Modulated Radiation Therapy Treatment Research Articles

Impact of Facility Treatment Volume on Stereotactic Ablative Radiotherapy (SABR) Outcomes in Early-Stage Non-Small Cell Lung Cancer (NSCLC)

Prior research suggests that radiation oncologist provider experience may influence outcomes for radiation treatment modalities requiring greater technical expertise for given disease sites. We investigated whether institution treatment volume (TV) for SABR technique impacted survival outcomes for patients with NSCLC.We conducted a retrospective cohort study using the Veteran's Affairs Informatics and Computing Infrastructure (VINCI) database to identify patients who underwent treatment for NSCLC between 2012 and 2017 at Veteran's Health Administration Medical Centers (VHAMCs). Patients were included in the cohort if they had tumor (T) stage 1 or 2 disease, node negative (N0) disease, and underwent SABR radiation treatment based on associated Current Procedural Terminology codes. We conducted univariate and multivariate analyses for overall survival (OS) and cause-specific survival (CSS) using Cox regression models accounting for age, sex, race, histology, T stage, tobacco history, ECOG status, and VHAMC facility TV. TV was calculated as the total number of SABR treatments performed per facility over the study period and was categorized into high and low volume groups based on a median TV cutoff.The observational cohort included N = 433 patients with early-stage NSCLC who underwent treatment with SABR across 25 VHAMC facilities. Most patients (83.1%) had T stage 1 disease, and nearly equal proportions had SCC (31.2%) and adenocarcinoma (32.5%) histologies, with the remaining having clinical diagnoses of NSCLC. Median facility TV was 29 SABR treatments (interquartile range 19-33). Median follow up was 657 days. Estimated 2-year overall and cause-specific survival rates were 78.4% (95% CI: 73.9% - 82.1%) and 87.0% (95% CI: 83.2% - 90.0%), respectively. On univariate analysis, high versus low facility TV was not significantly associated with OS (hazard ratio (HR) 1.08, 95% CI: 0.74-1.58) or CSS (HR 1.06, 95% CI: 0.65 - 1.73). Similarly, facility volume was not associated with OS or CSS on multivariate analysis. In a sensitivity analysis, facility volume was not associated with survival outcomes when treated as a continuous variable. Covariates associated with decreased OS included male sex (HR 4.5, P < 0.05), age over 65 (HR 1.77, P < 0.05), ECOG status 2 or greater (HR 1.94, P < 0.05), SCC histology (HR 1.66, P < 0.05), and T stage 2 disease (HR 1.68, P < 0.05).In this observational cohort of patients treated at VHAMCs, facility TV was not associated with survival outcomes for early-stage NSCLC radiation treatment using SABR technique. Research is ongoing to account for factors including baseline pulmonary function, comorbidities, and variations in institutional treatment patterns such as propensity for treatment with surgery versus radiation.

Evaluation of the impact of parameters on the gamma index for breast cancer treatments

