapy boost based on urban/rural status of the county (p=0.63 to 0.69), other racial/ethnic categories (p=0.66 to 0.80), or among the other stages (p=0.45 to 0.63). In Cox proportional hazard survival analysis, patients that received brachytherapy showed a 42% reduction in risk of cancer specific mortality, though this did not reach the level of statistical significance (p=0.057). In terms of brachytherapy utilization by year, no definitive trend was shown. Yearly rates varied from 25% to 52%, with a dip in utilization in 2013 and 2014 at around 30% before a jump in utilization in 2015 and 2016 to around 50%. <h3>Conclusions</h3> The brachytherapy boost rates among locally advanced cervical cancer patients were 38.4%. Though not statistically significant, a reduction in cancer specific mortality in patients receiving brachytherapy by 42% was seen. Older patients, stage IV patients, and uninsured patients were less likely to receive brachytherapy. Given the low overall brachytherapy usage, these data may indicate barriers to access and delivery of brachytherapy care. The increased brachytherapy use in the American Indian and Pacific Islander patient population should be further studied to identify facilitators to treatment completion and potentially extrapolate to other groups.

The 17-Gene Genomic Prostate Score Test Is Prognostic for Outcomes After Primary External Beam Radiation Therapy in Men With Clinically Localized Prostate Cancer

The Oncotype DX Genomic Prostate Score® (GPS™) assay has been validated as a strong prognostic indicator of adverse pathology, biochemical recurrence, distant metastasis (DM), and prostate cancer (PCa)-related death (PCD) in men with localized PCa after radical prostatectomy. However, it has yet to be tested in men undergoing external beam radiation therapy (EBRT), for whom assessing PCa progression risk could inform decisions on treatment intensity. We analyzed whether GPS results are associated with time to biochemical failure (BCF), DM, and PCD after EBRT in men with localized PCa and whether the association is modified by race. We conducted a retrospective study of men with localized PCa treated with EBRT at the [ANONYMIZED FOR REVIEW] from 2000 to 2016. Study endpoints were time to BCF per the Phoenix criteria, DM, and PCD. The association of GPS results, per 20-unit increase or dichotomous variable (0-40 versus 41-100), was evaluated with each endpoint using univariable and multivariable Cox proportional hazards models. Results were then stratified by race. A total of 238 patients (69% Black) met eligibility criteria. Median follow-up for patients who did not experience BCF was 7.6 years. GPS results per 20-unit increase were significantly associated with BCF (hazard ratio (HR) 3.62; 95% CI 2.59, 5.02), DM (HR 4.48; 2.75, 7.38), and PCD (HR 5.36; 3.06, 9.76) in univariable analysis. GPS results remained significant in multivariable models adjusted for baseline clinical and pathological factors, with HRs similar to the univariable analysis. There was no significant interaction between the GPS assay and race (p=0.923). HRs for BCF were similar in Black men (3.88; 2.40, 6.24) versus non-Black men (4.01; 2.42, 6.45). Among men treated with EBRT, the GPS assay is a strong, independent prognostic indicator of time to BCF, DM and PCD, and performs similarly in Black and non-Black men.

