Impact of Co3O4 nanoparticles on epoxy's mechanical and corrosion-resistance properties for carbon steel in seawater.

Co3O4 nanoparticles (Co3O4-NPs) are synthesized using the facile solvothermal method. FT-IR and XRD spectroscopic analyses verify the creation of cobalt oxide nanoparticles with an average size of 13.20 nm. Furthermore, Zeta potential assessments were carried out to identify the electrical charge of the surface of the produced Co3O4-NPs, which was found to be -20.5 mV.  In addition, the average pore size of Co3O4-NPs is 19.8 nm, and their BET surface area is 92.4 m/g. The study also concerned the effect of Co3O4-NPs on epoxy's improvement of mechanical and corrosion protection for carbon steel in salt solution. By including Co3O4-NPs in an epoxy (EP) coating, corrosion is effectively prevented by non-permeable protective coatings that effectively reduce the transfer of corrosion ions and oxygen.

Cancer Research Challenges and Potential Solutions in Saudi Arabia: A Qualitative Discussion Group Study.

PURPOSE: Cancer incidence in Saudi Arabia has recently shown an upward trend. Research efforts within the different cancer continuum are pivotal to strengthening control measures. Since cancer research is evolving in the country, it is crucial to understand the current challenges and implement defined interventions to overcome them. The present qualitative study aimed to assess cancer research barriers among researchers and identify potential solutions from their perspectives. METHODS: We conducted a focus group discussion among 17 Saudi-based cancer researchers from diverse research backgrounds, provinces, and institutions. We used descriptive-interpretive thematic analysis following an open-ended approach to investigate the challenges in conducting cancer research. We also captured the solutions suggested based on the researchers' experiences. RESULTS: Six major themes emerged from the analysis: requirements of the data landscape, organizational support, national research roadmap, sustainable funding, clearer policies and regulations, and capacity building. To address challenges in these areas, researchers stressed the need for improved interinstitutional collaborations, immediate availability of research materials, and unlimited and easy access to research data. CONCLUSION: Improving health research is one of the primary goals of Saudi Vision 2030. It is, therefore, essential to overcome the current challenges in cancer research, enabling research findings to inform policies related to cancer control and care provision.

Impact of some inorganic anions on the corrosion of nickel in a solution containing Na2SO4 and NaClO4.

Potentiodynamic study was carried out on nickel in Na2SO4 solution in the presence of ClO4-, WO42-, MoO42-, NO2- and NO3- ions. The anodic excursion spans of the metal nickel in a solution of Na2SO4 are marked by the appearance of clearly defined anodic peak, passive region, and transpassive shoulder. According to the data, the anodic peak current density (IPAI) rise from 1.82 to 8.12 mA cm-2 as the concentration of the Na2SO4 solution rises from 0.2 to 1.0 M. It is clear that as scan rate increases, the IPAI rises reaching to 11.8 mA cm-2. The apparent activation energy of nickel corrosion in Na2SO4 is 33.25 kJ mol-1. ClO4- anion addition speeds up nickel's active dissolution, as well tends to break down the passive layer, and causes pitting penetration. It was found that, the pitting potential (Epit) of nickel in solutions containing the two anions ClO4- and SO42- shifts to the positive direction by addition of WO42-, MoO42-, NO2- anions and shifts to the negative direction by addition NO3- anion. Epit increased by 0.67, 0.37 and 0.15 V in the presence of WO42-, MoO42- and NO2-, respectively. WO42- > MoO42- > NO2- was the order in which the inhibitors were most effective.

The Evolving Role of Stereotactic Body Radiation Therapy for Head and Neck Cancer: Where Do We Stand?

Stereotactic body radiation therapy (SBRT) is a precise and conformal radiation therapy (RT) that aims to deliver a high dose of radiation to the tumor whilst sparing surrounding normal tissue, making it an attractive option for head and neck cancer (HNC) patients who are not suitable for the traditional long course of RT with comprehensive RT target volume. Definitive SBRT for HNC has been investigated in different settings, including early stage glottis cancer, and as an alternative to brachytherapy boost after external beam RT. It is also used as a primary treatment option for elderly or medically unfit patients. More recently, an SBRT combination with immunotherapy in the neoadjuvant setting for HNC showed promising results. Salvage or adjuvant SBRT for HNC can be used in appropriately selected cases. Future studies are warranted to determine the optimum dose and fractionation schedules in any of these indications.

