Conformal Technique Research Articles

Spatiotemporal microplastic occurrence study of Harike wetland, A Ramsar wetland of India

Ramsar wetlands are one of the least investigated areas for microplastic contamination. Harike wetland is located downstream of the confluence of the Beas and Sutlej rivers. Rivers are nature's drainage systems, which collect waste from everywhere and move ahead. On the same note, the Harike wetland, the largest wetland in North India, is an ideal home for migratory birds and aquatic animals. The water in the canal and the fish living within it have been examined for microplastics. Results revealed that the number of microplastics did not significantly differ between sites 1 and 2, but showed a seasonal variation with higher levels observed in the winter season compared to summer and the rainy season. The most common types of plastics detected in the wetland and canal were HDPE and nylon, which were further analyzed using conformational tests, ATR-FTIR, and GC-MS techniques. Additionally, microplastics measuring less than 5mm in size were recovered from the gut of Cyprinus carpio fish, with a 7% recovery rate from the total number of fish analyzed. Although this percentage may seem low, it cannot be ignored given the potential impact on the aquatic environment. This percentage may be less, but it is not ignorable. Indeed, the amount of poorly managed plastic garbage generated by people living around or illegal outskirts garbage dumping near rivers and tributaries is a potential source of aquatic debris.

Palliative Radiotherapy for Symptomatic Primary Tumors in Patients With Locally Advanced Breast Cancer.

Breast cancer remains a significant health concern for women, with a significant number of women facing unresectable, symptomatic, and advanced disease that severely affects their quality of life. Palliative radiotherapy (RT) is a well-established modality for managing such cases and alleviating symptoms. Recent advancements in systemic therapies and the resulting increase in long-term survival rates have not only heightened the need for retreatment in certain patients, but have also emphasized the importance of achieving durable local control. Additionally, inconsistencies in RT referral timing and variations in disease severity and extent contribute to diverse RT objectives and expected outcomes. The optimal dose fractionation for RT remains underexplored. Furthermore, a deeper understanding of breast radiobiology, along with the introduction of ultra- and moderately hypofractionated regimens and the widespread adoption of conformal techniques such as intensity-modulated RT, has diversified the approaches in RT dose and target volume. This review aimed to provides a comprehensive summary of the current evidence on the efficacy, outcomes, and toxicity profiles of palliative RT for symptomatic breast cancer. It highlights the need for more optimized regimens and further research to address the evolving treatment landscape and differing expectations of patients and physicians regarding RT.

Some mathematical assumptions for accurate transformation parameters between WGS84 and Nord Sahara geodetic systems

Abstract The transformation of coordinates between different geodetic datums has been a common practice within the geospatial profession. Relating different geodetic datums mostly involves the use of conformal transformation techniques, which could produce results that are not very often satisfactory for certain geodetic, surveying, and mapping purposes. This has been attributed to the inability of the conformal models to resolve the lack (non-exhaustivity) and the heterogeneity of double points existing within the Algerian local geodetic networks. Indeed, the Algerian geodetic network is divided into two main zones completely different in accuracy and points exhaustivity. The North is better and well defined in precision; on the other hand, the South is poorly defined because of the lack of heterogeneity of the points. Mathematical algebraic methods give closed-form solutions to geodetic transformation problems, requiring a high-level computer programming background. In everyday usage, the closed-form solutions are much simpler and have a higher precision than earlier procedures. Thus, it can be predicted that these new solutions will find their place in practice. The present work deals with an important theoretical problem of geodesy: we are looking for a mathematical dependency between two spatial systems using common pairs of points whose coordinates are given in both systems. In geodesy and photogrammetry, the most often used procedure to move from one coordinate system to another is the 3D, seven-parameter similarity transformation (Bursa–Wolf, Molodensky–Badekas, and Helmert).

Dosimetric Comparison of Three-Dimensional Conformal, Intensity-Modulated Radiotherapy, Volumetric Modulated Arc Therapy, and Dynamic Conformal Arc Therapy Techniques in Prophylactic Cranial Irradiation

Dosimetric Comparison of Three-Dimensional Conformal, Intensity-Modulated Radiotherapy, Volumetric Modulated Arc Therapy, and Dynamic Conformal Arc Therapy Techniques in Prophylactic Cranial Irradiation

Locoregional Ablative Radiation Therapy for Patients With Breast Cancer Unsuitable for Surgical Resection

