Evaluating outcomes and toxicities for a newly implemented MRI-based brachytherapy program for cervical cancer.

OBJECTIVE: We report an updated analysis of the outcomes and toxicities of MRI-based brachytherapy for locally advanced cervical cancer from a U.S. academic center. METHODS: A retrospective review was performed on patients treated with MRI-based brachytherapy for cervical cancer. EBRT was standardly 45 Gy in 25 fractions with weekly cisplatin. MRI was performed with the brachytherapy applicator in situ. Dose specification was most commonly 7 Gy for 4 fractions with optimization aim of D90 HR-CTV EQD2 of 85-95 Gyα/ß=10 Gy in 2 implants each delivering 2 fractions. RESULTS: Ninety-eight patients were included with median follow up of 24.5 months (IQR 11.9-39.8). Stage IIIA-IVB accounted for 31.6% of cases. Dosimetry results include median GTV D98 of 101.0 Gy (IQR 93.3-118.8) and HR-CTV D90 of 89 Gy (IQR 86.1-90.6). Median D2cc bladder, rectum, sigmoid, and bowel doses were 82.1 Gy (IQR 75.9-88.0), 65.9 Gy (IQR 59.6-71.2), 65.1 Gy (IQR 57.7-69.6), and 55 Gy (IQR 48.9-60.9). Chronic grade 3+ toxicities were seen in the bladder (8.2%), rectosigmoid (4.1%), and vagina (1.0%). Three-year LC, PFS, and OS were estimated to be 84%, 61.7%, and 76.1%, respectively. CONCLUSION: MRI-based brachytherapy demonstrates excellent local control and acceptable rates of high-grade morbidity. These results are possible in our population with relatively large volume primary tumors and extensive local disease.

Prevalence of trauma history and symptoms in patients who have received vaginal brachytherapy as part of their endometrial cancer treatment.

OBJECTIVE: Vaginal brachytherapy (VBT) is an essential component of curative intent treatment for many patients with endometrial cancer. The prevalence of trauma history in this population is unknown and important to understand considering VBT requires patients to have an instrument vaginally inserted while in the vulnerable lithotomy position. We aim to identify patients treated with intracavitary VBT and collect survey data to assess trauma endpoints. METHODS: We retrospectively identified patients with endometrial cancer who underwent intracavitary VBT at our institution between 01/2017 and 08/2022. Patients were mailed and/or electronically mailed a survey that included demographics, psychosocial background, and validated trauma surveys to be filled out as they relate to their trauma experiences prior to VBT and again considering any trauma symptomatology related to VBT. Electronic medical record review was performed. Descriptive statistics as well as multivariate analysis were performed. RESULTS: 206 patients met inclusion criteria, 66 (32.1%) of whom returned the survey and were included for analysis. Thirty-two percent of patients self-reported a personal history of any prior mental health diagnosis. Eighty-eight percent of patients screened positive for a history of trauma exposure, 23% endorsed symptoms of PTSD related to their VBT experience, and 5% screened positive for a likely PTSD diagnosis from VBT. CONCLUSION: A majority of included patients had a history of trauma exposure prior to VBT. In a subset of patients, VBT re-induced trauma and was considered to be an independent traumatic event. This study highlights the importance of practicing trauma informed care, particularly in this patient population.

Bombarding Oligoprogression: Oncologic Outcomes After Radiation to Patients With Oligoprogressive Non-Small Cell Lung Cancer on Maintenance Systemic Therapy.

OBJECTIVES: This study aims to evaluate the efficacy and toxicity of radiotherapy (RT) to oligoprogressive metastatic non-small cell lung cancer (NSCLC). METHODS: This is a retrospective analysis of 23 patients with metastatic NSCLC on maintenance systemic therapy, developed oligoprogression (1 to 5 sites), and all oligoprogressive sites amenable to and treated with RT. The primary endpoints included progression-free survival (PFS) and median time to start next-line therapy (MTT). Kaplan-Meier survival analysis and log-rank testing were performed using R-Studio software. RESULTS: Twenty-three patients met the inclusion criteria. The median overall survival for the entire cohort was 31.3 months (interquartile range [IQR]: 17.86 to 45.4). The median event-free survival for the entire cohort was 8.3 months (IQR: 2.7 to 12). Patients with no prior radiation had longer median event-free survival of 11.9 months (IQR: 8.4 to 18.2) compared with patients with a history of prior radiation at 4.1 months (IQR: 2.7 to 12; P = 0.041). The local control rate for the treated lesions was 97.5%. At 12 months follow-up, 6 (43%) of 14 living patients maintained systemic therapy without initiating next-line therapy. The median PFS for the entire cohort was 8.4 months (IQR: 4.1 to 17.5). Patients who did not receive prior radiation had longer median PFS of 11.9 months (IQR: 8.4 to 18.2) compared with patients who received prior radiation 6.2 months (IQR: 2.7 to 8.5; P = 0.018). Two patients (9%) had grade 3 chronic toxicity related to RT and were medically managed. CONCLUSION: We identified that in patients with oligoprogressive metastatic NSCLC, targeted RT to all progressive sites yielded high LC and favorable rates of PFS and MTT.