Identifying Disparities in Cervical Cancer Brachytherapy Delivery

<h3>Purpose/Objective(s)</h3> The standard of care for locally advanced cervical cancer is concurrent chemotherapy and external beam radiation therapy (EBRT) followed by a brachytherapy boost. Some studies show a decreased usage of brachytherapy in cervical cancer patients despite the standard of care and known survival advantage. This study aims to characterize the utilization of brachytherapy in Oregon and identify where disparities in treatment may exist. <h3>Materials/Methods</h3> The Oregon State Cancer Registry database was used to identify patients diagnosed with FIGO Stage IB2-IVB cervical cancer between 2007 and 2016. Patients who received initial EBRT were categorized by whether they received brachytherapy boost or not. Age at diagnosis, county, rural/urban status of the county, race/ethnicity, and insurance payer were studied using multivariable logistic regression to identify possible underserved populations. Survival data was compared using a Cox proportional hazard survival model. <h3>Results</h3> 401 patients who received primary EBRT for FIGO stage IB2-IVB cervical cancer were identified in the 10-year span. Breakdown by stage is: 16% Stage IB2, 23.9% stage II, 37.4% stage III, and 22.7% stage IV. Of those, 154 (38.4%) received brachytherapy boost treatment, 75 (18.7%) received a different boost modality, and 42.9% received no boost. Stage IV (p=0.001) and uninsured patients (p=0.04) were significantly less likely to receive brachytherapy. Older age was also associated with decreased brachytherapy usage, as each additional year of life decreased brachytherapy receipt by 1.8% (p=0.04). Native American and Pacific Islander patients were the only group significantly more likely to receive brachytherapy (p=0.003). There was no significant difference in the rate of brachytherapy boost identified based on urban/rural status of the county (p=0.63 to 0.69), other racial/ethnic categories (p=0.66 to 0.80), or among the other stages (p=0.45 to 0.63). In Cox proportional hazard survival analysis, patients that received brachytherapy showed a 42% reduction in risk of cancer specific mortality, though this did not reach the level of statistical significance (p=0.057). <h3>Conclusion</h3> The brachytherapy boost rates among locally advanced cervical cancer patients were 38.4%, similar to national averages. Though not statistically significant, data also showed a reduction in cancer specific mortality in patients receiving brachytherapy. Older patients, stage IV patients, and uninsured patients were less likely to receive brachytherapy. Given the low overall brachytherapy usage, these data indicate access and delivery of brachytherapy care needs to be improved across the state. The increased brachytherapy use in the American Indian and Pacific Islander patient population should be further studied to identify facilitators to treatment completion and potentially extrapolate to other groups.

Predicting Local Failure after Partial Prostate Re-Irradiation Using a Dosiomic-Based Machine Learning Model.

The aim of this study is to predict local failure after partial prostate re-irradiation for the treatment of isolated locally recurrent prostate cancer by using a machine learning classifier based on radiomic features from pre-treatment computed tomography (CT), positron-emission tomography (PET) and biological effective dose distribution (BED) of the radiotherapy plan. The analysis was conducted on a monocentric dataset of 43 patients with evidence of isolated intraprostatic recurrence of prostate cancer after primary external beam radiotherapy. All patients received partial prostate re-irradiation delivered by volumetric modulated arc therapy. The gross tumor volume (GTV) of each patient was manually contoured from planning CT, choline-PET and dose maps. An ensemble machine learning pipeline including unbalanced data correction and feature selection was trained using the radiomic and dosiomic features as input for predicting occurrence of local failure. The model performance was assessed using sensitivity, specificity, accuracy and area under receiver operating characteristic curves of the score function in 10-fold cross validation repeated 100 times. Local failure was observed in 13 patients (30%), with a median time to recurrence of 36.7 months (range = 6.1–102.4 months). A four variables ensemble machine learning model resulted in accuracy of 0.62 and AUC 0.65. According to our results, a dosiomic machine learning classifier can predict local failure after partial prostate re-irradiation.

The role of external beam radiation therapy in the management of thyroid carcinomas: A retrospective study in Iran Cancer Institute.