Breast cancer patients unsuitable for surgical resection are typically managed with palliative systemic therapy alone. We report outcomes of 5-fraction ablative radiotherapy for non-resected breast cancers. Retrospective analysis of an institutional registry of breast cancer patients unsuitable for resection who underwent 35-40 Gy/5 fractions to the primary breast tumour and/or regional lymph nodes from 2014-2021. Primary outcomes were cumulative incidence of local failure (LF) and grade ≥3 toxicity (CTCAE v5.0). We reviewed 57 patients who received 61 treatment courses (median age of 81 years, range 38-99). Unresectable tumour (10%), patient refusal (18%), medical inoperability (35%), and metastatic disease (37%) were the causes of not having surgery. Five patients (8%) had previously undergone adjuvant locoregional radiotherapy. Fifty-four percent (n=33/61) of treatment courses targeted the breast only, 31% (n=19/61) both the breast and lymph nodes, and 15% (n=9/61) the lymph nodes only. Sixty-seven percent (n=35/52) of the courses that targeted the breast were delivered with partial breast irradiation and 33% (n=17/52) with whole breast radiotherapy (median dose of 25Gy in 5 fractions) ± simultaneous integrated boost to the primary tumour. Most primary tumours (65%, n=34/52) and target lymph nodes (61%, n=17/28) were treated with a dose of 35 Gy in 5 fractions. Most treatments (52%) were delivered with intensity-modulated radiotherapy (IMRT). Radiotherapy was delivered daily (20%), every other day (18%), twice weekly (36%) or weekly (26%). The 2-year cumulative incidence of LF was 11.4% and grade≥3 toxicity was 15.1%. The grade ≥3 toxicity was 6.5% for IMRT treatments, versus 7.7% for non-IMRT treatments targeting partial breast and/or lymph nodes (HR 1.13, P=0.92), versus 38.9% for non-IMRT treatments targeting the entire breast (HR 6.91, P=0.023). All grade ≥3 toxicity cases were radiation dermatitis. No cases of brachial plexopathy were observed. 35-40 Gy in 5 fractions is a safe and effective breast stereotactic body radiotherapy regimen and may be an attractive option for patients who are not surgical candidates. Highly conformal techniques (i.e. IMRT or partial breast irradiation) were associated with a reduced risk of toxicity and should be the preferred treatment approaches.

(Keynote) ALD Challenges and Opportunities in Light of Future Trends in Si-Based Nanoelectronics

To enable CMOS transistor density scaling following Moore’s Law, device architectures transitioned in the past decade from the historical 2D planar transistor to FINFET. The next innovation touted for the 3nm node is a 3D stacked gate-all-around architecture in combination with a backside power delivery network. For further scaling, stacking nmos and pmos, the so-called complementary-FET (CFET) design, is envisaged to happen in 2030. The shrinking device dimensions of the interconnects require also new metallization schemes to tackle the RC challenge, such as Cu replacements materials in a direct metal etch integration scheme. Beyond the CFET era, one envisages the introduction of 2D-grown channel materials that will pave the way for further scaling. A broad variety of complementary deposition techniques will be needed to enable the above-mentioned novelties; among them ALD that will play a crucial role.A similar trend towards stacking functional cells can be observed in various memories, such as the emerging memories that aim to bridge the gap between DRAM and NAND, thereby enabling fast data storage and retreival for real-time processing in connected devices at low cost. These memories are based on phase change, filamentary, magnetic, or ferroelectric mechanisms and often use multi-element materials. They have been extensively explored in 2D capacitor or transistor based devices, but for further density scaling 3D device designs are needed where a conformal deposition technique such as ALD is required. Cell scaling challenges also hold for the traditional DRAM which lead to exploring 3DDRAM integration routes. One viable pathway for scaling implies the replacement of the typical Si-channel based transistor by a deposited semiconductor oxide channel. Ultimate 3DDRAM implementation would require a conformal deposition of that channel.In this presentation, we will discuss the opportunities and challenges of ALD in a 3D-evolving device landscape where new materials will play a key role.

Long-Term Outcomes After Abdominal Radiation for Wilms Tumor: A 20-Year Experience.

As radiation therapy (RT) for Wilms tumor (WT) evolves with more conformal techniques, it is necessary to evaluate patterns of failure and toxicity. We sought to determine the rate of local failure (LF) after abdominal RT in WT, specifically focusing on those with contained rupture treated with whole abdominal and pelvic RT (WAPRT) vs flank RT. Secondary objectives were to determine overall survival (OS), distant failure (DF), and late toxicities. A single institution retrospective study of 54 pediatric patients with WT treated with abdominal RT between May 2000 and October 2022. LF and DF were calculated through cumulative incidence function and OS by Kaplan-Meier method. The median age was 4.5 years and the median follow-up was 6 years. Most patients (91%) had favorable histology. Only 1 patient experienced LF, 15 months from completion of RT (cumulative incidence 2% at 5y). All patients who received unilateral flank radiation for contained rupture/spillage (n=13) experienced long-lasting intra-abdominal tumor control. A total of 5 patients experienced a DF at a median of 7 months, all in the lung. No patient relapsed in the lungs after upfront whole lung irradiation (n=16). OS was 96% at 5 years. Among 28 patients who followed through puberty, 4 female patients with prior WAPRT experienced hormonal irregularities/infertility. Unilateral flank radiation may be a viable alternative to WAPRT for contained rupture/spillage and should be further explored prospectively. Our results may also be utilized in the future for outcome and toxicity comparison as conformal radiation techniques evolve.