A Single-Center Study of the Utility of Bronchoalveolar Lavage in Critically Ill Patients With Haematological Malignancy or Stem Cell Transplants.

INTRODUCTION: The aim of this study was to evaluate the yield of bronchoscopy-guided bronchoalveolar lavage (BAL) and decisions on management of antimicrobials in critically ill patients with hematological malignancy and/or hematological stem cell transplant (HSCT). The safety and tolerance of bronchoscopy were also reported. METHODS: A retrospective cohort study was conducted by reviewing health charts of all adult patients with a hematological malignancy and/or an HSCT who were admitted to the intensive care unit and underwent bronchoscopy and BAL over four years from April 2016 to April 2020 at King Abdulaziz Medical City, Riyadh.  Results: The cohort included 75 critically ill patients. Of these 75 patients, 53 (70.7%) had HSCT (allogenic 66%, autologous 32.1%, haplogenic 3.8%). Computed tomography of the chest was abnormal in all patients. Predominant findings included airspace abnormalities, ground glass opacities, and others. The positive yield was found to be 20% for bacterial, 22% for viral, 21% for fungal, and other organisms were identified in 2%. Although cytology was not performed in 18 patients, malignant cells were identified on BAL in two patients. While the overall mortality of the cohort was high (46.7%), the vast majority (94.7%) tolerated bronchoscopy and BAL without any complications. However, three patients (4%) developed a pneumothorax and one patient bled and developed the acute respiratory distress syndrome post bronchoscopy. CONCLUSIONS: BAL can identify and detect microorganisms directly influencing the clinical care of patients who have received non-invasive diagnostic tests that yielded negative culture results. Bronchoscopy and BAL are generally safe and well tolerated by critically ill patients with hematological malignancy or HSCT.

A Giant Porencephaly: A Rare Etiology of Pediatric Seizures.

Pediatric convulsive seizure is common and represents a source of major concern and anxiety for the parents. Seizures can have a broad spectrum of etiologies in children, including metabolic, traumatic, developmental, and infectious causes. Depending on the clinical presentation, laboratory testing and neuroimaging may be indicated in the workup of the first unprovoked afebrile seizure. We present a case of a six-year-old boy who was brought to the emergency department by his mother after an episode of convulsion. She reported that he had jerky repetitive movements of all extremities that lasted around two minutes with spontaneous termination. The child did not have a febrile illness. The mother reported no history of similar episodes. Upon examination, the child appeared alert and conscious. No dysmorphic features were evident. Initial laboratory investigations were within the normal limits. The child underwent magnetic resonance imaging for the brain, which demonstrated a large well-defined extra-axial cystic lesion occupying most of the left hemisphere that is connected to the ventricular system. The lesion had no grey-matter lining and it strictly followed the cerebrospinal fluid in all sequences. Such finding represented the diagnosis of a giant left porencephalic cyst. Porencephaly is an extremely rare neurological anomaly that may present with pediatric seizures. Magnetic resonance imaging is the gold standard modality for the diagnosis of porencephaly. The case demonstrated that porencephaly can have a massive size in a patient with normal psychoneurological development.

Local delivery to malignant brain tumors: potential biomaterial-based therapeutic/adjuvant strategies.