Volumetric modulated arc radiotherapy treatments (VMAT) can achieve highly conformed dose distributions, however, due to the complexity of the technique, there may have differences between the planned and administered dose distributions, generated by the precision in the dose calculation of the treatment planning system (TPS) or by the errors associated with it. One way to quantify the difference between both dose distributions is by using the gamma index; however, there is no accord regarding the parameters that should be used in its analysis. On the other hand, this gamma index may depend on the pathology and the area to be treated. For this reason, the present work aims to evaluate different parameters of the analysis of the gamma index for breast cancer treatments, these are local and global normalization, the analysis criteria (1%/1 mm, 2%/2 mm, 3%/2 mm, 2%/3 mm, 3%/3 mm and 5%/3 mm) and the low dose threshold (LDT) of 5% and 10%. For this, 30 treatment plans performed with VMAT technique in a 6 MV Infinity linear accelerator (Elekta, Stockholm, Sweden) were analyzed, calculated with the TPS Monaco V.5.11.03 (Elekta, Stockholm, Sweden) and measured with the Octavius 4D system (PTW, Freiburg, Germany). The results of the analysis of the global gamma index were of a gamma passing rate (%GP) greater than 95% for analysis criteria of 3%/3 mm and 5%/3 mm, however, for these same parameters in the local gamma index analysis the results are 85.8% and 91.1% respectively. In addition, from the LDT evaluation, it is observed that there is a mean increase of %GP for the local gamma index analysis and a mean decrease of %GP for the global gamma index analysis, for the LDT from 5% to 10%. On the other hand, the standard deviation is lower in the global gamma index analysis than in the local one, and it decreases when the analysis criteria are less strict. It is concluded that there is not a great difference in choosing the LDT of 5% or 10%. When the gamma analysis criteria are less strict, the %GP increases both for the analysis of the local and global gamma index, taking this into account, each parameter should be used carefully according to the treatment plan to be analyzed, taking into account the advantages and disadvantages of each parameter.

Quality assurance of dysphagia-optimised intensity modulated radiotherapy treatment planning for head and neck cancer.

This study aimed to assess the impact of the margin applied to the clinical target volume, to create the planning target volume, on plan quality of a novel dysphagia-optimised intensity modulated radiotherapy technique developed within a head and neck cancer multicentre randomised controlled trial. Protocol compliant plans were used for a single benchmark planning case. Larger margins were associated with higher doses to adjacent organs at risk, particularly the inferior pharyngeal constrictor muscle, but coincided with some improved low dose target coverage. A 3mm margin is recommended for this technique if local practices allow.

Incorporating Clinical Imaging into the Delivery of Microbeam Radiation Therapy

Synchrotron microbeam radiation therapy is a promising pre-clinical radiation treatment modality; however, it comes with many technical challenges. This study describes the image guidance protocol used for Australia’s first long-term pre-clinical MRT treatment of rats bearing 9L gliosarcoma tumours. The protocol utilises existing infrastructure available at the Australian Synchrotron and the adjoining Monash Biomedical Imaging facility. The protocol is designed and optimised to treat small animals utilising high-resolution clinical CT for patient specific tumour identification, coupled with conventional radiography, using the recently developed SyncMRT program for image guidance. Dosimetry performed in small animal phantoms shows patient dose is comparable to standard clinical doses, with a CT associated dose of less than 1.39cGy and a planar radiograh dose of less than 0.03cGy. Experimental validation of alignment accuracy with radiographic film demonstrates end to end accuracy of less than ±0.34mm in anatomical phantoms. Histological analysis of tumour-bearing rats treated with microbeam radiation therapy verifies that tumours are targeted well within applied treatment margins. To date, this technique has been used to treat 35 tumour-bearing rats.

26016 Combined modality therapies adjunctive to hedgehog inhibitors in the management of basal cell carcinoma: A systematic review and pooled-analysis

Importance: Surgical and radiation treatment modalities can have limited effectiveness in the management of patients with locally advanced basal cell carcinoma (laBCC) due to size, location, aggressive lesion morphologies and higher potential for metastasis. Hedgehog inhibitors show promise but have limitations due to low rates of complete response, undesirable adverse effects with longer treatment regimens and tumor recurrence after discontinuation.

Cost-Utility Analysis of Radiation Treatment Modalities for Intermediate-Risk Prostate Cancer.