Diamond-based detection systems for tomorrow's precision dosimetry

Radiation therapy is now widely applied for cancer care. For an effective and safe treatment, accurate dosimetry is mandatory. The evolution and widespread adoption of modern dynamic and conformal radiotherapy techniques have imposed several challenges from a dosimetric perspective. Commonly employed radiation beams include high-energy (6–18 MeV) photons or electron beams for external treatments, as well as low-energy (tens of keV) photons for intraoperative procedures. Recently, the emerging FLASH technique is posing additional challenges in the field of dosimetry. This work involved the fabrication and test of a custom-made diamond dosimeter. The detector was exposed to high-energy and low-energy X-ray radiation, as well as to FLASH beams, highlighting its versatility under all these conditions. The sensitivity of the dosimeter was estimated to be 73.96 nC Gy−1 mm−3 under MeV photons and 2.76 nC Gy−1 mm−3 under FLASH MeV electrons. Furthermore, this paper aims to illustrate the accuracy of dosimetry using the synchronous detection technique, enabling real-time monitoring of the dose delivered in each pulse, a crucial aspect for the beam diagnostics in the emerging FLASH radiotherapy.

A new insight on relative permeability modifier as conformance control in carbonate reservoir

The primary issue of high-water cuts in exploiting carbonate fields poses significant challenges and requires an immediate solution. The approach to tackle the root cause of this problem is reservoir conformance control. Conventional conformance control treatments, such as polymer-based materials, are ineffective and incompatible with the unique properties of carbonate reservoirs. Textural heterogeneity in carbonate leads to heterogeneity in the distribution of storage and flow properties that may govern changes in saturation patterns. The percolation of gas-water flow in carbonate highly depends on the pore structure. Conformance control refers to managing fluid movement within a reservoir to optimize production and reduce unwanted fluid production. The major challenge of water conformance control for carbonates using chemical treatment is the compatibility of the polymer system with the rock and fluid settings. This paper reviews current research on conformance control methods, including chemical and mechanical techniques. The effectiveness of various conformance control methods was evaluated based on their ability to improve sweep efficiency, reduce water production, and increase hydrocarbon recovery in different reservoir types. The review also discusses the challenges of implementing conformance control techniques, such as formation damage and fluid mobility issues. Overall, the paper concludes that successful implementation of conformance control strategies requires a thorough understanding of reservoir characteristics and planning to ensure optimal results. The findings of this study provide valuable insights into developing effective conformance control techniques that can improve hydrocarbon recovery and optimize reservoir performance. The results of this study provide critical insight into using efficient and operationally low-risk materials to reduce water cuts in the strong water drive carbonate reservoir.

RADT-21. LINEAR ACCELERATOR BASED RADIOSURGERY WITH DYNAMIC CONFORMAL ARCS FOR PATIENTS WITH MULTIPLE BRAIN METASTASES: A PROSPECTIVE COHORT STUDY

Abstract PURPOSE Linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) is gaining popularity as an alternative due to its high delivery efficiency and improved accessibility. This study focuses on the radiosurgery protocol of a single institution, utilizing single-isocenter multi-target SRS treatment with an inverse-optimized dynamic conformal arc technique. Materials & METHODS A prospective cohort study was conducted from August 2020. The study protocol was approved by the Research Ethics Committee. Patients with brain tumors referred for SRS were treated based on the indications. Prescription doses were determined by target size and radiation oncologists. The protocol included a 1-2 mm expansion of tumors for the planning target volume (PTV), with a requirement of at least 85% PTV coverage. At least three non-coplanar arcs are needed. Competing risk survival analysis was used to assess the cumulative incidence of failure. RESULTS A total of 57 patients with 190 brain tumors underwent SRS in this study. 12 patients (21.1%) received at least 2 radiation courses for recurrent lesions. Tumor sizes ranged from 0.45 to 8.0 cm (median 1.41 cm). The maximal dose relation ranged between 71.5% and 91.4% (median 81.6). The conformal index ranged from 1.08 to 2.19 (median 1.19), and the dose gradient index ranged from 2.19 to 6.95 (median 3.59). The 1-year cumulative incidence of local failure and intracranial distant failure rates were 10.8% and 35.6%, respectively. CONCLUSION LINAC-based SRS using dynamic conformal arcs achieves optimal tumor coverage and a high dose gradient with ease. It demonstrates a low rate of local failure, effectively protects normal brain tissue, and allows for the postponement of whole brain radiotherapy, enabling patients to maintain a normal quality of life. In conclusion, LINAC-based SRS with dynamic conformal arcs may be a beneficial treatment option for brain metastases, even with a high lesion count, particularly in institutions equipped with LINAC.