Glioblastoma (GBM) is the most aggressive malignant brain tumor and is associated with a very poor prognosis. The standard treatment for newly diagnosed patients involves total tumor surgical resection (if possible), plus irradiation and adjuvant chemotherapy. Despite treatment, the prognosis is still poor, and the tumor often recurs within two centimeters of the original tumor. A promising approach to improving the efficacy of GBM therapeutics is to utilize biomaterials to deliver them locally at the tumor site. Local delivery to GBM offers several advantages over systemic administration, such as bypassing the blood-brain barrier and increasing the bioavailability of the therapeutic at the tumor site without causing systemic toxicity. Local delivery may also combat tumor recurrence by maintaining sufficient drug concentrations at and surrounding the original tumor area. Herein, we critically appraised the literature on local delivery systems based within the following categories: polymer-based implantable devices, polymeric injectable systems, and hydrogel drug delivery systems. We also discussed the negative effect of hypoxia on treatment strategies and how one might utilize local implantation of oxygen-generating biomaterials as an adjuvant to enhance current therapeutic strategies.

A retrospective evaluation of the value of COVID-19 screening and testing in patients with cancer: Aiming at a moving target.

BACKGROUND: Diagnosis of COVID-19 infection in cancer patients is critical to co-manage their underlying disease and infection appropriately. Our study aimed at evaluating the sensitivity and specificity of screening patients with cancer for COVID-19 infection. METHODS: All oncology patients receiving care at Department of Oncology at King Abdulaziz Medical City in Riyadh were screened using the acute respiratory infection (ARI) survey. Nasopharyngeal and throat swap for polymerase chain reaction (PCR) testing for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was performed on patients who have high ARI score (i.e. ≥ 4), or any patient requiring elective/emergency hospitalization, undergoing a procedure as well as screening asymptomatic patients receiving chemotherapy between April 1st and July 30, 2020. Institutional Review Board approval was obtained. Descriptive and inferential analyses were done and sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated considering the COVID-19 PCR as the gold standard. RESULTS: During the study period, a total of 473 patients were included with a median age was 56 years (14-104), 51% were female, 73% had solid tumors, and 66% received treatment within the last 3 months. These patients underwent 688 PCR tests along with ARI survey screening. Testing was done in the outpatient, inpatient, and emergency department setting in 41%, 40% and 19% of the patients, respectively. Majority of tests were screening of asymptomatic patients and only 23% were tested for suspected infections with ARI ≥ 4. A total of 54 patients (8%) had positive PCR for COVID-19 infection. The prevalence of infection varied from month to month ranging from 1.09% in April up to 19.70% in June and correlated with the average daily and active case load at a national level. The diagnostic yield of the ARI score also correlated with infection burden nationally. The PPV and NPV of the ARI as a screening tool was 18.24% (0-31.8) and 95.6% (86.36-98.86%) with the PPN fluctuating considerably in parallel with the prevalence of COVID-19 result. Similarly, the sensitivity and specificity of the ARI were 55.77% (0-70.59) and 79.4 (69.19-92), respectively. CONCLUSION: The yield of screening asymptomatic patients with cancer varies based on the community burden of COVID-19 infection. As universal screening can cause delays to patient care, it should be tailored based on the individual patient risks and infection burden in the region.

Scholarly Activity of Radiation Oncologists in High-Income Developing Countries: Saudi Arabia as an Example.

PURPOSE: To examine the trends and quality metrics of publications by radiation oncologists in Saudi Arabia. METHODS: PubMed was searched using names of all Saudi radiation oncologists to retrieve published articles between January 2010 and December 2019. International collaboration, journal impact factor and country of origin, and number of citations were collected. Each article was assessed for epidemiologic type and independently assigned a level of evidence (LOE) by two authors. The trend in publications was examined and compared in the first and second 5-year periods (2010-2014 and 2015-2019) using relevant parameters. RESULTS: A total of 186 publications were found and included. The most common type of research was cohort studies followed by case reports and case series in 24%, 14%, and 13% of all publications, respectively. Dosimetry, clinical, and preclinical studies formed 7%, 8.6%, and 7.5% of the total publications, respectively. The LOE was I, II, III, IV, and not applicable in 8.6%, 22%, 25.8%, 29%, and 14.5% of the included publications, respectively. Comparing the first and second 5-year periods, there was an increase in international collaboration (P < .001) in the second period. The number of citations (P < .001) and journal impact factor (P = .028) were lower in the second period. LOE and publications in international journals were not statistically different between the two periods. CONCLUSION: Although radiation oncology research activity in Saudi Arabia has gained momentum in terms of volume and international collaboration over time, the LOE has not improved. This calls for a national effort to make the contribution to the literature a priority, allocate adequate resources, and apply appropriate measures to enhance research productivity and quality.