Introduction: Variable costs of different radiation treatment modalities have played an important factor in selecting the most appropriate treatment for patients with intermediate-risk prostate cancer. Methods: Analysis using a Markov model was conducted to simulate 20-year disease trajectory, quality-adjusted life years (QALYs) and health system costs of a cohort of intermediate-risk prostate cancer patients with mean age of 60 years. Clinical outcomes on toxicity and disease recurrence were measured and a probabilistic sensitivity analysis was performed, varying input parameters simultaneously according to their distributions. Results: Among the six radiation treatment modalities, including conventionally fractionated intensity-modulated radiation therapy (IMRT), hypofractionated IMRT, IMRT combined with high-dose-rate (HDR) brachytherapy, HDR brachytherapy monotherapy, low-dose-rate brachytherapy monotherapy, and stereotactic body radiotherapy (SBRT), SBRT was found to be more cost-effective when compared with LDR-b and other treatment modalities, resulting in an incremental cost–utility ratio of $2985 per QALY. Conclusions: Stereotactic body radiotherapy is the most cost-effective radiation treatment modality in treatment of intermediate-risk prostate cancer, while treatment toxicity and cost data are the key drivers of the cost–utility. Further work is required with long-term follow-up for SBRT.

First Experience of Intra-Operative Radiation Therapy (IORT) during Kyphoplasty in Patients Diagnosed with Spinal Metastasis in Iran

Object: Based on previous studies, 30 to 40% of cancer patients are diagnosed with bone metastasis. Median Overall Survival (OS) of patients who are diagnosed with spinal metastasis (vertebral structures) is about 7 to 9 months which with recent progresses in oncologic and radiotherapy treatment modalities, their prognosis is slightly developed. In this study, authors plan to evaluate the effects of Intra-operative Radiation Therapy (IORT) in patients who are candidate for Kyphoplasty procedure. Methods: In this study, we have included patients who are diagnosed with spinal metastasis with radiological and histopathological confirmation. From July 2017 to December 2018, we have included 9 patients who fulfilled our predefined inclusion and exclusion criteria into our case-series study performed on Shohada Tajrish Hospital. Patients underwent radiotherapy during Kyphoplasty by our IORT device INTRABEAM (Carl Zeiss AG, Germany) as “Kypho-IORT’ procedure. We have evaluated these patients in post-operative period, as well as on 2 weeks, 1 month, 2 months and 6 months on post-operative period as our follow-up plan. Results: In this study, 9 patients (5 males and 4 females) with mean age of 68 years with spinal metastasis from breast (4 cases), prostate (2 cases), lung (2 cases) and gastrointestinal tract (1 case), underwent Kypho-IORT for 15 vertebrae levels with individualized radiation dose and interval. In postoperative follow-up period, patients exhibit pain relief (in 78%) assessed by Visual Assessment Score (VAS) and improvement in their Quality of Life (QoL). No major complications including new neurological deficit, major cement leak and embolic disorders were encountered during the study; however, minor cement leak encountered in 4 cases, and 2 patients have expired during follow up period; however, other patients are still alive and under follow-up with mean OS of 10 months. Conclusion: This study is the first experience of evaluation of IORT effects during Kyphoplasty in Iran, in patients diagnosed with spinal metastasis with poor prognosis, to improve their quality of life, local control rate and their OS. This study could be considered as one of the pioneers in continuing the evaluation of Kypho-IORT as a novel technique in these group of patients.

In Vitro Survival of Breast Cancer Cell Lines Following Chemotherapy or Radiotherapy in Comparison with Gold-mediated Phototherapy: Thesis Abstract

Thesis Abstract Background: Breast cancer is a heterogeneous disease that mandate efficient therapeutics, lower drug toxicity, and overcoming drug resistance. Combination therapy was suggested as a future treatment to attain the required efficacy and tolerable side effects. Aim: The current study aimed to compare and evaluate the efficacy of single and combined treatments in the MCF-7 breast cancer cell line. Materials and Methods: The study included seven MCF-7 groups according to the treatment modality. Cell viability was evaluated by MTT assay at different doses and time course treatments. Results: When nanoparticles were used alone, the starting point of significant cell death was 100 µg, but when using a photothermal combination modality the loss of viability % was bout 2- fold higher than nanoparticles alone especially in low concentrations and there was a significant difference between the 2 groups. There was a significant difference in cell viability between FAC + AuNPs group when compared to FAC only or control group (p ≤ 0.05). There was a significant difference in cell viability between Taxol + AuNPs when compared to control (p ≤ 0.05). there is a significant effect of radiation doses on cell viability within all subgroups ( p < 0.001 for R0, and p=0.001 for R2 subgroup). there is a significant effect of the radiation doses on the cell viability within each subgroup as indicated by significant p values ( p= 0.027 for RN0, and p=0.001 for RN2). Conclusion: Combined GNPs and FAC, paclitaxel, and Radiotherapy treatment modalities could improve breast cancer outcomes and prognosis.

