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BACKGROUND AND PURPOSE: Regional nodal irradiation (RNI) is commonly administered in patients with breast cancer with node-positive disease to prevent cancer recurrence. The purpose of this study is to identify whether RNI is associated with greater acute symptom burden from baseline to 1 to 3 months post completion of radiotherapy (RT) when compared to localized RT. MATERIALS AND METHODS: Patient and treatment characteristics were collected prospectively for breast cancer patients with and without RNI from February 2018 to September 2020. The Edmonton Symptom Assessment System (ESAS) and Patient-Reported Functional Status (PRFS) tool were completed by patients at baseline, weekly during RT, and at a 1- to 3-month follow-up visit. The Wilcoxon rank-sum or Fisher exact tests were used to compare variables between patients with or without RNI. RESULTS: A total of 781 patients were included in the analysis. Baseline symptom reporting was similar between cohorts, with the exception of PRFS scores (p = 0.0023), which were worse in patients receiving RNI. Across all time points, differences in outcomes between cohorts were minimal, except for lack of appetite (p = 0.03) and PRFS scores (p = 0.049), which were significantly aggravated in patients treated with RNI. CONCLUSION: There is insufficient evidence to suggest that RNI is associated with greater symptom burden as assessed with the ESAS. Further research should be conducted over a longer time period to determine the impact of late effects of RNI on patient-reported symptoms.
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Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/radioterapia , Recidiva Local de Neoplasia , Medidas de Resultados Relatados pelo PacienteRESUMO
INTRODUCTION: Self-administered methoxyflurane, also known as Penthrox, at a sub-anesthetic dose is a short-term, fast-acting, and safe analgesic that may provide suitable pain relief for cancer patients. This review aims to compile the existing evidence on methoxyflurane and its efficacy in reducing pain during cancer-related procedures. METHODS: A literature search was conducted through OVID Medline and Embase. The search was limited to articles published between 2012 and 2021 and studies were included if they assessed the efficacy of methoxyflurane to reduce pain in cancer-related procedures. All types of cancer were included. RESULTS: The literature search yielded seven studies published between 2012 and 2021. The studies analyzed assessed methoxyflurane use in prostate biopsy, colonoscopy, removal of brachytherapy rods, and bone marrow biopsy. Various research designs were employed, including three randomized controlled trials, two prospective observational studies, one retrospective, and one non-randomized controlled trial. In all, methoxyflurane has a demonstrated ability to reduce pain in these procedures. CONCLUSION: In the limited studies available in evaluating the efficacy of methoxyflurane for reducing procedural pain during cancer-related procedures, all have demonstrated clinical equivalency or superiority. Pain relief appears to be equivalent however methoxyflurane overcomes the standard limitations of respiratory sedation and has demonstrated quicker procedural recovery times than traditional sedation methods. The accumulated data to date supports the use of methoxyflurane which can supplement or supplant current methods of analgesia in cancer-related procedures.
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Anestésicos Inalatórios , Dor do Câncer , Neoplasias , Humanos , Masculino , Anestésicos Inalatórios/uso terapêutico , Dor do Câncer/tratamento farmacológico , Dor do Câncer/etiologia , Metoxiflurano/uso terapêutico , Neoplasias/complicações , Neoplasias/tratamento farmacológico , Estudos Observacionais como Assunto , Dor/tratamento farmacológico , Dor/etiologia , Estudos Retrospectivos , Ensaios Clínicos Controlados como AssuntoRESUMO
BACKGROUND AND PURPOSE: Patients undergoing radiotherapy (RT) for breast cancer may receive adjuvant or neoadjuvant chemotherapy prior to the initiation of RT treatment. In the present study, baseline Edmonton Symptom Assessment System (ESAS) scores of patients who received neoadjuvant and adjuvant chemotherapy were collected prior to RT and compared to assess the association of each chemotherapy intent with pre-RT symptom burden. MATERIAL AND METHODS: The ESAS and Patient-Reported Functional Status (PRFS) tools were used to collect patient-reported symptoms at baseline. Patient and treatment-related factors were collected prospectively from February 2018 to September 2020. Univariate general linear regression analysis was applied to compare baseline scores between adjuvant and neoadjuvant chemotherapy patients. RESULTS: A total of 338 patients were included for analysis. Comparison of baseline ESAS scores revealed that patients who received adjuvant chemotherapy were more likely to report higher scores, reflecting higher symptom burden, compared to patients receiving neoadjuvant chemotherapy, including tiredness (p = 0.005), lack of appetite (p = 0.0005), shortness of breath (p < 0.0001), and PRFS (p = 0.012). CONCLUSION: This study suggests an association between patients who have received adjuvant chemotherapy for breast cancer and higher RT baseline ESAS scores when compared to patients who received neoadjuvant chemotherapy. Due to these findings, considerations should be made by healthcare providers of the symptom burden during RT for patients who receive adjuvant chemotherapy.