3D2: Three Decades of Three-Dimensional Dosimetry

The development of three-dimensional (3D) dosimetry was motivated by its promise as an effective methodology for the validation of the complex dose distributions achieved by modern techniques such as Intensity Modulated and Volumetric Arc Radiation Therapy. 3D techniques were first proposed in the 1980s when clinics were just starting to move from two-dimensional contour plan based delivery to more conformal techniques. Advances in dosimeter materials, readout systems, and workflow and software systems for the registration and analysis of the volumetric dose data have made 3D dosimetry more attainable, yet to date it has not made major inroads into the clinic. This keynote address will highlight some 3D dosimetry developments over the years, many of which were first revealed through the past twelve International Conferences on 3D and Advanced Radiation Dosimetry (IC3Ddose). These conferences resulted in the publication of more than 130 didactic review articles and over 650 proffered research papers, the majority openly available on the internet (years before the current drive to publishing in open access journals). In this joint keynote address to the IC3Ddose community (at the end of its conference) and to attendees of the Canadian Organization of Medical Physicists annual scientific meeting (at its start), I will briefly review the radiation sensitive materials used for 3D dosimetry, the imaging systems required to read out the volumetric dose information, the workflows and systems required for efficient analysis, and the protocols required for reproducible dosimetry, and how the dosimetry has come into the clinic. The address includes some personal reflections of the motivational and practical changes in 3D dosimetry over time. And as we are all meeting in person for the first time in over two years, the address will end with some observations on the importance of conferences for the exchange of ideas and associated debate necessary for scientific advancement.

An Analytical Study to Determine Dose-Volume Threshold for Radiation Induced Hypothyroidism.

Objective: To determine radiation dose volume threshold in predicting the development of hypothyroidism in cancer patients following neck irradiation. Methods: This is a cross sectional follow up study for patients who had been previously irradiated, prior to enrolment in the study. We have done thyroid dose-volumetric analysis on 120 histologically proven cancer patients in the age group of 18-75 years who received neck irradiation as a part of their definitive or adjuvant radiotherapy with three-dimensional conformal or intensity-modulated radiotherapy technique (3D -CRT or IMRT) and completed at least six months post-radiotherapy. Primary tumor sites included carcinoma or lymphoma of the head and neck, breast, cervical, and upper thoracic esophagus, requiring neck irradiation. Results: The proportion of patients who tested positive for Radiation induced hypothyroidism (RIHT) was found to be 40%, with clinical hypothyroidism and subclinical hypothyroidism being 25.8% and 14.2%, respectively. Time to develop hypothyroidism peaks around two years. Mean thyroid gland dose (Dmean) >28 Gy, thyroid gland volume receiving 40 Gy dose (i.e. V40) >49% and age <50 years were found to be significant risk factors for the development of RIHT on binary logistic regression. RT dose >50 Gy and thyroid gland volume spared from 40 Gy (i.e. VS40) < 2.12cm3 were statistically significant predictors for RIHT on chi-square and (Receiver operating characteristic) ROC curve analysis respectively but not on regression analysis. Conclusion: Dose-volume threshold for the thyroid gland as Dmean <28 Gy and V40 <49% may prevent the development of RIHT.

Formation of resistant starch and cracker products from leftover rice in Saudi Arabia

Food leftovers are a worldwide concern and the Food and Agriculture Organization reported about 400 billion USD worth of food is wasted yearly. In the Kingdom of Saudi Arabia, food waste is increasing; the loss is about 33.6% of the rice commodity only. To achieve sustainable development goals including zero hunger and sustainable consumption, the current investigation aimed to study the recycling possibilities of rice leftovers through the production of resistant starch (a nutraceutical active component). Proximate analysis, in vitro digestibility (rapidly, slowly, and resistant starches), and conformational techniques (SEM, FTIR, and DSC) were accomplished before and after treating heated or not samples with acetic, citric, and tartaric acids. Also, crackers were produced from rice starch and its sensory evaluations were completed. Results reported variations in starch content between the controls and acid treatments, but interestingly, amounts of protein, and fiber were not different. The highest production of resistant starch (more than 35%) was when treated with tartaric acid and heat treatment, followed by citric acid and heat treatment (32.5%), then acetic acid and heat treatment (28%). The FTIR pictograms revealed the acetylation of heat and acid-treated rice samples. The gelatinization enthalpy (ΔH) decreased from 10.51 to 7.81 J/g for control and treated rice by acetic acid without heat. Surprisingly, the panelists reported no differences in the sensory evaluations of crackers produced from treated rice with a high content of resistant starch, which considered as functional food. These findings help achieve food sustainability through commercial-scale functional food production.