The Management of Brain Metastases-Systematic Review of Neurosurgical Aspects.

Simple SummaryIn this comprehensive review, we focused on the neurosurgical treatment as an integrative part of the challenging multidisciplinary management of cerebral metastases, a neuro-oncologic entity, which has been observed to have an increased incidence over the last years. In selected cases, the surgical removal of the space-occupying mass reduces the intracranial pressure, normalizes the metabolic environment, reduces the symptom burden, and allows for the intensification of local and systemic adjuvant treatment. In detail, we discuss the incidence of brain metastases, the role of surgical resection, as well as the evolution of current neurosurgical techniques, the surgical morbidity and mortality of single and multiple lesions, and we enlighten the role of surgery for recurrent tumors.The multidisciplinary management of patients with brain metastases (BM) consists of surgical resection, different radiation treatment modalities, cytotoxic chemotherapy, and targeted molecular treatment. This review presents the current state of neurosurgical technology applied to achieve maximal resection with minimal morbidity as a treatment paradigm in patients with BM. In addition, we discuss the contribution of neurosurgical resection on functional outcome, advanced systemic treatment strategies, and enhanced understanding of the tumor biology.

Clinical practice guidelines for the management of adult diffuse gliomas.

To follow the revision of the fourth edition of WHO classification and the recent progress on the management of diffuse gliomas, the joint guideline committee of Chinese Glioma Cooperative Group (CGCG), Society for Neuro-Oncology of China (SNO-China) and Chinese Brain Cancer Association (CBCA) updated the clinical practice guideline. It provides recommendations for diagnostic and management decisions, and for limiting unnecessary treatments and cost. The recommendations focus on molecular and pathological diagnostics, and the main treatment modalities of surgery, radiotherapy, and chemotherapy. In this guideline, we also integrated the results of some clinical trials of immune therapies and target therapies, which we think are ongoing future directions. The guideline should serve as an application for all professionals involved in the management of patients with adult diffuse glioma and also a source of knowledge for insurance companies and other institutions involved in the cost regulation of cancer care in China and other countries.

Risk and Prognosis of Secondary Rectal Cancer After Radiation Therapy for Pelvic Cancer.

BackgroundThe relationship between pelvic radiation therapy (RT) and second primary rectal cancer (SPRC) is unclear. The aim of this study was to assess the risk and prognosis of SPRC after pelvic RT.Materials and MethodsData for patients who had primary pelvic cancer (PPC) between 1973 and 2016 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Multiple primary standardized incidence ratios (SIRs) were used to assess the risk of SPRC. Five-year overall survival (OS) and rectal cancer-specific survival (RCSS) were calculated using Kaplan–Meier curves.ResultsA total of 573,306 PPC patients were included, 141,225 of whom had been treated with RT. Primary cancers were located in the prostate (50.83%), bladder (24.18%), corpus uterus (16.26%), cervix (5.83%), and ovary (2.91%). A total of 1,491 patients developed SPRC. Overall, the patients who received RT were at increased risk of developing SPRC (SIR = 1.39, 95% confidence interval [CI]: 1.27–1.52). The risk of SPRC decreased in patients who did not undergo RT (SIR = 0.85, 95% CI: 0.80–0.91). The SIR for SPRC in patients who underwent external beam radiation therapy (EBRT) was 1.22 (95% CI: 1.09–1.36). The SIR for SPRC in patients who underwent a combination of EBRT and brachytherapy (EBRT–BRT) was 1.85 (95% CI: 1.60–2.14). For patients who received RT, the SIR for SPRC increased with time after a 5-year latency period from PPC diagnosis. The survival of RT-treated SPRC patients was significantly worse than that of patients with primary rectal cancer only (PRCO).ConclusionsPatients receiving pelvic RT were at an increased risk of developing SPRC. Different pelvic RT treatment modalities had different effects on the risk of SPRC. We suggest that long-term surveillance of SPRC risk is required for patients who have undergone pelvic RT, especially young patients.