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Neoplasias da Mama , Radioterapia (Especialidade) , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/diagnóstico , Terapia Neoadjuvante , Avaliação de Sintomas , Quimioterapia AdjuvanteRESUMO
PURPOSE: The Edmonton Symptom Assessment Scale (ESAS) is a validated tool used in patients with varied cancer diagnoses to measure patient symptoms. The present manuscript will review the literature assessing the ability of the ESAS to predict patient-related outcomes in breast cancer patients. METHODS: A literature search was conducted of Cochrane Central Register of Controlled Trials databases, Ovid MEDLINE, and Embase for English articles that investigated the use of predictive modelling with the ESAS in the breast cancer population. Study type, publication year, sample size, patient demographics, predicted outcomes, and strongest predictive factors/symptoms were summarized for each study. RESULTS: A total of nine articles were included in this review. Five articles used the ESAS in predictive models to determine patient time to death. ESAS was also used to predict emergency department visits, determine symptoms associated with decreased quality of life, and generate a Health Utility Score. Lack of appetite was the most common ESAS symptom, as it was reported in five studies to be associated with decreased survival. In four of the nine articles, an additional survey investigating physical functioning was used in combination with ESAS to strengthen the predictive models. CONCLUSIONS: Included studies support the use of ESAS in predictive models, particularly for predicting survival. Using the ESAS as a predictive tool allows for more accurate time to death predictions, potentially improving symptom management and preventing overtreatment of palliative patients near the end of life.
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Neoplasias da Mama/diagnóstico , Neoplasias da Mama/mortalidade , Feminino , Humanos , Modelos Estatísticos , Cuidados Paliativos , Prognóstico , Qualidade de Vida , Inquéritos e Questionários , Avaliação de SintomasRESUMO
PURPOSE: This review aimed to assess the quality and efficacy of tools currently used in breast cancer patients to score radiation dermatitis (RD), a common debilitating side effect of radiotherapy (RT). METHODS: A search was conducted through Ovid Medline, Embase, and Cochrane Central Register of Controlled Trials databases on 14 February 2020. English articles that evaluated an instrument's use in assessing RD among breast cancer patients receiving external beam RT were included. Studies that reported on the reliability, validity, or concordance of items between assessment tools were included in accordance with the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) criteria. RESULTS: Twelve studies were included in this review, with a total of 13 skin toxicity assessment tools discussed. Tools that assessed clinician-reported outcomes (CROs) mostly reported moderate correlation with biophysical parameter (BP) measurements and low correlation with patient-reported outcomes (PROs). Traditionally used CRO scoring tools demonstrated moderate inter-rater reliability between clinicians, likely due to the subjective nature of items on the grading scales. Most commonly used tools were found to be either insufficient or indeterminate in their measurement properties. CONCLUSIONS: Current standardized tools that measure CROs are subject to clinician interpretation and fail to represent the patient experience. Tools designed to assess PROs are promising in their assessments of the impact of RT on patient quality of life; however, most PRO tools are generic to all skin conditions and require further validation for use in breast cancer. Among tools that measure CROs, PROs, and BPs, there is insufficient evidence on their measurement properties to establish a "gold standard" for the assessment of RD in breast cancer patients.