Management guidelines for stage III non-small cell lung cancer.

Management of stage III non- small cell lung cancer (NSCLC) is very challenging due to being a group of widely heterogeneous diseases that require multidisciplinary approaches with timely and coordinated care. The standards of care had significant changes over the last couple of years because of the introduction of consolidation therapy with checkpoint inhibitor following concurrent chemo-radiotherapy and the evolving new role of tyrosine kinase inhibitors in the adjuvant setting. The manuscript presents evidence-based recommendations for the workup, staging, treatment and follow up of the various subtypes of stage III NSCLC. The guidelines were developed by experts in various fields of thoracic oncology and guidelines development. The guidelines consider the sequence of interventions and the role of each discipline in the management of the disease taking into account the recent development and included required resources to help physicians provide better care.

Contribution of Pathologists in Leading Clinical Cancer Research Through Interdisciplinary Collaboration in Saudi Arabia.

Background Interdisciplinary collaboration is often the key to advance cancer research. This research collaboration is frequently observed between oncologists and pathologists. While clinical cancer research is often led by oncologists, the leading role of pathologists is likely limited to laboratory-based and preclinical research. Therefore, the magnitude and characteristics of clinical studies led by pathologists is largely unknown. Objectives The objective of our study was to assess the quantity and quality of clinical cancer-related publications led by Saudi pathologists over a 10-year period. Methods A PubMed search was conducted between January 2008 and December 2017 to extract all published clinical articles regarding cancer by at least one Saudi pathologist with the collaboration of other cancer specialists. Information about articles and authors were collected. The level of evidence (LOE) was independently assessed by two authors. Two five-year periods (2008 - 2012 and 2013 - 2017) were compared using the relevant parameters. Results A total of 127 publications met our inclusion criteria and were included. Review articles (27%) were the most common type of publication. There were no experimental studies. The LOE was III and IV in 59.1% and 40.9% of the included publications, respectively. Comparing the two five-year periods, the number of publications (p < 0.001), publications in international journals (p = 0.004), and international collaborations (p < 0.001) increased in the second period. The LOE and journal impact factor were the same in the two periods. Conclusions The pathologist-led clinical cancer research in Saudi Arabia increased over time. Despite the observed increase in international collaboration and publications in international journals, the LOE was low (III/IV) and did not change over time.

Locally Advanced Oral Cavity Cancers: What Is The Optimal Care?

Patients with oral cavity cancers often present late to seek medical care. Surgery is usually the preferred upfront treatment. However, surgical resection cannot be achieved in many cases with advanced disease without major impact on patient's quality of life. On the other hand, radiotherapy (RT) and chemotherapy (CT) have not been employed routinely to replace surgery as curative treatment or to facilitate surgery as neoadjuvant therapy. The optimal care of these patients is challenging when surgical treatment is not feasible. In this review, we aimed to summarize the best available evidence-based treatment approaches for patients with locally advanced oral cavity cancer. Surgery followed by RT with or without CT is the standard of care for locally advanced oral cavity squamous cell carcinoma. In the case of unresectable disease, induction CT prior to surgery or chemoradiotherapy (CRT) can be attempted with curative intent. For inoperable patients or when surgery is expected to result in poor functional outcome, patients may be candidates for possibly curative CRT or palliative RT with a focus on quality of life.

Oncology research in Saudi Arabia over a 10-year period. A synopsis.