Comparing Physician-reported Toxicity in Men with Localized Prostate Cancer Undergoing External Beam, Brachytherapy, or Combination Radiation Therapy

The purpose of this study is to compare physician-reported gastrointestinal (GI), genitourinary (GU) and sexual toxicity outcomes of men with localized prostate cancer undergoing dose-escalated external beam radiation therapy (EBRT), high-dose-rate (HDR) brachytherapy or low-dose-rate (LDR) brachytherapy monotherapy (HDRm or LDRm), EBRT with HDR BT boost (HDRb), and EBRT with LDR BT boost (LDRb). We performed a retrospective cohort study of a prospectively collected database of patients with localized prostate adenocarcinoma treated with EBRT, HDRm, LDRm, HDRb, or LDRb between 2004-2019 at our institution. Hormone therapy was delivered per physician discretion. Physician-reported GI, GU, and sexual toxicity were assessed using Common Terminology Criteria for Adverse Events (CTCAE) v5.0 at time points of 3 months, 6 months, 12 months, 18 months, and 24+ months. Stratified Fisher exact tests and generalized linear mixed effects models were used to assess for differences in the physician-graded toxicity rate between radiation treatment modalities. 555 men with prostate cancer met selection criteria. 277 (49.9%) received EBRT, 76 (13.7%) received LDRm, 30 (5.4%) received LDRb, 130 (23.4%) received HDRm, and 42 (7.6%) received HDRb. Median follow-up was 33 months (interquartile range [IQR]: 15-59). 130 (23%) had low risk, 280 (50%) had intermediate risk, and 145 (26%) had high risk disease. After 24 months, Grade 3+ GI toxicity with LDRb (15%) was higher than those in the EBRT group (1.2%), and it was higher than those in the HDRb cohort (0%; p = 0.01). No other pairwise comparisons were significant. The risk of Grade 2+ GU toxicity was higher with LDRm over HDRm at months 3, 21, and 24 (p = 0.03; p = 0.02; p = 0.03). HDRm patients had higher incidence of Grade 2+ sexual toxicity than EBRT patients in the first 3 months (p = 0.02). Compared to patients receiving EBRT, patients receiving HDRb, HDRm, or LDRm had higher sexual toxicity by month 15 (p = 0.002; p < 0.001; p = 0.004). By month 21, patients receiving HDRm remained more likely than those receiving EBRT to have sexual toxicity (p = 0.01). There were no significant differences in the sexual toxicity rates between groups after 24 months. In men treated with radiation therapy for localized prostate cancer, there are differences in physician-reported toxicity across radiation treatment modalities. Our study suggests lower rates of chronic GI toxicity in patients treated with HDRb as compared to LDRb and EBRT, lower rates of acute and chronic GU toxicities in patients treated with HDRm as compared to LDRm, and similar long-term sexual toxicity among the groups. The differences in the physician-graded toxicity profiles between radiation treatment modalities can be used in shared decision-making when selecting the best radiation therapy option for each patient.