Re-irradiation in clinical practice: Results of an international patterns of care survey within the framework of the ESTRO-EORTC E2-RADIatE platform

BackgroundRe-irradiation is an increasingly utilized treatment for recurrent, metastatic or new malignancies after previous radiotherapy. It is unclear how re-irradiation is applied in clinical practice. We aimed to investigate the patterns of care of re-irradiation internationally. Material/MethodsA cross-sectional survey conducted between March and September 2022. The survey was structured into six sections, each corresponding to a specific anatomical region. Participants were instructed to complete the sections of their clinical expertise. A total of 15 multiple-choice questions were included in each section, addressing various aspects of the re-irradiation process. The online survey targeted radiation and clinical oncologists and was endorsed by the European Society for Radiotherapy and Oncology (ESTRO) and the European Organisation for Research and Treatment of Cancer (EORTC). Results371 physicians from 55 countries across six continents participated. Participants had a median professional experience of 16 years, and the majority (60%) were affiliated with an academic hospital. The brain region was the most common site for re-irradiation (77%), followed by the pelvis (65%) and head and neck (63%). Prolonging local control was the most common goal (90–96% across anatomical regions). The most common minimum interval between previous radiotherapy and re-irradiation was 6–12 months (45–55%). Persistent grade 3 or greater radiation-induced toxicity (77–80%) was the leading contraindication. Variability in organs at risk dose constraints for re-irradiation was observed. Advanced imaging modalities and conformal radiotherapy techniques were predominantly used. A scarcity of institutional guidelines for re-irradiation was reported (16–19%). Participants from European centers more frequently applied thoracic and abdominal re-irradiation. Indications did not differ between academic and non-academic hospitals. ConclusionThis study highlights the heterogeneity in re-irradiation practices across anatomical regions and emphasizes the need for high-quality evidence from prospective studies to guide treatment decisions and derive safe cumulative dose constraints.

Modeling Acute Chemoradiotherapy (CRT) Diarrhea Severity Using Automatically Contoured Small Bowel

Acute severe diarrhea is a common toxicity in rectal cancer patients receiving CRT. A better understanding of the radiation tolerance of the small bowel is needed especially for novel radiation drug combinations. We investigate the dose impact by providing auto-contoured small bowel, using data from the ARISTOTLE phase III trial ISRCTN: 09351447. A subset of participants (n = 93/564) with locally advanced rectal cancer in the ARISTOTLE trial testing the addition of concurrent irinotecan (n = 48) to neoadjuvant capecitabine (n = 45) CRT (45/25 Gy/fx), in an MRI defined high risk of loco-regional failure. CRT was delivered with conformal techniques. Diarrhea was measured using CTCAE v4.0 weekly. We applied an AI-based auto-contouring model to segment the small bowel on planning CT. The small-bowel DVH parameters were combined with the treatment arm, age, sex and MRI-defined tumor stage in a linear regression (LR) model to predict acute diarrhea severity. Explainable Shapley values (conditional marginalized expectation of a machine learning model per feature) were used to quantify the independent and normalized impact of radiation dose vs Irinotecan on the likelihood of severe diarrhea. The auto-contouring model accuracy was consistent with clinical practice (mean dice coefficient = 0.739) and clinically acceptable when reviewed by clinicians. The treatment arm, MRI-defined T stage and small-bowel mean dose were found to be independently correlated to the diarrhea severity (p<0.001). V30Gy showed the strongest correlation to diarrhea severity in all the DVH parameters. The LR using the three variables yielded mean AUC scores of 0.898 (95% CI: [0.831,0.958]) on predicting Grade 2 and higher diarrhea, and 0.774 (95% CI: [0.678,0.869]) on predicting Grade 3 diarrhea based on 10-fold cross-validation. Shapley values showed that V30Gy>30.56 cm3 increases the likelihood of more severe diarrhea against the average (grade = 1.03) in the cohort. The impact of irradiation will be larger than the usage of Irinotecan within the patients with V30Gy >160.93 cm3. We accurately modelled acute diarrhea (AUC = 0.90) for rectal cancer patients receiving CRT using AI-contoured small-bowel structures. The treatment arm and small-bowel dose were independently correlated to the diarrhea severity. The explainable model allowed us to quantify the impact of radiation dose, usage of irinotecan, and its combination, with a threshold of V30Gy = 160.93 cm3 yielding an equivalent impact. We will be extending the analysis to the whole trial cohort to improve the statistical power.