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Neoplasias da Mama/complicações , Radiodermite/etiologia , Feminino , Humanos , Pessoa de Meia-Idade , Radiodermite/fisiopatologia , Reprodutibilidade dos TestesRESUMO
Posttraumatic stress disorder (PTSD) is a trauma and stressor-related disorder that is characterized by dysregulation of glucocorticoid signaling, chronic low-grade inflammation, and impairment in the ability to extinguish learned fear. Corticotropin-releasing hormone (Crh) is a stress- and immune-responsive neuropeptide secreted from the paraventricular nucleus of the hypothalamus (PVN) to stimulate the hypothalamic-pituitary-adrenal (HPA) axis; however, extra-hypothalamic sources of Crh from the central nucleus of the amygdala (CeA) and bed nucleus of the stria terminalis (BNST) govern specific fear- and anxiety-related defensive behavioral responses. We previously reported that preimmunization with a heat-killed preparation of the immunoregulatory environmental bacterium Mycobacterium vaccae NCTC 11659 enhances fear extinction in a fear-potentiated startle (FPS) paradigm. In this follow-up study, we utilized an in situ hybridization histochemistry technique to investigate Crh, Crhr1, and Crhr2 mRNA expression in the CeA, BNST, and PVN of the same rats from the original study [Fox et al., 2017, Brain, Behavior, and Immunity, 66: 70-84]. Here, we demonstrate that preimmunization with M. vaccae NCTC 11659 decreases Crh mRNA expression in the CeA and BNST of rats exposed to the FPS paradigm, and, further, that Crh mRNA expression in these regions is correlated with fear behavior during extinction training. These data are consistent with the hypothesis that M. vaccae promotes stress-resilience by attenuating Crh production in fear- and anxiety-related circuits. These data suggest that immunization with M. vaccae may be an effective strategy for prevention of fear- and anxiety-related disorders.
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Hormônio Liberador da Corticotropina/efeitos dos fármacos , Medo/efeitos dos fármacos , Mycobacteriaceae/imunologia , Tonsila do Cerebelo/efeitos dos fármacos , Tonsila do Cerebelo/metabolismo , Animais , Ansiedade/fisiopatologia , Ansiedade/terapia , Encéfalo/metabolismo , Hormônio Liberador da Corticotropina/metabolismo , Medo/fisiologia , Seguimentos , Expressão Gênica/efeitos dos fármacos , Sistema Hipotálamo-Hipofisário/metabolismo , Imunização/métodos , Masculino , Neuropeptídeos/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Sistema Hipófise-Suprarrenal/metabolismo , Ratos , Ratos Sprague-Dawley , Reflexo de Sobressalto/efeitos dos fármacos , Reflexo de Sobressalto/fisiologia , Núcleos SeptaisRESUMO
BACKGROUND AND PURPOSE: As breast cancer radiotherapy (RT) has been shown to give rise to adverse pulmonary outcomes, such as radiation pneumonitis, trends in patient-reported shortness of breath (SOB) associated with RT were investigated. Adjuvant RT is commonly administered for local and/or regional control of breast cancer and was therefore included. METHODS: The Edmonton Symptom Assessment System (ESAS) was used to observe changes in SOB during RT, up to 6 weeks after RT completion, and one to three months post-RT. Patients with at least one completed ESAS were included in the analysis. Generalized linear regression analysis was performed to identify associations between demographic factors and SOB. RESULTS: A total of 781 patients were included in the analysis. There was a significant association between ESAS SOB scores and adjuvant chemotherapy when compared to neoadjuvant chemotherapy (p=0.0012). Meanwhile, loco-regional RT had no significant impact on ESAS SOB scores in comparison to local RT. SOB scores were stable over time (p>0.05) from baseline to follow-up appointments. CONCLUSION: The findings of this study suggest that RT was not associated with changes in SOB from baseline to 3 months post-RT. However, patients who underwent adjuvant chemotherapy reported significant higher SOB scores over time. Additional research is recommended to analyze the lasting effects of adjuvant breast cancer RT on SOB during physical activity.