External Validation of Early Quality of Life (QOL) Declines Correlated with Late QOL after Intensity Modulated, Low Dose Rate Brachytherapy, or Stereotactic Radiation for Prostate Cancer within a Prospective Trial

There is data on early toxicity associated with late toxicity, but there is currently a lack of data on quality of life (QOL) outcomes and evaluation for possible surrogacy between early and late toxicity. This is an evaluation of early QOL for prostate cancer across RT options with a validation within QOL from a SBRT prospective trial. An initial cohort of 898 patients (PROSTQA study and 3 institutions with prospective QOL data were pooled for analysis for IMRT (n = 162), LDR brachytherapy (n = 271), or SBRT (Robotic n = 392 and Linac n = 72) to the prostate with or without seminal vesicles) were evaluated for patient reported outcomes. Expanded Prostate Cancer Index (EPIC) QOL data for urinary, bowel, vitality, and sexual function was evaluated by pre-specified relevant thresholds for meaningful clinical differences (MCD) compared to baseline. Patients were evaluated for QOL at 1-2 month from the start of radiotherapy and at 24 months from the start of radiotherapy. Multivariate analysis (MVA) used general linear models to assess the correlation between QOL changes. This was then externally validated with QOL analysis from a prospective trial of robotic SBRT to the prostate alone to 38 Gy in 4 fractions of 259 patients assessing QOL at 1-month post-radiotherapy to predict late declines QOL at 24 months. A total of 898 patients were within the initial cohort, 94% had evaluable QOL at 24 months. On MVA, after controlling for age, baseline function, PSA, Gleason score, T-stage, prostate volume, and RT technique, an early MCD was the strongest predictor of late MCD at 24 months in all assessed domains and radiation modalities: odds ratio (OR) 3.7 [95% CI 2.2-6.4] for urinary irritation, OR 4.5 [2.9-6.9] for urinary incontinence, OR 2.4 [1.6-3.5] for bowel, OR 3.7 [2.5-5.5] for sexual function, and OR 3.4 [2.3-4.9] for hormone. Within the validation cohort of 259 patients, 83% had evaluable QOL at 24 months. Early declines of a MCD were again associated with late declines noted across all domains of QOL: OR 3.1 [95% CI 1.7-5.8] for urinary irritation, OR 2.7 [1.5-4.8] for urinary incontinence, OR 2.0 [1.1-3.7] for bowel, OR 4.0 [2.1-7.7] for sexual function, and OR 3.0 [1.2-7.3] for hormone. Early QOL decline was the strongest predictor of QOL impacts at 2 years across all domains and this appeared consistent across standard radiation treatment modalities. This was externally validated within these domains suggesting early declines in QOL are surrogates and predict for late declines.Abstract 141; TableIncidence and Correlation of an MCD in Early and Late QOLEPIC DomainEPIC MCD ThresholdEarly Decline MCDLate Decline MCDOR [95% CI]Early Decline MCDLate Decline MCDOR [95% CI]Initial CohortValidation CohortUrinary Irritative678%36%3.7 [2.2-6.4]63%39%3.1 [1.7-5.8]Urinary Incontinence7.537%24%4.5 [2.9-6.9]32%41%2.7 [1.5-4.8]Bowel554%29%2.4 [1.6-3.5]41%26%2.0 [1.1-3.7]Sexual1136%41%2.9 [2.3-3.8]30%49%2.4 [0.89-6.6] Open table in a new tab

Malignant tumours of temporomandibular joint

BackgroundMalignant tumours of the temporomandibular joint (MTTMJ) are extremely rare. Studies describing its unique epidemiology, clinicopathological features, treatment and prognosis comprehensively are limited. To address these issues, current investigation was performed.MethodsA retrospective research was carried out by using population-based data from the Surveillance, Epidemiology, and End Results database (1973–2016).ResultsData for a total of 734 patients, including 376 men and 358 women, was found. The median age was 47 years. The 5-year and 10-year disease specific survival (DSS) rates were 69.2 and 63.6%, respectively. Significant differences in DSS were found according to age, race, tumour type, AJCC/TNM stage, surgery, radiotherapy, chemotherapy and different treatment modalities (P < 0.05). In the multivariate survival analysis, age > 44 years and AJCC stage III and IV were associated with poor DSS.ConclusionMTTMJ was mostly found in white people with a median age of 47 years without any sex predominance. Patient’s age and AJCC stage was independent predictor of DSS.