Radiotherapy vs. Cystectomy for Treatment of Muscle Invasive Bladder Cancer in Very Elderly Patients

Radical cystectomy (RC) has long remained the principal treatment of muscle invasive bladder cancer (MIBC). It is, however, associated with significant morbidity, long recovery, and reported worse overall and cancer specific survival, particularly for the very elderly (age > = 80). Bladder preservation with transurethral resection of bladder tumor (TURBT) followed by radiotherapy (RT) +/- concurrent chemotherapy (ChT) is regarded as a curative-intent alternative to RC in well-selected patients. The optimal treatment strategy remains unclear in very elderly patients. We hypothesize that outcomes following RT vs RC are clinically equivalent for treatment of MIBC in very elderly patients. Patients > = 80 years old with T2-T4 N0-N1 bladder cancer treated definitively with RT versus RC were included. Exclusion criteria included history of pelvic RT, prior cystectomy, or palliative treatment intent. Clinicopathologic and treatment-related details, as well as clinical outcomes and toxicities were retrospectively abstracted. Kaplan-Meier analyses were performed. At a median follow-up of 17 months (range 0.25-190), 47 patients received RT vs 83 patients who underwent RC with median age of 86 years (80-97) vs 83 years (range 80-91) (p<0.01), respectively. Median Charlson Comorbidity Index was similar between groups (p = 0.35) with median 7 for both cohorts, predicting 0% estimated 10y survival. Most patients had cT2 tumors (91% vs 99%, p = 0.06), cN0 nodal status (96% vs 100%, p = 0.06), and urothelial carcinoma histology (79% vs 90%, p = 0.22). Most RT patients received concurrent ChT (90%) and a minority of RC patients received neoadjuvant ChT (16%). 70% of RT pts had complete TURBTs prior to RT. Common RT regimens were 50-55 Gy in 20-25 fractions or 60-64.8 Gy in 30-36 fractions, using IMRT (89%) or 3D conformal (11%) technique. Overall survival for RT vs RC at 1- and 2- years was 79% vs 85% and 57% and 69%, respectively (p = 0.20). Locoregional control at 1- and 2-years was 73% vs 70% and 63% vs 66% (p = 0.59), respectively. Progression free survival at 1- and 2-years was 69% vs 66% and 52% vs 54% (p = 0.75), respectively. No RT patients went on to receive salvage cystectomy. Treatment complications are listed in Table 1; the Clavien Dindo classification system was used to describe acute surgical complications of RC and the Common Terminology Criteria for Adverse Events (CTCAE) Dictionary v5.0 was used for acute and late toxicity of RT. In the very elderly, RT (with or without concurrent ChT) offers survival and locoregional control rates comparable to RC, with a favorable side effect profile. RT should be offered for definitive management of non-metastatic MIBC as an alternative to RC in selected, well- informed, and compliant very elderly patients.

Clinical Sequalae of Initial Insurance Denials in a Large Academic Radiation Oncology Center

The objective of this study is to investigate the clinical sequalae of initial radiation oncology insurance denials. The hypothesis is that while the majority of initial insurance case denials are ultimately overturned, there are potential clinical implications to these initial denials. Data were extracted from an institutional registry of patient cases initially denied authorization by their insurers from January 2022 to December 2022. Chi-Square tests using statistical software were employed. Two hundred six cases from November 2021 to December 2022 were identified. The majority (n = 199 [96.6%]) of insurers were commercial payers, while 7 (3.4%) were Medicare/Medicare Advantage. 161 (78.1%) patients were <65 years of age, and 45 (21.8%) 65 or older. One hundred forty-one (68.4%) cases were metastatic, 60 (29.1%) definitive, and 5 (2.4%) were recurrent. Of the 206 cases, 127 (61.6%) cases were ultimately successful in authorization of the ordered treatment without any change to the requested treatment technique or prescription dose after P2P (Peer to Peer review), second-level appeal, comparison plan submission, employer request, insurance carrier change, and/or external appeal, and 56 (27.2%) cases were authorized though with insurer-requested modification to radiation treatment technique and/or prescription dose. Of 21 cases with a requested change in prescription dose, the median decrease in biologically effective dose (BED) was 24 Gy (range: 2.3-51). Of 58 cases with requested change in RT technique, 20 (34.5%) changed from IMRT to 3D-CRT, 16 (27.6%) SBRT to 3D, 15 (25.9%) SBRT to IMRT, 6 (10.3%) SBRT to 2D, and 1 (1.7%) 3D-CRT to 2D. 19 (9.2%) cases remained unauthorized by the insurer but proceeded with treatment via departmental administrative clearance. Of 196 cases which went on to treatment, 72 (36.7%) cases were delayed for a mean of 7.8 days and median of 5 days (range: 1-49). P2P was performed by the treating radiation oncologist in 169 (82.0%) cases, of which 78 (46.1%) were successful in authorization of the ordered treatment. Of the 91 unsuccessful cases, 62 (68.1%) second-level appeals were performed, of which 39 (62.9%) were successful in overturning denied authorization. Of the 23 cases not authorized either through P2P or second-level appeal, 3 (13.0%) cases were successful in authorization of the requested treatment via employer request, external appeal through an independent review organization, or insurance carrier change. Our institutional analysis suggests that while the majority of initial insurance case denials are ultimately overturned without any change to the requested treatment technique or prescription dose through a number of requests made by the insurer to the radiation oncologist, there are clinical implications with a significant percentage of case denials leading to treatment delays, decrease in prescription BED, and less conformal treatment technique.