F-SHARP: a Phase I/II trial of focal salvage high-dose-rate brachytherapy for Radiorecurrent prostate cancer.

BACKGROUND: Intraprostatic local radiorecurrence (LRR) after definitive radiation is being increasingly identified due to the implementation of molecular positron emission tomography (PET)/computed tomography (CT) imaging for the evaluation of biochemical recurrence. Salvage high-dose rate (HDR) brachytherapy offers a promising local therapy option, with encouraging toxicity and efficacy based on early series. Furthermore, the incorporation of advanced imaging allows for focal HDR to further reduce toxicity to maximise the therapeutic ratio. The objectives of the 'focal salvage HDR brachytherapy for locally recurrent prostate cancer in patients treated with prior radiotherapy' (F-SHARP) trial are to determine the acute and late toxicity and efficacy outcomes of focal salvage HDR brachytherapy for LRR prostate cancer. STUDY DESIGN: The F-SHARP is a multi-institutional two-stage Phase I/II clinical trial of salvage focal HDR brachytherapy for LRR prostate cancer enrolling patients at three centres. ENDPOINTS: The primary endpoint is the acute radiation-related Grade ≥3 Common Terminology Criteria for Adverse Events (CTCAE, version 4.03) genitourinary (GU) and gastrointestinal (GI) toxicity rate, defined as within 3 months of brachytherapy. Secondary endpoints include acute and late CTCAE toxicity, biochemical failure, patterns of clinical progression, disease-specific and overall survival, and health-related quality of life, as measured by the International Prostate Symptom Score and 26-item Expanded Prostate Cancer Index Composite instruments. PATIENTS AND METHODS: Key eligibility criteria include: biopsy confirmed LRR prostate adenocarcinoma after prior definitive radiation therapy using any radiotherapeutic modality, no evidence of regional or distant metastasis, and cT1-3a Nx or N0 prostate cancer at initial treatment. All patients will have multiparametric magnetic resonance imaging and molecular PET/CT imaging if possible. In Stage 1, seven patients will be accrued. If there are two or more GI or GU Grade ≥3 toxicities, the study will be stopped. Otherwise, 17 additional patients will be accrued (total of 24 patients). For Stage 2, the cohort will expand to 62 subjects to study the efficacy outcomes, long-term toxicity profile, quality of life, and compare single- vs multi-fraction HDR. Transcriptomic analysis of recurrence biopsies will be performed to identify potential prognostic and predictive biomarkers.

Dosimetric and workflow impact of synthetic-MRI use in prostate high-dose-rate brachytherapy.

PURPOSE: Target and organ delineation during prostate high-dose-rate (HDR) brachytherapy treatment planning can be improved by acquiring both a postimplant CT and MRI. However, this leads to a longer treatment delivery workflow and may introduce uncertainties due to anatomical motion between scans. We investigated the dosimetric and workflow impact of MRI synthesized from CT for prostate HDR brachytherapy. METHODS AND MATERIALS: Seventy-eight CT and T2-weighted MRI datasets from patients treated with prostate HDR brachytherapy at our institution were retrospectively collected to train and validate our deep-learning-based image-synthesis method. Synthetic MRI was assessed against real MRI using the dice similarity coefficient (DSC) between prostate contours drawn using both image sets. The DSC between the same observer's synthetic and real MRI prostate contours was compared with the DSC between two different observers' real MRI prostate contours. New treatment plans were generated targeting the synthetic MRI-defined prostate and compared with the clinically delivered plans using target coverage and dose to critical organs. RESULTS: Variability between the same observer's prostate contours from synthetic and real MRI was not significantly different from the variability between different observer's prostate contours on real MRI. Synthetic MRI-planned target coverage was not significantly different from that of the clinically delivered plans. There were no increases above organ institutional dose constraints in the synthetic MRI plans. CONCLUSIONS: We developed and validated a method for synthesizing MRI from CT for prostate HDR brachytherapy treatment planning. Synthetic MRI use may lead to a workflow advantage and removal of CT-to-MRI registration uncertainty without loss of information needed for target delineation and treatment planning.