Exploring the gamma surface: A new method for visualising modulated radiotherapy quality assurance results.

This work presents a novel method of visualising the results of patient-specific quality assurance (QA) for modulated radiotherapy treatment plans, using a three-dimensional distribution of gamma pass rates, referred to as the "gamma surface". The method was developed to aid in comparing borderline and failing QA plans, and to better compare patient-specific QA results between departments. Gamma surface plots were created for a representative sample of situations encountered during patient-specific QA. To produce a gamma surface plot, for each QA result, gamma pass rates were plotted as a heat map, with dose difference on one axis and distance-to-agreement on the other. This involved the calculation of 100×100 gamma pass rates over a dose difference and distance-to-agreement grid. As examples, five 220×680 arrays of dose points from radiotherapy treatment plans were compared against measurement data consisting of 21×66 arrays of dose points spaced 10mm apart. The gamma surface plots facilitated the rapid evaluation of criteria combinations for each plan, clearly highlighting the difference between plans that are modelled and delivered well, and those that are not. Large scale features were also evident in each surface, hinting at potential over-modulation, systematic dose errors, and small or large scale areas of disagreement in the distributions. Gamma surface plots are a useful tool for investigating QA failures and borderline results, and have the capacity to grant insights into treatment plan QA performance that may otherwise be missed.

External Beam Versus Brachytherapy as Adjuvant Radiation Therapy Modality in Patients with Stage II Endometrial Cancer: A Single Institution Experience

Current NCCN guidelines allow for the physician to choose between EBRT, brachytherapy, or a combination of both to treat FIGO stage II endometrial cancer. Physicians will typically choose the type of treatment based off of other risk factors such as grade, histology, size, depth of myometrial invasion, age, and presence of lymphovascular invasion. Henry Ford has a large database of patients who have been treated for endometrial cancer with adjuvant radiation following surgery and we sought to use this database to explore this area. To determine the impact of adjuvant radiation treatment (RT) modality on overall survival (OS), recurrence-free survival (RFS), and disease-specific survival (DSS) in patients with FIGO stage II uterine endometrioid carcinoma (EC). Our prospectively-maintained database was quired for women with stage II uterine EC who underwent hysterectomy between 1990 and 2018. 100 patients were identified. None received adjuvant chemotherapy. OS, RFS, DSS were all calculated from the date of surgery by use of Kaplan-Meier analysis. Cox regression analysis was used to examine risks associated with changes in OS, RFS, or DSS. The median follow-up time for the study cohort was 110.6 months, and the median age was 66 years. Lymphadenectomy was performed in 78%, peritoneal cytology in 85%. On pathology, 42% of patients were grade 1, 39% grade 2, and 19% grade 3. Adjuvant treatment was external beam radiation therapy (EBRT) alone in 15% of patients, HDR vaginal cuff brachytherapy (BT) alone in in 29% and both in 56% of patients. 5-year RFS for the study cohort was 77%, DSS was and OS was 70%. On multivariate analysis grade 3 vs 1 was a significant predictor for OS (HR 3.11, p 0.0228), RFS (HR 5.1, p 0.0333), but not DSS (HR 6.06, p 0.12). Radiation treatment modality (EBRT, BT, or both) were not found to be significant predictors for any of survival endpoint. In our group of stage II endometrial cancer patients adjuvant RT modality was not predictive of OS, RFS, or DSS. The only independent significant predictor in this group was grade 3 vs 1, and this was only significant for OS and RFS.