Is it the Type of Axillary Surgery or the Number of Removed Lymph Nodes That Increases the Risk of Breast Cancer Related Lymphedema (BCRL)? Results from a Prospective Screening Trial

Axillary surgery has been identified as the main risk factor for BCRL regardless the delivery of regional nodal radiation (RLNR). Yet it remains unknown if it is the type of axillary surgery or the number of removed lymph nodes (LN) that increases BCRL risks. Between 2008 and 2021, 3,350 patients (pts) who received surgery for breast cancer were enrolled in a lymphedema screening trial. Patients with bilateral breast cancer or without axillary surgery were excluded. Perometry was used to assess limb volume preoperatively in all patients. BCRL was defined as a ≥10% relative arm-volume increase arising >3 months postoperatively. The cohort was divided by axillary surgery type: axillary lymph node dissection (ALND) and sentinel lymph node biopsy (SLNB). Radiation was delivered using 3D conformal technique and RLNR was defined as the usage of anterior supraclavicular field. No hypofractionation was used and doses ranged between 50 and 50.4 Gy in 25-28 fractions. Multivariable Cox proportional hazard models compared the cumulative incidence of BCRL and local failure between different patient groups. After applying inclusion criteria, 2,623 pts were available with overall median follow-up s of 6.1 years. Of the entire cohort, 709 (27%) had ALND with a median of 16 LN removed, while 1,914 (73%) received SLNB only with a median of 2 LN removed. The median number of malignant LN and patients receiving RLNR was higher in ALND group compared to SLNB only group. Frequency distribution analysis showed that the main overlap between ALND and SLNB only groups happen in the range of 3-11 LN removed. Therefore, the primary analysis focused only on pts with 3-11 LN across both groups (n = 690: ALND n = 140, SLNB n = 550). The multivariable model adjusted for BMI, RLNR, age and breast surgery showed that in this group with 3-11 LN removed in both cohorts, ALND remained significantly associated with BCRL (HR: 4.2, p<0.0001). Separate analyses for the entire SLNB only group and ALND groups were conducted to evaluate if the BCRL risk increases per each removed LN within the same axillary surgery group. The multivariable analysis for SLNB only pts(N = 1,914) showed that for each LN removed the risk of BCRL did not increase significantly (HR:1.06, p = 0.3), similarly for ALND group (N = 709) for each LN removed (HR:1.02, p = 0.08). For pts with pathologic N2-N3 disease and clinical node negative without neoadjuvant chemotherapy receiving ALND, the number of LN removed did not significantly improve neither Local control (HR:1.02, p = 0.8) nor distant disease survival (HR:1.01, p = 0.6). ALND procedure per se is the main risk factor for BCRL not the number of LNs removed. For high-risk pts with >N2 disease, aggressive ALND did not improve tumor outcome. De-escalation with targeted axillary sampling followed by RLNR should be evaluated. Future lymphedema research should account for type of axillary surgery instead of number of LNs removed as a factor. (NCT01521741).

Omission of Chest Wall/Scar Boost and Skin Bolus Does Not Increase Risk of Local Recurrence for Breast Cancer Patients