OBJECTIVES: To assess the quality and quantity of Saudi publications in oncology over a 10-year period. METHODS: A systematic PubMed search was conducted between January 2008 and December 2017 to retrieve all Saudi oncology publications. Data about the articles was collected. The level of evidence (LOE) was independently assessed by 2 authors. Two 5-year periods (2008-2012 and 2013-2017) were compared using the relevant parameters. Clinicaltrials.gov was also searched for all oncology trials registered in Saudi Arabia. RESULTS: A total of 839 publications met our inclusion criteria. The most common type of research was case series, totaling 32% of all publications. Clinical trials formed less than 2% of the total. The LOE was I, II, III, and IV in 0.3%, 2.1%, 58.4%, and 39.3% of the included publications, respectively. The LOE was the same in the 2 periods. There were more publications in international journals (p=0.004), more international collaborations (p=0.001), and higher journal impact factors (p=0.037) in 2013-2017 than in 2008-2012. Only 76 registered clinical trials were found in the Clinicaltrials.gov registry. CONCLUSION: Despite an increase in the number of Saudi publications in the field of oncology over time, the LOE did not change. There were, however, some improvements in the international collaboration and journal impact factor, as well as an increase in the number of studies published in international journals. These observations call for a national strategy to improve oncology research in Saudi Arabia.

Highlights on the Management of Oligometastatic Disease.

Purpose: The understanding of oligometastatic disease (OMD) is rapidly evolving and with this comes the ability to utilize a number of modalities that excel in the localized control of disease. It has been identified that there are no clear guidelines based on high-level evidence to standardized approaches toward the management of OMD. These highlights have been developed to provide a road map for all health-care professionals who are involved in the management of OMD to support standardized patient care. Methods: The Saudi Lung Cancer Guidelines Committee is a part of the Saudi Lung Cancer Association which, in turn, is part of the Saudi Thoracic Society. Considering that lung cancer constitutes a major proportion of OMD prevalence, the committee took the initiative to develop national highlights to support the management of OMD within Saudi Arabia. The committee members are national clinical leaders who collaborated with international expertise to establish these highlights to serve as a general clinical pathway in the management of OMD. Results: Standardization of the indications to diagnose oligometastases and patient selection criteria including ineligibility criteria for treatment are the basis of the highlights. Treatment approaches including surgical and the variety of radiotherapeutical options are discussed in relation to specific oligometastatic sites. Acceptable measurements for response to treatment and the future for the treatment of OMD conclude the development of the highlights. Conclusion: These are the first national highlights addressing this important disease in oncology. The implementation of these highlights as guidelines requires a robust multidisciplinary team and access to specific technology and expertise. These highlights are based on the most recent findings within the literature but will require repeated review and updating due to this rapidly evolving field in disease management.

Poly(ethylene glycol) based nanotubes for tuneable drug delivery to glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the most aggressive type of malignant brain tumour, which is associated with a poor two-year survival rate and a high rate of fatal recurrence near the original tumour. Focal/local drug delivery devices hold promise for improving therapeutic outcomes for GBM by increasing drug concentrations locally at the tumour site, or by facilitating the use of potent anti-cancer drugs that are poorly permeable across the blood brain barrier (BBB). For inoperable tumours, stereotactic delivery to the tumour necessitates the development of nanoscale/microscale injectable drug delivery devices. Herein we assess the ability of a novel class of polymer nanotube (based on poly(ethylene glycol) (PEG)) to load doxorubicin (a mainstay breast cancer therapeutic with poor BBB permeability) and release it slowly. The drug loading properties of the PEG nanotubes could be tuned by varying the degree of carboxylic acid functionalisation and hence the capacity of the nanotubes to electrostatically bind and load doxorubicin. 70% of the drug was released over the first seven days followed by sustained drug release for the remaining two weeks tested. Unloaded PEG nanotubes showed no toxicity to any of the cell types analysed, whereas doxorubicin loaded nanotubes decreased GBM cell viability (C6, U-87 and U-251) in a dose dependent manner in 2D in vitro culture. Finally, doxorubicin loaded PEG nanotubes significantly reduced the viability of in vitro 3D GBM models whilst unloaded nanotubes showed no cytotoxicity. Taken together, these findings show that polymer nanotubes could be used to deliver alternative anti-cancer drugs for local therapeutic strategies against brain cancers.

Postoperative Stereotactic Body Radiotherapy for Spinal Metastases and the Impact of Epidural Disease Grade.