Radiation Treatment Modality and Dosimetric Factors Matter an Achieving a Pathologic Complete Response in the Treatment Of Rectal Cancer

Radiation Treatment Modality and Dosimetric Factors Matter an Achieving a Pathologic Complete Response in the Treatment Of Rectal Cancer

Effects of gas-filled temporary breast tissue expanders on radiation dose from modulated rotational photon beams

Gas-filled temporary tissue expanders (TTEs), implanted to assist in post mastectomy breast reconstructions, are expected to produce increased dosimetric uncertainty in breast radiotherapy treatments, due to their containing both a substantial metallic component and a comparatively large volume of gas. This study therefore builds on previous investigations of the dosimetric effects of gas-filled TTEs in static photon and electron beams, by examining the effects of these implants on dose distributions from common modulated rotational treatment techniques; volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT). Radiochromic film measurements were used to evaluate the accuracy of VMAT and HT dose calculations, for a humanoid phantom augmented with a sample Aeroform CO2-filled TTE (AirXpanders Inc, San Jose, USA) as well as purpose-designed and 3D printed “breast tissue.” Results showed that the TomoTherapy Hi-Art VoLO convolution-superposition algorithm (Accuray Inc, Sunnyvale, USA) produced comparatively accurate calculations of treatment dose within this complex phantom, including immediately anterior and posterior to the TTE. The Varian Eclipse Acuros (AXB) algorithm generally showed better agreement with the film measurement than the Varian Eclipse AAA algorithm (Varian Medical Systems, Palo Alto, USA), although the film measurements showed regions of 5% to 10% disagreement with both AAA and AXB in the dosimetrically-challenging region on the anterior side of the implant. Although the Aeroform CO2-filled TTE has substantial and obvious effects on the downstream dose from a static photon beam, the results of this study showed how inverse-planning of modulated rotational radiotherapy treatments can produce modulated fluence distributions that compensate for the dramatic density heterogeneities in the implant. Despite some disagreements with the planned dose, all film measurements showed that the use of inverse-planned modulated rotational photon beams resulted in comparatively homogeneous coverage of the radiotherapy target, in the complex patient-like phantom with a gas-filled TTE. Due to the importance of matching each planned fluence distribution to the density distribution within each TTE, careful use of available 3D imaging techniques is advisable, when modulated rotational radiotherapy treatments are delivered to patients with gas-filled TTEs.

MP67-19 DUCTAL ADENOCARCINOMA OF THE PROSTATE: A SYSTEMATIC REVIEW AND META-ANALYSIS OF INCIDENCE, PRESENTATION AND MANAGEMENT

MP67-19 DUCTAL ADENOCARCINOMA OF THE PROSTATE: A SYSTEMATIC REVIEW AND META-ANALYSIS OF INCIDENCE, PRESENTATION AND MANAGEMENT

Impact of radiopacified bone cement on radiotherapy dose calculation.

Background and purposeRadiopacifiers are introduced to bone cements to provide the appearance of bone in kilovoltage (kV) radiographic images. For higher energy megavoltage (MV) radiotherapy treatment beams, however, these radiopacifiers do not cause a bone-like perturbation of dose. This study therefore aimed to determine the impact of the barium-contrasted plastic-based cement materials on radiotherapy dose calculations.Materials and methodsThe radiological properties of a physical sample of bone cement were characterised by computed tomography (CT) imaging and transmission measurements. Monte Carlo simulations of percentage depth-dose profiles were performed to determine the possible dose error for MV treatment beams. Dose differences were then investigated for clinical volumetric modulated radiotherapy treatment plans, with and without density overrides applied.ResultsDifferences of up to 7% were observed at the downstream interface of a 0.6 cm thick bone cement layer, compared to bone. Differences in planning target volume dose-volume metrics varied between −0.5% and 2.0%.ConclusionBefore planning radiotherapy treatments for patients who have undergone cranioplasty, every effort should be made to identify whether a radiopacified bone cement has been implanted. Density overrides should be applied to minimise dose calculation errors, whenever bone cement is used.