For breast cancer patients receiving postmastectomy radiation (PMRT), little is known about the value of Chest Wall Boost (CWB) and Skin Bolus (SB) across different biological subtypes and patients with high-risk features. We reviewed 2,917 charts of breast cancer patients treated with mastectomy between 2000-2020 at our institution. Only patients treated with PMRT were included. Patients with and without reconstruction were included. Reconstruction types included autologous or single-stage-direct-implant or two stages expanders/implant. PMRT was delivered with 3D conformal technique using photons and conventional fractionation (50-50.4 Gy in 25-28 fractions). CWB using enface electrons and 3-5 mm SB applied every other day were delivered at the discretion of the physician. Primary objectives were locoregional failure (LF) rates between CWB and No CWB groups; SB and No SB groups. Different subgroup analyses exploring the benefits of CWB and SB in different biological subtypes, patients with lymphovascular invasion (LVI+), positive margins (PM) and nipple sparing mastectomy (NSM) were conducted. Secondary objectives were toxicity of CWB and SB on different reconstruction outcomes and PMRT side effects. Logistic and cox regressions were used. A total of 1,103 patients with an overall median follow-up of 7.8 years were available for analysis. Among the entire cohort, 55.4% received CWB, 76% received SB, 48% had LVI, 23% with PM, 41% with NSM, 67% with Luminal A, 15% with Luminal B, 7% with HER2 enriched and 11% with triple negative. The 10 years incidence of LF was 6.5% and 4.0% for CWB and NO CWB, respectively (HR 1.6, p = 0.1); and 5.6% and 5.1% for SB and NO SB respectively (HR 0.9, p = 0.8). Multivariable analysis of LF adjusted for LVI, ECE, grade, tumor size, number of malignant nodes, and biological subtype showed no association of CWB and SB with local control (HR:1.4, p = 0.2 and HR:0.9, p = 0.8), respectively. Subgroup analyses confirmed no association of CWB or SB with improved local control across different biological subtypes, (LVI+), PM and NSM patients. On multivariable level CWB significantly increased reconstruction complications (OR 2.3, p = 0.001, OR 1.7, p = 0.008) for infection/necrosis (I/N) and overall reconstruction failure (ORF), respectively; while SB did not (OR 1.1, p = 0.8, OR 1.0, p = 0.9) for I/N and ORF, respectively. 56 patients needed treatment break, 49 of them (87%) had SB. Both CWB and SB significantly increased the risk of higher grade radiation dermatitis (2-4) in the entire cohort OR 2.1 p = 0.01, and OR 2.3, p = 0.02 for CWB and SB, respectively. CWB and SB did not improve local control across different biological subtypes, patients with LVI, Positive Margins and NSM. CWB significantly increased reconstruction complications and SB increased treatment breaks and radiation dermatitis. These findings do not support routine usage of CWB and SB.

Impact of Neoadjuvant Concurrent Chemoradiation (NACCRT) on Operability and Survival in Locally Advanced Inoperable Breast Cancer

Inoperable locally advanced breast cancers (LABC) are treated with neoadjuvant chemotherapy (NACT). However, many patients remain inoperable after NACT due to an inadequate response. We, therefore, investigated the role of neoadjuvant concurrent chemoradiation (NACCRT) in this setting. Patients with inoperable Stage III LABC were prospectively recruited in the study between May 2017 and December 2021. NACT consisted of 4 cycles of q3weekly Adriamycin (60 mg/m2) and Cyclophosphamide (600mg/m2), and 4 cycles of q3weekly Paclitaxel (175 mg/m2). Concurrent radiotherapy with 6 MV X-rays was given using a 3D conformal technique to a total dose of 46 Gy (2 Gy/fraction, 5 days/week) to the involved breast, axilla, supraclavicular fossa, and internal mammary chain (upper 3 intercostal spaces) along with the first two cycles of paclitaxel. A 0.5 cm bolus was used to boost the skin till the appearance of hyperpigmentation. All patients were assessed for surgery after the completion of the planned neoadjuvant treatment. Adjuvant treatments were given based on the receptor status. The impact of neoadjuvant CTRT on the pathological complete response (pCR), operability, and survival was analyzed. Event-free survival (EFS) and Overall Survival (OS) were analyzed using the Kaplan-Meier method. The study enrolled 202 female patients with a median age of 52 years, with 23.7% having IIIA, 65.3% IIIB, and 10.8% having IIIC disease. Hormone-receptor (HR) positive disease was observed in 90/202 (44.6%) patients, triple-negative (TNBC) in 50/202 (24.8%) and Her2/neu positive in 62/202 (30.7%) patients. Modified radical mastectomy was performed in 88.1% of patients, with 8.5% remaining inoperable and 3.4% declining surgery due to clinical complete response (cCR). Among the patients who underwent MRM, 65/178 (32.2%) patients had a pCR. pCR was observed in 13/81 (16%) with HR-positive disease, 21/46 (45.6%) with TNBC, and 31/51 (60.7%) patients with Her2/neu-positive disease. Grade 3 skin reactions were observed in 39/202 (19.3%). Postoperative wound morbidity requiring hospitalization was observed in 19/178 (10.6%) patients. The median follow-up was 42 months, with 4-year EFS and OS of 63.8% and 71.5%, respectively. Six out of 7 patients who were in cCR and declined surgery are alive and remain in cCR. On subgroup analysis of Her 2 positive patients, pCR was significantly associated with improved EFS and OS (89.8% vs 33.3%, p = 0.001 and 89.1% vs 44.4%, p = 0.001 respectively). Our study demonstrates the feasibility and efficacy of NACCRT in improving operability, pCR rates and survival outcomes in patients with inoperable LABC. The results suggest that NACCRT can be considered for use in clinical practice with careful patient selection. These findings contribute to the ongoing efforts to optimize treatment for this patient population and warrant further investigation in larger, randomized trials.