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Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/radioterapia , Neoplasias da Mama/diagnóstico , Radioterapia Adjuvante , Mama , Dispneia/etiologia , Medidas de Resultados Relatados pelo PacienteRESUMO
BACKGROUND: The then-test, also known as the retrospective pre- and post-test design method, is a measurement used to evaluate response shift. The method requires patients to assess their previous health-related quality of life (HRQoL) and provide a retrospective judgement based on their current perspectives. The then-test, however, has been criticized for its reliability and validity. The objective of this systematic review is to summarize the current literature for the use of the then-test for evaluating HRQoL in cancer patients and account for potential response shift effects. METHODS: A literature search was conducted in May 2022 using MEDLINE, PubMed, and PsychINFO dated from 2005 to the time of the search. Studies were included if they (I) used the then-test and (II) involved a population of cancer patients (any cancer site). RESULTS: The literature search resulted in 16 studies, published between 2005 and 2020. All studies used the then-test to detect response shifts. The EORTC QLQ-C30 and EORTC QLQ-BR23 questionnaires were the most common assessments used to evaluate HRQoL. Of the 16 articles, 5 exclusively reported on breast cancer, 5 reported on prostate cancer, and the remaining included all cancer sites. Most studies looked at patients undergoing a combination of chemotherapy, radiotherapy, and hormonal therapy. The mean differences between the retrospective assessment at both 3 and 6 months were significant for various quality of life (QoL) dimensions. Patients in some studies recalled their pretreatment HRQoL (then-score) as better than the pretreatment baseline scores and others reported them as worse, both confirming the existence of a response shift. CONCLUSIONS: Our review demonstrates that the then-test measurement tool has been commonly used for the detection of response shift. Newer measures for response shift have become more accepted; the then-test, if used, should be used with caution considering its limitations and the emergence of more advanced methods.
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Neoplasias da Mama , Qualidade de Vida , Masculino , Humanos , Estudos Retrospectivos , Reprodutibilidade dos Testes , Neoplasias da Mama/tratamento farmacológico , Inquéritos e QuestionáriosRESUMO
PURPOSE: Radiation dermatitis (RD) is common in patients undergoing breast radiotherapy. Mepitel film (MF) can reduce RD, but the results from two randomized controlled trials are conflicting. We aimed to conduct a confirmatory randomized controlled trial in patients at risk of RD. METHODS: Patients were randomly assigned to receive MF or standard care (2:1 ratio). Patients with large breasts after lumpectomy (bra size ≥ 36 inches or cup size ≥ C) or after mastectomy were eligible. Stratification factors included surgery type, dose fractionation, and administration of boost/bolus. The primary end point was grade (G) 2 or 3 RD using the Common Terminology Criteria for Adverse Events v5.0. Secondary end points included patient- and clinician-reported outcomes. RESULTS: Between January 2020 and May 2022, 376 patients were included in the modified intention-to-treat analysis. The incidence of G2 or 3 RD was significantly lower in MF patients compared with standard care (n = 39/251, 15.5%; 95% CI, 11.3 to 20.6% v n = 57/125, 45.6%; 95% CI, 36.7 to 54.8% respectively, odds ratio (OR): 0.20, P < .0001). Benefits of MF remained significant in patients who developed G 3 RD (n = 7, 2.8%; 95% CI, 1.1 to 5.7% v n = 17, 13.6%; 95% CI, 8.1 to 20.9%, OR: 0.19) and moist desquamation (n = 20, 8.0%; 95% CI, 4.9 to 12.0% v n = 24, 19.2%; 95% CI, 12.7 to 27.1%, OR: 0.36). When evaluating the combined patient and health care provider score using Radiation-Induced Skin Reaction Assessment Scale, the MF arm had significantly lower scores (P < .0001). Individual items on the Radiation-Induced Skin Reaction Assessment Scale also favored the MF for both patient- and clinician-reported outcomes. Blistering/peeling, erythema, pigmentation, and edema were significantly reduced in the MF arm. Three patients removed the film prematurely because of rash (n = 2) and excessive pruritus (n = 1). CONCLUSION: MF significantly reduces RD in patients undergoing breast radiotherapy.