Thyroid cancers are histologically classified into three types; differentiated thyroid carcinoma (DTC), medullary thyroid carcinoma (MTC), and anaplastic thyroid carcinoma (ATC). Among the several therapeutic strategies for treatment and management of thyroid cancer, surgical resection in combination with radioactive iodine therapy (RAI) is indicated for moderate to high-risk differentiated thyroid cancer (DTC) patients- according to current guidelines. However, external radiation therapy (EBRT) can be a viable alternative treatment option for these patients and scarce evidence is available regarding the efficacy and effectiveness of EBRT on thyroid cancer. This study aims at evaluating the role of EBRT in the management of thyroid carcinomas. In this retrospective cohort study, the records of 59 patients with thyroid cancer were accessed who were treated by EBRT from 2008 to 2016. The indications for EBRT included unresectable primary (definitive) or loco-regional recurrences (salvage) not suitable for RAI, palliation for local disease or metastatic foci (palliative), and the adjuvant treatment for suspected residual disease following resection. Progression-free survival (PFS) and overall survival (OS) were calculated for different types of cancer. PFS was measured from the start of EBRT to the last uneventful follow-up, recurrence, or death. Kaplan-Meier model was used for the survival analysis. Fifty-nine patients were evaluated. The histopathology of the tumors was differentiated and poorly-differentiated, medullary and anaplastic thyroid carcinomas in 22 and 6, 15 and 16 patients, respectively. Twenty-seven patients received external beam radiotherapy (EBRT) as adjuvant therapy and 18 of the cases as palliative therapy while the remaining received salvage or definitive primary EBRT. The stage of patients' cancer was as follows: stage II in 3 and III in 1, IVA in 18 and IVB in 18 and IVC in 19. Stage-based median overall survival was 26 months for IVA, 44 for IVB, and 29 for IVC. The median PFS was 18, 22 and 21 months for stages IVA, IVB and IVC, respectively. Based on our findings, EBRT may still play a role in the management of patients with thyroid carcinoma and should be considered in the armamentarium against thyroid cancers.

Pelvic organ prolapse and vaginal cancer: A systematic literature review.

Primary vaginal cancer is a rare gynecologic malignancy. Few cases describing the concurrence of a vaginal tumor with advanced genital prolapse are reported in the literature and there is no consensus on optimal treatment. To investigate available evidence on presentation, treatment, and outcomes of these concurrent conditions. We performed a systematic search of literature indexed on PubMed, Scopus, ISI Web of Science, and Cochrane using a combination of keywords and text words represented by "pelvic organ prolapse", "genital prolapse", and "vaginal cancer", "vaginal carcinoma". No article type restrictions were applied. Twenty-one studies (case reports and two small case series) were incorporated into the review process, for a total of 27 patients. Management usually involved surgery or primary external beam radiation therapy. External beam radiation therapy was reported to be highly associated with the development of vesicovaginal fistula. A surgical approach was the treatment of choice in most cases. Exclusive interstitial brachytherapy was rarely performed. A multidisciplinary approach considering risks and benefits is of the utmost importance to provide counseling and tailor treatment strategy in these complex cases.

Incidence of genitourinary complications following radiation therapy for localised prostate cancer

PurposeStudies of genitourinary toxicity following radiotherapy for prostate cancer are mainly from high volume single institutions and the incidence and burden of treatment remain uncertain. Hence we determine the cumulative incidence of treatment-related genitourinary toxicity in patients with localised prostate cancer treated with primary external beam radiotherapy (EBRT) at a state population level.MethodsWe analysed data from a prospective population-based cohort, including hospital admission and cancer registry data, for men with localised prostate cancer who underwent primary EBRT without nodal irradiation between 1998 and 2019 in South Australia. The 10-year cumulative incidence of genitourinary toxicity requiring hospitalisation or procedures was determined. Clinical predictors of toxicity and the volume of admissions, non-operative, minor operative and major operative procedures were determined.ResultsAll the included patients (n = 3350) had EBRT, with a median (IQR) of 74 Gy (70–78) in 37 fractions (35–39). The 10-year cumulative incidence of was 28.4% (95% CI 26.3–30.6) with a total of 2545 hospital admissions, including 1040 (41%) emergency and 1893 (74%) readmissions. The 10-year cumulative incidence of patients in this cohort requiring a urological operative procedure was 18% (95% CI 16.1–19.9), with a total of 106 (4.2%) non-operative, 1044 (41%) minor operative and 57 (2.2%) major operative urological procedures.ConclusionsGenitourinary toxicity after radiotherapy for prostate cancer is common. Although there continue to be advancements in radiotherapy techniques, patients and physicians should be aware of the risk of late toxicity when considering EBRT.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00345-022-04124-x.