BACKGROUND: Postoperative stereotactic body radiotherapy (pSBRT) is an emerging indication for spinal metastases (SM). OBJECTIVE: To report our experience with pSBRT for SM. METHODS: A retrospective chart review was performed for prospectively collected data of patients treated between September 2008 to December 2015 with pSBRT and followed with serial spinal MRIs every 2 to 3 mo until death or last follow-up. Univariate and multivariable analyses were performed to identify predictive factors. RESULTS: A total of 83 spinal segments in 47 patients treated with a median dose of 24 Gy in 2 fractions were included, with mostly lung and breast primaries. A total of 59.3% had preoperative high-grade epidural disease (ED) and 39.7% were unstable. The 12-mo cumulative incidence of local failure was 17% for all segments, and 33.3%, 21.8%, and 0% in segments with postoperative high-grade, low-grade, and no ED, respectively. Downgrading preoperative ED was predictive of better local control (P = .03). The grade of postoperative ED was also predictive for local control (P < .0001), as was a longer interval between prior radiotherapy and pSBRT in those previously irradiated (P = .004). The 12-mo overall survival rate was 55%. One case of radiculopathy, 3 vertebral compression fractures, and no cases of myelopathy, hardware failure, or skin breakdown were observed. CONCLUSION: pSBRT is an effective and safe treatment. The association between downgrading preoperative ED and better local control following pSBRT is confirmed and supports the concept of separation surgery.

Survey of flexible bronchoscopy practice in adults in Saudi Arabia.

OBJECTIVES: To assess current adherence to international guidelines for practitioners of bronchoscopy in the Kingdom of Saudi Arabia. Methods: A cross-sectional survey was conducted in Saudi Arabia between December 2016 and March 2017. Pulmonologists, thoracic surgeons, and intensivists were invited to answer an emailed self-administered questionnaire survey seeking information on how they performed flexible bronchoscopy in adults. The data collected were compared between the 3 specialties. Results: Eighty-two (18%) of 456 invited practitioners completed the survey. Fifty-eight (72%) of the 82 respondents were pulmonologists. Forty (53%) of 76 respondents (93%) who had received bronchoscopy training received it abroad. Twenty-seven respondents (33%) had also received training in endobronchial ultrasound, electrocautery, brachytherapy, stent insertion, and laser procedures. Fifty-eight respondents (70%) preferred patients to undergo fasting for at least 4 hours before the procedure. Lidocaine was used for topical anesthesia, mainly by aerosol spray or nebulization. Midazolam was used by 62%, fentanyl by 50%, and propofol by 12% of respondents. Ninety percent of pulmonologists reported requesting a chest radiograph after transbronchial lung biopsy. Safety procedures for bronchoscopists, for example, wearing masks and eye protection, and for patients, for example, availability of anesthetic reversal agents, were not universally applied. Conclusion: Bronchoscopy is not standardized in Saudi Arabia. National guidelines for the indications and practice of bronchoscopy are required.

Saudi lung cancer prevention and screening guidelines.

BACKGROUND: While lung cancer is the leading cancer cause of death, it is largely preventable. Furthermore, early diagnosis enhances the chance of cure. Therefore, we developed guidelines for lung cancer prevention and early detection. METHODS: A multidisciplinary team of experts in lung cancer representing different health-care sectors was assembled based on the National Cancer Center request and in coordination with the Saudi Lung Cancer Association of Saudi Thoracic Society. The team reviewed various reliable international guidelines and the data and experience in the Kingdom and formulated guidelines that address the primary and secondary prevention approaches in lung cancer, including tobacco control, early diagnosis, and lung cancer screening. RESULTS: The team developed guidelines to assist healthcare professionals in the Kingdom manage the different aspects of lung cancer prevention. Primary prevention through tobacco control: the recommendations encourage all healthcare professionals in all practice settings to screen their patients for smoking and to provide counseling and if needed referral to smoking cessation programs for current smokers. For early diagnosis of patients with symptoms suspicions of lung cancer, it is expected standard of care to investigate, work up, and refer the patients appropriately. Mass screening of patients at high risk for developing lung cancer: the recommendations listed the program requirements, eligible patients, and algorithm to manage findings. However, the team does not recommend that national screening program be mandated or implemented for lung cancer at this stage until more data and studies provide stronger evidence to justify adopting a national program. CONCLUSIONS: Physicians can play an important role in preventing lung cancer by tobacco control and also detect lung cancer at earlier presentation. However, national mass screening programs require further study.