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Neoplasias da Mama , Radiodermite , Humanos , Feminino , Neoplasias da Mama/radioterapia , Neoplasias da Mama/cirurgia , Neoplasias da Mama/complicações , Mastectomia/efeitos adversos , Radiodermite/etiologia , Radiodermite/prevenção & controle , Silicones , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
BACKGROUND AND OBJECTIVE: The 30-day expected mortality rate is frequently used as a metric to determine which patients benefit from palliative radiation treatment (RT). We conducted a narrative review to examine whether its use as a metric might be appropriate for patient selection. METHODS: A literature review was conducted to identify relevant studies that highlight the benefits of palliative RT in timely symptom management among patients with a poor performance status, the accuracy of predicting survival near the end of life and ways to speed up the process of RT administration through rapid response clinics. KEY CONTENT AND FINDINGS: Several trials have demonstrated substantial response rates for pain and/or bleeding by four weeks and sometimes within the first two weeks after RT. Models of patient survival have limited accuracy, particularly for predicting whether patients will die within the next 30 days. Dedicated Rapid Access Palliative RT (RAPRT) clinics, in which patients are assessed, simulated and treated on the same day, reduce the number of patient visits to the radiation oncology department and hence the burden on the patient as well as costs. CONCLUSIONS: Single-fraction palliative RT should be offered to eligible patients if they are able to attend treatment and could potentially benefit from symptom palliation, irrespective of predicted life expectancy. We discourage the routine use of the 30-day mortality as the only metric to decide whether to offer RT. More common implementation of RAPRT clinics could result in a significant benefit for patients of all life expectancies, but particularly those having short ones.
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Dor , Cuidados Paliativos , Humanos , Dor/radioterapiaRESUMO
PURPOSE: Radiation dermatitis (RD) is a side effect experienced by many patients undergoing radiotherapy (RT) for breast cancer. In the present study, the Edmonton Symptom Assessment System (ESAS), a validated patient-reported symptom screening tool, was used to determine the impacts of RT-induced skin outcomes on ESAS items. Patient- and treatment-related factors and skin treatments to manage RD symptoms, were assessed for association with ESAS scores. METHODS: Patient and treatment characteristics were collected retrospectively for breast cancer patients treated with adjuvant RT between December 2013 and November 2015. Prospective data was collected through clinician-reported surveys. Linear regression analyses were performed to detect the relationship between patient-reported ESAS scores and clinician-reported RD symptoms. RESULTS: A total of 857 patients were included in the analysis. Moderate to severe scores were commonly reported for fatigue (n = 412, 48%), wellbeing (n = 386, 45%) and anxiety (n = 266, 31%). Oral analgesic use was associated with ESAS fatigue, drowsiness, pain, nausea, lack of appetite, shortness of breath, and wellbeing (P < .05), while dressings were only associated with anxiety (P = .02). No RD symptoms were found to be significantly associated with any ESAS items. CONCLUSIONS: The ESAS accurately reflects symptoms of fatigue, anxiety, and wellbeing for breast cancer patients undergoing RT. Our study, however, found no association between ESAS scores and RD severity, which may reflect the shortcomings of the ESAS in assessing symptom burden. Further research is necessary to warrant the development of a new site-specific symptom screening tool for use in RT for breast cancer.