Multi-institutional Development and Validation of Contouring Guidelines for Para-aortic Elective Nodal Irradiation in Prostate Cancer Based on Patterns of Involvement on Targeted Molecular Imaging Positron Emission Tomography/Computed Tomography.

PURPOSE: Molecular imaging better identifies anatomic regions of metastatic spread of prostate cancer compared with conventional imaging, resulting in para-aortic (PA) nodal metastases being increasingly identified. Consequently, some radiation oncologists electively treat the PA lymph node region in patients with gross or high risk of PA nodal involvement. The anatomic locations of at-risk PA lymph nodes for prostate cancer are unknown. Our objective was to use molecular imaging to develop guidelines for the optimal delineation of the PA clinical target volume (CTV) in patients with prostate cancer. METHODS AND MATERIALS: We conducted a multi-institutional retrospective cohort study of patients with prostate cancer undergoing 18F-fluciclovine or 18F-DCFPyL prostate-specific membrane antigen positron emission tomography (PET)/computed tomography (CT). Images of patients with PET-positive PA nodes were imported into the treatment planning system, avid nodes were contoured, and measurements were taken in relation to anatomic landmarks. A contouring guideline that encompassed the location of ≥95% of PET-positive PA nodes was created using descriptive statistics and then validated in an independent data set. RESULTS: Five hundred fifty-nine patients had molecular PET/CT imaging in the development data set (78% 18F-fluciclovine, 22% prostate-specific membrane antigen). Seventy-six patients (14%) had evidence of PA nodal metastasis. We determined that expanding the CTV to 1.8 cm left of the aorta, 1.4 cm right of the inferior vena cava (IVC), 7 mm posterior to the aorta/IVC or to the vertebral body, and superiorly to the T11/T12 vertebral interface, with the anterior border 4 mm anterior to the aorta/IVC and inferior border at the bifurcation of the aorta/IVC, resulted in coverage of ≥95% of PET-positive PA nodes. When the guideline was used in the independent validation data set (246 patients with molecular PET/CT imaging, of whom 31 had PA nodal metastasis), 97% of nodes were encompassed, thereby validating our guideline. CONCLUSIONS: We used molecular PET/CT imaging to determine the anatomic locations of PA metastases to develop contouring guidelines for creating a prostate cancer PA CTV. Although the optimal patient selection and clinical benefits of PA radiation therapy remain uncertain, our results will aid in delineating the optimal target when PA radiation therapy is pursued.

Dosimetric Evaluation of Organs at Risk From SAVE Protocol.

PURPOSE: The objective of this work was to evaluate dosimetric characteristics to organs at risk (OARs) from short-course adjuvant vaginal cuff brachytherapy (VCB) in early endometrial cancer compared with standard of care (SOC) in a multi-institutional prospective randomized trial. METHODS AND MATERIALS: SAVE (Short Course Adjuvant Vaginal Brachytherapy in Early Endometrial Cancer Compared to Standard of Care) is a prospective, phase 3, multisite randomized trial in which 108 patients requiring VCB were randomized to an experimental short-course arm (11 Gy × 2 fractions [fx] to surface) and SOC arm. Those randomized to the SOC arm were subdivided into treatment groups based on treating physician discretion as follows: 7 Gy × 3 fx to 5 mm, 5 to 5.5 Gy × 4 fx to 5 mm, and 6 Gy × 5 fx to surface. To evaluate doses to OARs of each SAVE cohort, the rectum, bladder, sigmoid, small bowel, and urethra were contoured on planning computed tomography, and doses to OARs were compared by treatment arm. Absolute doses for each OAR and from each fractionation scheme were converted to 2 Gy equivalent dose (EQD23). Each SOC arm was compared with the experimental arm separately using 1-way analysis of variance, followed by pairwise comparisons using Tukey's honestly significant difference test. RESULTS: The experimental arm had significantly lower doses for rectum, bladder, sigmoid, and urethra compared with the 7 Gy × 3 and 5 to 5.5 Gy × 4 fractionation schemes; however, the experimental arm did not differ from the 6 Gy × 5 fractionation scheme. For small bowel doses, none of the SOC fractionation schemes were statistically different than the experimental. The highest EQD23 doses to the examined OARs were observed to come from the most common dose fractionation scheme of 7 Gy × 3 fx. With a short median follow-up of 1 year, there have been no isolated vaginal recurrences. CONCLUSIONS: Experimental short-course VCB of 11 Gy × 2 fx to the surface provides a comparable biologically effective dose to SOC courses. Experimental short-course VCB was found to reduce or be comparable to D2cc and D0.1cc EQD23 doses to rectum, bladder, sigmoid, small bowel, and urethra critical structures. This may translate into a comparable or lower rate of acute and late adverse effects.