Stereotactic radiosurgery for resected brain metastasis: Cavity dynamics and factors affecting its evolution.

OBJECTIVE: To determine changes in post-surgical cavity volume for metastases based on time from surgery, pre-operative tumor dimensions and other predictors, in patients planned for post-operative stereotactic radiosurgery (SRS). METHODS: Patients with resected brain metastases from a primary solid tumor, treated with post-operative surgical cavity SRS from 2008 to 2014 were identified from an institutional prospective database. The segmented three-dimensional (3D) volume of the pre-operative tumor and post-operative surgical cavity were determined based on MRI and percent volume change was calculated. Patients were grouped according to early (<21 days), intermediate (22-42 days), and late (>42 days) intervals based on the number of days between the date of surgery and the treatment planning MRI. Potential predictive factors including tumor size, location, age, dural involvement, and degree of surgical resection were also analyzed. RESULTS: Sixty-one cavities in 59 patients were evaluated. Overall, a significant volume reduction (4cm3, p=0.03) was observed comparing tumor and cavity volumes. For larger tumors, an average volume reduction of 11.6% (p=0.01) was observed compared to an increase of 34.4% in smaller tumors (p=0.69). For both large and small tumors, cavities were larger in the early interval especially for smaller tumors. During the intermediate interval, a significant volume reduction was observed for larger tumors (28%, p=0.0007). Tumor size, dural involvement, age and time from surgery were significant predictors for volume change on univariate analysis. On multivariate analysis, tumor size, dural involvement and time from surgery were significant. CONCLUSION: Tumor size (>3cm), dural involvement and longer time from surgery were significant predictors of cavity volume reduction. Caution must be taken when treating cavities in the early (<21 days) interval after surgery as it may lead to irradiating more normal tissue especially in small tumors.

Clinical implementation of AXB from AAA for breast: Plan quality and subvolume analysis.

PURPOSE: Two dose calculation algorithms are available in Varian Eclipse software: Anisotropic Analytical Algorithm (AAA) and Acuros External Beam (AXB). Many Varian Eclipse-based centers have access to AXB; however, a thorough understanding of how it will affect plan characteristics and, subsequently, clinical practice is necessary prior to implementation. We characterized the difference in breast plan quality between AXB and AAA for dissemination to clinicians during implementation. METHODS: Locoregional irradiation plans were created with AAA for 30 breast cancer patients with a prescription dose of 50 Gy to the breast and 45 Gy to the regional node, in 25 fractions. The internal mammary chain (IMCCTV ) nodes were covered by 80% of the breast dose. AXB, both dose-to-water and dose-to-medium reporting, was used to recalculate plans while maintaining constant monitor units. Target coverage and organ-at-risk doses were compared between the two algorithms using dose-volume parameters. An analysis to assess location-specific changes was performed by dividing the breast into nine subvolumes in the superior-inferior and left-right directions. RESULTS: There were minimal differences found between the AXB and AAA calculated plans. The median difference between AXB and AAA for breastCTV V95% , was <2.5%. For IMCCTV , the median differences V95% , and V80% were <5% and 0%, respectively; indicating IMCCTV coverage only decreased when marginally covered. Mean superficial dose increased by a median of 3.2 Gy. In the subvolume analysis, the medial subvolumes were "hotter" when recalculated with AXB and the lateral subvolumes "cooler" with AXB; however, all differences were within 2 Gy. CONCLUSION: We observed minimal difference in magnitude and spatial distribution of dose when comparing the two algorithms. The largest observable differences occurred in superficial dose regions. Therefore, clinical implementation of AXB from AAA for breast radiotherapy is not expected to result in changes in clinical practice for prescribing or planning breast radiotherapy.