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Neoplasias da Mama , Radiodermite , Neoplasias da Mama/radioterapia , Fadiga/diagnóstico , Feminino , Humanos , Cuidados Paliativos , Estudos Prospectivos , Qualidade de Vida , Radiodermite/diagnóstico , Radiodermite/etiologia , Estudos RetrospectivosRESUMO
BACKGROUND AND PURPOSE: Breast cancer patients frequently develop radiation dermatitis (RD) when undergoing post-operative radiation therapy (RT). Traditional RD assessment methods measure clinician-reported outcomes (CROs), but patient-reported outcomes (PROs) have gained recent popularity. The purpose of this prospective analysis was to compare PROs with CROs of breast RD. MATERIALS AND METHODS: Demographic and treatment characteristics were prospectively collected for patients receiving post-operative RT between February 2018 to September 2020. Patients and clinicians completed a skin symptom assessment at baseline, weekly during RT, and at a one- to three-month follow-up visit. Skin treatments used by patients were collected. Concordance between each PRO and CRO was determined using percent concordance and concordance index (C-statistic) by logistic regression analysis. RESULTS: A total of 777 patients were included in the present study. All skin symptom assessment items were significantly underreported by clinicians in comparison to patients (p < 0.0001), with a low to moderate level of concordance (C-statistic range: 0.58-0.70; percent concordance range: 29-50%). The majority of patients used moisturizing creams as a prophylactic measure (65.1%), as per institutional guidelines. CONCLUSION: There were significant discrepancies between PROs and CROs when assessing breast RD. CROs alone are insufficient in measuring RD as they fail to capture the impact on patient quality of life. The study findings highlight the need for improved RD symptom assessment and support the development of a new tool with both patient and clinician components.
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Neoplasias da Mama , Radiodermite , Neoplasias da Mama/radioterapia , Feminino , Humanos , Medidas de Resultados Relatados pelo Paciente , Estudos Prospectivos , Qualidade de Vida , Radiodermite/diagnóstico , Radiodermite/etiologiaRESUMO
BACKGROUND: Synchronous bilateral breast cancer (SBBC) is rare and there is little evidence describing organs at risk (OAR) and limits to the heart and lungs caused by radiotherapy (RT). Quantifying mean heart dose (MHD) and mean lung dose (MLD) from RT in this patient cohort may lead to better understanding of doses to OAR and resultant effects on clinical outcomes. The primary objective was to assess median MHD and MLD in SBBC, while secondary aims included analyses of 1) factors associated with MHD and MLD, 2) V5 and V20 values and 3) factors associated with clinical outcomes. METHODS: Patients planned for adjuvant bilateral whole breast/chest wall (WB) RT from a single institution treated in 2011-2018 were included. Median MHD and MLD (Gy) were stratified by hypofractionated (42.56 Gy/16 fractions, HFRT) and conventional fractionation (50 Gy/ 25 fractions, CFRT) and summarized separately based on the following treatments: 1) locoregional RT, WB tangential RT either 2) no boost 3) sequential boost or 4) simultaneous integrated boost. MHD, MLD, lung V5 and V20 values, and demographics were collected. Linear regression analyses identified factors associated with MHD and MLD and factors associated with clinical outcomes. RESULTS: A total of 88 patients were included. The median MHD for HFRT and CFRT was 1.99 Gy and 2.94 Gy, respectively. The median MLD for HFRT and CFRT was 6.00 Gy and 10.08 Gy, respectively. MHD and MLD were significantly associated with the occurrence of a cardiac or pulmonary event post-radiation. Patients who had a mastectomy or tumoral muscle involvement were more likely to develop a local recurrence, metastasis or new primary while patients who had a lumpectomy or tumor with a positive estrogen receptor status were less likely to experience these events. CONCLUSIONS: Further investigation should be conducted to identify SBBC RT techniques that mitigate dose to OARs to improve clinical outcomes in bilateral breast patients.