Effect of scattered megavoltage x-rays on markerless tumor tracking using dual energy kilovoltage imaging.

PURPOSE: To determine the effect of megavoltage (MV) scatter on the accuracy of markerless tumor tracking (MTT) for lung tumors using dual energy (DE) imaging and to consider a post-processing technique to mitigate the effects of MV scatter on DE-MTT. METHODS: A Varian TrueBeam linac was used to acquire a series of interleaved 60/120 kVp images of a motion phantom with simulated tumors (10 and 15 mm diameter). Two sets of consecutive high/low energy projections were acquired, with and without MV beam delivery. The MV field sizes (FS) ranged from 2 × 2 cm2 -6 × 6 cm2 in steps of 1 × 1 cm2 . Weighted logarithmic subtraction was performed on sequential images to produce soft-tissue images for kV only (DEkV ) and kV with MV beam on (DEkV+MV ). Wavelet and fast Fourier transformation filtering (wavelet-FFT) was used to remove stripe noise introduced by MV scatter in the DE images ( DE kV + MV Corr ${\rm{DE}}_{{\rm{kV}} + {\rm{MV}}}^{{\rm{Corr}}}$ ). A template-based matching algorithm was then used to track the target on DEkV, DEkV+MV , and DE kV + MV Corr ${\rm{DE}}_{{\rm{kV}} + {\rm{MV}}}^{{\rm{Corr}}}$ images. Tracking accuracy was evaluated using the tracking success rate (TSR) and mean absolute error (MAE). RESULTS: For the 10 and 15 mm targets, the TSR for DEkV images was 98.7% and 100%, and MAE was 0.53 and 0.42 mm, respectively. For the 10 mm target, the TSR, including the effects of MV scatter, ranged from 86.5% (2 × 2 cm2 ) to 69.4% (6 × 6 cm2 ), while the MAE ranged from 2.05 mm to 4.04 mm. The application of wavelet-FFT algorithm to remove stripe noise ( DE kV + MV Corr ${\rm{DE}}_{{\rm{kV}} + {\rm{MV}}}^{{\rm{Corr}}}$ ) resulted in TSR values of 96.9% (2 × 2 cm2 ) to 93.4% (6 × 6 cm2 ) and subsequent MAE values were 0.89 mm to 1.37 mm. Similar trends were observed for the 15 mm target. CONCLUSION: MV scatter significantly impacts the tracking accuracy of lung tumors using DE images. Wavelet-FFT filtering can improve the accuracy of DE-MTT during treatment.

Embracing a future of progress in gynecologic brachytherapy.

In the last 20 years, gynecologic brachytherapy has made tremendous advancements, most prominently evidenced by the evolution of cervical cancer brachytherapy. In its 20 year history, Brachytherapy has become known as a journal of science, education, and advocacy for our specialty and for our patients. In this review, we celebrate the 25 most impactful manuscripts in gynecologic brachytherapy in the journal's history.

Radiation Therapy for Endometrial Cancer: An American Society for Radiation Oncology Clinical Practice Guideline.

PURPOSE: With the results of several recently published clinical trials, this guideline informs on the use of adjuvant radiation therapy (RT) and systemic therapy in the treatment of endometrial cancer. Updated evidence-based recommendations provide indications for adjuvant RT and the associated techniques, the utilization and sequencing of adjuvant systemic therapies, and the effect of surgical staging techniques and molecular tumor profiling. METHODS: The American Society for Radiation Oncology convened a multidisciplinary task force to address 6 key questions that focused on the adjuvant management of patients with endometrial cancer. The key questions emphasized the (1) indications for adjuvant RT, (2) RT techniques, target volumes, dose fractionation, and treatment planning aims, (3) indications for systemic therapy, (4) sequencing of systemic therapy with RT, (5) effect of lymph node assessment on utilization of adjuvant therapy, and (6) effect of molecular tumor profiling on utilization of adjuvant therapy. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for quality of evidence grading and strength of recommendation. RESULTS: The task force recommends RT (either vaginal brachytherapy or external beam RT) be given based on the patient's clinical-pathologic risk factors to reduce risk of vaginal and/or pelvic recurrence. When external beam RT is delivered, intensity modulated RT with daily image guided RT is recommended to reduce acute and late toxicity. Chemotherapy is recommended for patients with International Federation of Gynecology and Obstetrics (FIGO) stage I to II with high-risk histologies and those with FIGO stage III to IVA with any histology. When sequencing chemotherapy and RT, there is no prospective data to support an optimal sequence. Sentinel lymph node mapping is recommended over pelvic lymphadenectomy for surgical nodal staging. Data on sentinel lymph node pathologic ultrastaging status supports that patients with isolated tumor cells be treated as node negative and adjuvant therapy based on uterine risk factors and patients with micrometastases be treated as node positive. The available data on molecular characterization of endometrial cancer are compelling and should be increasingly considered when making recommendations for adjuvant therapy. CONCLUSIONS: These recommendations guide evidence-based best clinical practices on the use of adjuvant therapy for endometrial cancer.

Effect of different noise reduction techniques and template matching parameters on markerless tumor tracking using dual-energy imaging.

PURPOSE: To evaluate the impact of various noise reduction algorithms and template matching parameters on the accuracy of markerless tumor tracking (MTT) using dual-energy (DE) imaging. METHODS: A Varian TrueBeam linear accelerator was used to acquire a series of alternating 60 and 120 kVp images (over a 180° arc) using fast kV switching, on five early-stage lung cancer patients. Subsequently, DE logarithmic weighted subtraction was performed offline on sequential images to remove bone. Various noise reduction techniques-simple smoothing, anticorrelated noise reduction (ACNR), noise clipping (NC), and NC-ACNR-were applied to the resultant DE images. Separately, tumor templates were generated from the individual planning CT scans, and band-pass parameter settings for template matching were varied. Template tracking was performed for each combination of noise reduction techniques and templates (based on band-pass filter settings). The tracking success rate (TSR), root mean square error (RMSE), and missing frames (percent unable to track) were evaluated against the estimated ground truth, which was obtained using Bayesian inference. RESULTS: DE-ACNR, combined with template band-pass filter settings of σlow  = 0.4 mm and σhigh  = 1.6 mm resulted in the highest TSR (87.5%), RMSE (1.40 mm), and a reasonable amount of missing frames (3.1%). In comparison to unprocessed DE images, with optimized band-pass filter settings of σlow  = 0.6 mm and σhigh  = 1.2 mm, the TSR, RMSE, and missing frames were 85.3%, 1.62 mm, and 2.7%, respectively. Optimized band-pass filter settings resulted in improved TSR values and a lower missing frame rate for both unprocessed DE and DE-ACNR as compared to the use previously published band-pass parameters based on single energy kV images. CONCLUSION: Noise reduction strategies combined with the optimal selection of band-pass filter parameters can improve the accuracy and TSR of MTT for lung tumors when using DE imaging.

Lymphocyte sparing normal tissue effects in the clinic (LymphoTEC): A systematic review of dose constraint considerations to mitigate radiation-related lymphopenia in the era of immunotherapy.