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Neoplasias da Mama , Neoplasias da Mama/radioterapia , Feminino , Coração , Humanos , Mastectomia , Órgãos em Risco , RadiometriaRESUMO
PURPOSE: Radiation dermatitis (RD) is a side effect that frequently arises during radiotherapy (RT) in breast cancer patients. The present study investigates possible predictive factors of RD, as well as the use of skin treatments to manage symptoms. METHODS: Demographic and treatment characteristics were collected retrospectively, while skin symptoms and treatments were collected prospectively for patients who received adjuvant RT between December 2013 and November 2015. Patients were seen weekly by clinicians throughout treatment, during which a clinician-reported survey was completed on RD symptoms and skin treatments. Possible predictive factors were correlated with skin outcomes through a univariate ordinal logistic regression analysis. RESULTS: A total of 1093 patients were included in this analysis. Predictive factors for erythema included dose fractionation (p<0.0001), tissue volume irradiated by tangential fields (p = 0.01), and administration of a boost (p = 0.005). High BMI (≥30 kg/m2) (p = 0.0004) and boost (p = 0.02) were predictive of edema. A dose of 50 Gy/25 (p<0.0001) and a high irradiated tissue volume (p = 0.0001) were predictive of desquamation. A dose of 50 Gy/25 (p = 0.0005) and high BMI (p = 0.02) were predictors of pain. Bolus use was the only factor associated with bleeding (p = 0.02). Patients who developed desquamation were likely to receive corticosteroids/antihistamines (p<0.0001), topical antibiotics/antifungals (p<0.001), and dressings (p<0.0001). CONCLUSION: The findings of this study provide evidence of potential predictors of RD and methods of symptom management based on symptom severity. Prevention of RD is needed among high-risk groups, such as patients with a high BMI or receiving a standard fractionation, boost, or bolus.
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Neoplasias da Mama/complicações , Radiodermite/etiologia , Radioterapia Adjuvante/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/radioterapia , Feminino , Humanos , Pessoa de Meia-Idade , Radiodermite/patologiaRESUMO
Previous studies demonstrate that Mycobacterium vaccae NCTC 11659 (M. vaccae), a soil-derived bacterium with anti-inflammatory and immunoregulatory properties, is a potentially useful countermeasure against negative outcomes to stressors. Here we used male C57BL/6NCrl mice to determine if repeated immunization with M. vaccae is an effective countermeasure in a "two hit" stress exposure model of chronic disruption of rhythms (CDR) followed by acute social defeat (SD). On day -28, mice received implants of biotelemetric recording devices to monitor 24-h rhythms of locomotor activity. Mice were subsequently treated with a heat-killed preparation of M. vaccae (0.1 mg, administered subcutaneously on days -21, -14, -7, and 27) or borate-buffered saline vehicle. Mice were then exposed to 8 consecutive weeks of either stable normal 12:12 h light:dark (LD) conditions or CDR, consisting of 12-h reversals of the LD cycle every 7 days (days 0-56). Finally, mice were exposed to either a 10-min SD or a home cage control condition on day 54. All mice were exposed to object location memory testing 24 h following SD. The gut microbiome and metabolome were assessed in fecal samples collected on days -1, 48, and 62 using 16S rRNA gene sequence and LC-MS/MS spectral data, respectively; the plasma metabolome was additionally measured on day 64. Among mice exposed to normal LD conditions, immunization with M. vaccae induced a shift toward a more proactive behavioral coping response to SD as measured by increases in scouting and avoiding an approaching male CD-1 aggressor, and decreases in submissive upright defensive postures. In the object location memory test, exposure to SD increased cognitive function in CDR mice previously immunized with M. vaccae. Immunization with M. vaccae stabilized the gut microbiome, attenuating CDR-induced reductions in alpha diversity and decreasing within-group measures of beta diversity. Immunization with M. vaccae also increased the relative abundance of 1-heptadecanoyl-sn-glycero-3-phosphocholine, a lysophospholipid, in plasma. Together, these data support the hypothesis that immunization with M. vaccae stabilizes the gut microbiome, induces a shift toward a more proactive response to stress exposure, and promotes stress resilience.