BACKGROUND: Radiation-related lymphopenia has been associated with suboptimal tumor control rates leading to inferior survival outcomes. To date, no standardized dose constraints are available to limit radiation dose to resident and circulating lymphocyte populations. We undertook this systemic review of the literature to provide a synopsis of the dosimetric predictors of radiation-related lymphopenia in solid malignancies. METHODOLOGY: A systematic literature review of PubMed (National Institutes of Health), Cochrane Central (Cochrane collaboration), and Google Scholar was conducted with the following keywords: "radiation", "lymphopenia", "cancer", "dosimetric predictors" with an inclusion deadline of May 31, 2022. Studies that met prespecified inclusion criteria were designated either Good, Fair, or Poor Quality based on the Newcastle-Ottawa quality assessment. The dosimetric parameters derived from Good Quality studies were tabulated as LymphoTEC dose constraints. Dosimetric parameters derived from Fair and Poor-quality studies were grouped as optional. RESULTS: An initial systematic search of the literature yielded 1,632 articles. After screening, a total of 48 studies met inclusion criteria and were divided into the following categories: central nervous system (CNS, 6), thoracic (11), gastrointestinal (26), gynecologic (2), head and neck, breast, and genitourinary (one each) cancers. Lung mean dose, heart mean dose, brain V25, spleen mean dose, estimated dose to immune cells, and bone marrow V10 were among the strongest predictors for severe lymphopenia related to radiotherapy. CONCLUSION: Optimizing the delivery of radiation therapy to limit dose to lymphocyte-rich structures may curb the negative oncologic impact of lymphocyte depletion. The dose constraints described herein may be considered for prospective validation and future use in clinical trials to limit risk of radiation-related lymphopenia and possibly improve cancer-associated outcomes.

Health-Related Quality of Life and Toxicity After Definitive High-Dose-Rate Brachytherapy Among Veterans With Prostate Cancer.

PURPOSE: High-dose-rate (HDR) brachytherapy (BT) is a well-tolerated and effective treatment for prostate cancer. There is limited research, however, investigating toxicity outcomes with HDRBT treatment among veterans. The objective of this study is to assess the impact on health-related quality of life (hrQOL) and physician-graded toxicities associated with HDRBT as monotherapy among veterans treated at Edward Hines, Jr. Veterans Affairs Hospital in Hines, Illinois. METHODS: Between 2016 and 2019, 74 veterans with low- or intermediate-risk prostate cancer were treated with HDRBT as monotherapy with 27 Gy in 2 fractions, delivered over 2 implants. Veteran-reported hrQOL in the genitourinary (GU), gastrointestinal (GI), and sexual domains was assessed using the International Prostate Symptoms Score (IPSS) and Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire. Mixed linear effect models were used to assess differences in the hrQOL scores at follow-up compared with baseline scores. Statistically significant differences in hrQOL scores from baseline were further assessed for clinical significance, using minimal clinically important difference (MCID) evaluations. RESULTS: Median follow-up was 18 months. Veterans reported declines in GU, GI, and sexual hrQOL scores immediately after treatment, with the IPSS and EPIC-26 hrQOL scores all displaying significant decrease from baseline over time. The majority of the declines in hrQOL scores met criteria for MCID. These hrQOL scores trended toward a return to baseline, with the EPIC-26 urinary obstruction score returning to baseline at the 18-month follow-up assessment and the EPIC-26 bowel score returning to baseline at the 12-month follow-up. The IPSS, urinary incontinence, and sexual scores did not return to baseline at 18 months. The grade 2 maximum physician-graded GU, GI, and sexual toxicity rates were 65%, 5%, and 53%, respectively. There was 1 incidence of grade 3 GU toxicity but no grade 3 GI or sexual toxicity. CONCLUSIONS: HDRBT as monotherapy is a well-tolerated treatment option for veterans with low- or intermediate-risk prostate cancer, with favorable veteran-reported and physician-graded toxicities. Veterans should be educated about HDRBT as an option when counseled regarding treatment for localized prostate cancer.

ACR-ABS-ASTRO practice parameter for the performance of radionuclide-based high-dose-rate brachytherapy.

PURPOSE: This practice parameter aims to detail the processes, qualifications of personnel, patient selection, equipment, patient and personnel safety, documentation, and quality control and improvement necessary for an HDR brachytherapy program. METHODS AND MATERIALS: This practice parameter was revised collaboratively by the American College of Radiology (ACR), the American Brachytherapy Society (ABS), and the American Society for Radiation Oncology (ASTRO). RESULTS: Brachytherapy is a radiotherapeutic modality in which radionuclide or electronic sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary, intraluminal, or interstitial application. Brachytherapy alone or combined with external beam radiotherapy plays an important role in the management and treatment of patients with cancer. High-dose-rate (HDR) brachytherapy uses radionuclides, such as iridium-192, at dose rates of ≥12 Gy/hr to a designated target point or volume, and it is an important treatment for a variety of malignant and benign conditions. Its use allows for application of high doses of radiation to defined target volumes with relative sparing of adjacent critical structures. CONCLUSIONS: HDR brachytherapy requires detailed attention to personnel, equipment, patient and personnel safety, and continuing staff education. Coordination between the radiation oncologist and treatment planning staff and effective quality assurance procedures are important components of successful HDR brachytherapy programs.

Radiation Toxicity in Patients With Collagen Vascular Disease: A Meta-Analysis of Case-Control Studies.

PURPOSE: Several retrospective series have reported that patients with collagen vascular disease (CVD) are at increased risk of radiation (RT) toxicity. However, the evidence is mixed, and many series lack control groups. We performed a meta-analysis including only case-cohort or randomized studies that examined the risk of RT toxicity for patients with CVD compared with controls. METHODS AND MATERIALS: Meta-analysis of Observational Studies in Epidemiology guidelines were used to perform a comprehensive search identifying case-control or randomized studies reporting RT toxicity outcomes for patients with CVD versus controls. Data were synthesized from studies reporting grade 2 to 3 or more (G2/3 +) acute and late RT toxicities. Results were analyzed with fixed effects meta-analysis on the random-effects model for between-study heterogeneity; otherwise, the fixed-effects model was used. Hazard ratio or odds ratio (OR) were the effect-size estimators, as appropriate. RESULTS: Ten studies were included, with 4028 patients (CVD: 406, control: 3622). Patients with CVD had higher rates of acute G2/3 + toxicity (26.2% vs 16.5%, OR [odds ratio] 2.01; P < .001) and late G2/3 + toxicity (18.4% vs 10.1%, OR 2.37; P < .001). Higher rates of late G2/3 + toxicity were observed for CVD patients with systemic lupus erythematous (21% vs 9.7%; OR 2.55, P = .03), systemic scleroderma (31.8% vs 9.7%, OR 3.85; P = .03), rheumatoid arthritis (11.7% vs 8.4%, OR = 2.56; P = .008), and those irradiated to the pelvis/abdomen (32.2% vs 11.9%, OR 3.29; P = .001), breast (14.7% vs 4.4%, OR 3.51; P = .003), thorax (12.5% vs 8.7%, OR 3.46; P < .001), and skin (14.6% vs 5.2%, OR 2.59; P = .02). Late grade 5 toxicities were significantly higher for patients with CVD, although absolute rates were low (3.9% vs 0.6%, OR = 7.81; P = .01). CONCLUSIONS: Moderate and severe toxicities are more likely in patients with CVD, with variable risk depending on toxicity grade, CVD subtype, treatment site, and dose. Severe toxicities are uncommon. These factors should be considered when informing patients of treatment-related risks and monitoring for morbid treatment sequelae.

Validating Modern NRG Oncology Pelvic Nodal and Groupe Francophone de Radiothérapie Urologique Prostate Bed Contouring Guidelines for Post-Prostatectomy Salvage Radiation: A Secondary Analysis of the LOCATE Trial.

PURPOSE: We used the patterns of recurrence on 18F-fluciclovine positron emission tomography (PET)-computed tomography (CT) in patients enrolled in the LOCATE trial after prostatectomy to evaluate how well the most recent NRG Oncology and Groupe Francophone de Radiothérapie Urologique (GFRU) contouring recommendations encompassed all sites of recurrence in the prostate fossa and pelvic nodes in comparison to former Radiation Therapy Oncology Group (RTOG) recommendations. METHODS AND MATERIALS: Patients with biochemically recurrent prostate cancer after radical prostatectomy with a positive finding within the prostate fossa or pelvic nodes on 18F-fluciclovine PET/CTs were identified from the LOCATE patient population. Areas of gross disease were delineated. Prostate fossa contours were delineated using both the 2010 RTOG consensus guidelines and the recently published 2020 GFRU consensus guidelines. Pelvic nodes were contoured with both the 2009 RTOG consensus guidelines and the 2020 NRG consensus guidelines. The performance of the contouring guidelines was assessed by determining what proportion of gross recurrent lesions were encompassed completely or marginally. RESULTS: Of the 213 patients within the LOCATE trial, 45 patients were eligible for analysis with positive 18F-fluciclovine PET findings. Of the 30 total prostate fossa recurrences, the 2010 RTOG contour covered 20 (67%) and missed or marginally covered 10 (33%). The 2020 GFRU contour covered 27 recurrences (90%), and missed or marginally covered 3 (10%). Of the 43 total nodal recurrences, the 2009 RTOG pelvic nodal contour covered 29 nodes (67%), and missed or marginally covered 14 (32%). The 2020 NRG pelvic nodal contour covered 43 nodes (100%), with no misses or marginal coverage. CONCLUSIONS: This secondary analysis of the LOCATE trial exemplifies the improved coverage of the latest prostate fossa contouring recommendations from the GFRU. Similarly, it also validates the updated 2020 NRG pelvic nodal contouring guidelines by demonstrating improved coverage of recurrent disease in this patient population.

Uterine perforation during brachytherapy for cervical cancer: Complications, outcomes, and best practices for forward treatment planning and management.

PURPOSE: The purpose of the study was to determine the incidence of uterine perforations, review the associated complications, and propose guidelines for management of perforations after brachytherapy. METHODS AND MATERIALS: A retrospective chart review was conducted for all patients with cervical cancer who received single or multiple high-dose-rate brachytherapy implants between April 2006 and May 2017 at a single academic institution. CT and MRI images were retrospectively evaluated to record incidences of uterine perforation of tandem during brachytherapy. Acute and long-term complications during and after treatment were scored using the Common Terminology Criteria for Adverse Events, Version 4.0, of the National Cancer Institute. RESULTS: A total of 123 patients were included in the study. Perforations were observed in 22 patients (17.9%) with 31 (6.4%) of the 482 total implants. Of the different categories of adverse events, only the rate of acute infectious complications among those with perforations (n = 3, 13.6%) versus those without perforations (n = 3, 3.0%) was significant (p = 0.040). Two of the three perforated patients with acute infections had mild urinary tract infections, and all resolved without complications or treatment delays. The remaining one patient had a frank perforation of the anterior uterine wall with a subsequent Grade 3 pyometra infection despite administration of prophylactic antibiotics and 1-week treatment delay. This case was eventually resolved with cervical dilation and evacuation of fluid. Long-term complications were not different between the two arms. CONCLUSIONS: Patients with cervical cancer with uterine perforations may be able to safely proceed with brachytherapy treatment without delay or need for prophylactic antibiotics in the acute setting. Further validating data would be able to assist in establishing a new standard of care and help prevent unnecessary and harmful breaks during treatment.

Computed tomography versus magnetic resonance imaging in high-dose-rate prostate brachytherapy planning: The impact on patient-reported health-related quality of life.

PURPOSE: High-dose-rate (HDR) prostate brachytherapy uses volumetric imaging for treatment planning. Our institution transitioned from computed tomography (CT)-based planning to MRI-based planning with the hypothesis that improved visualization could reduce treatment-related toxicity. This study aimed to compare the patient-reported health-related quality of life (hrQOL) and physician-graded toxicity outcomes of CT-based and MRI-based HDR prostate brachytherapy. METHODS: From 2016 to 2019, 122 patients with low- or intermediate-risk prostate cancer were treated with HDR brachytherapy as monotherapy. Patients underwent CT only or CT and MRI imaging for treatment planning and were grouped per treatment planning imaging modality. Patient-reported hrQOL in the genitourinary (GU), gastrointestinal (GI), and sexual domains was assessed using International Prostate Symptom Score and Expanded Prostate Cancer Index Composite Short Form-26 questionnaires. Baseline characteristics, changes in hrQOL scores, and physician-graded toxicities were compared between groups. RESULTS: The median follow-up was 18 months. Patient-reported GU, GI, and sexual scores worsened after treatment but returned toward baseline over time. The CT cohort had a lower baseline mean International Prostate Symptom Score (5.8 vs. 7.8, p = 0.03). The other patient-reported GU and GI scores did not differ between groups. Overall, sexual scores were similar between the CT and MRI cohorts (p = 0.08) but favored the MRI cohort at later follow-up with a smaller decrease in Expanded Prostate Cancer Index Composite Short Form-26 sexual score from baseline at 18 months (4.9 vs. 19.8, p = 0.05). Maximum physician-graded GU, GI, and sexual toxicity rates of grade ≥2 were 68%, 3%, and 53%, respectively, with no difference between the cohorts (p = 0.31). CONCLUSION: Our study shows that CT- and MRI-based HDR brachytherapy results in similar rates of GU and GI toxicity. MRI-based planning may result in improved erectile function recovery compared with CT-based planning.