Analysis of multi-level barriers to physical activity among nursing students using regularized regression.

Physical inactivity is a growing societal concern with significant impact on public health. Identifying barriers to engaging in physical activity (PA) is a critical step to recognize populations who disproportionately experience these barriers. Understanding barriers to PA holds significant importance within patient-facing healthcare professions like nursing. While determinants of PA have been widely studied, connecting individual and social factors to barriers to PA remains an understudied area among nurses. The objectives of this study are to categorize and model factors related to barriers to PA using the National Institute on Minority Health and Health Disparities (NIMHD) Research Framework. The study population includes nursing students at the study institution (N = 163). Methods include a scoring system to quantify the barriers to PA, and regularized regression models that predict this score. Key findings identify intrinsic motivation, social and emotional support, education, and the use of health technologies for tracking and decision-making purposes as significant predictors. Results can help identify future nursing workforce populations at risk of experiencing barriers to PA. Encouraging the development and employment of health-informatics solutions for monitoring, data sharing, and communication is critical to prevent barriers to PA before they become a powerful hindrance to engaging in PA.

Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma: Meta-Analysis and International Stereotactic Radiosurgery Society Practice Guidelines.

This systematic review and meta-analysis reports on outcomes and hepatic toxicity rates after stereotactic body radiation therapy (SBRT) for liver-confined hepatocellular carcinoma (HCC) and presents consensus guidelines regarding appropriate patient management. Using the Preferred Reporting Items for Systemic Review and Meta-Analyses guidelines, a systematic review was performed from articles reporting outcomes at ≥5 years published before October 2022 from the Embase, MEDLINE, Cochrane, and Scopus databases with the following search terms: ("stereotactic body radiotherapy" OR "SBRT" OR "SABR" OR "stereotactic ablative radiotherapy") AND ("hepatocellular carcinoma" OR "HCC"). An aggregated data meta-analysis was conducted to assess overall survival (OS) and local control (LC) using weighted random effects models. In addition, individual patient data analyses incorporating data from 6 institutions were conducted as their own subgroup analyses. Seventeen observational studies, comprising 1889 patients with HCC treated with ≤9 SBRT fractions, between 2003 and 2019, were included in the aggregated data meta-analysis. The 3- and 5-year OS rates after SBRT were 57% (95% confidence interval [CI], 47%-66%) and 40% (95% CI, 29%-51%), respectively. The 3- and 5-year LC rates after SBRT were 84% (95% CI, 77%-90%) and 82% (95% CI, 74%-88%), respectively. Tumor size was the only prognostic factor for LC. Tumor size and region were significantly associated with OS. Five-year LC and OS rates of 79% (95% CI, 0.74-0.84) and 25% (95% CI, 0.20-0.30), respectively, were observed in the individual patient data analyses. Factors prognostic for improved OS were tumor size <3 cm, Eastern region, Child-Pugh score ≤B7, and the Barcelona Clinic Liver Cancer stage of 0 and A. The incidence of severe hepatic toxicity varied according to the criteria applied. SBRT is an effective treatment modality for patients with HCC with mature follow-up. Clinical practice guidelines were developed on behalf of the International Stereotactic Radiosurgery Society (ISRS).

Changes in life satisfaction among middle-aged adults living alone over a 12-year span.

This secondary analysis used data collected for the Korean Longitudinal Study of Aging from 2006 to 2018 to examine changes in life satisfaction among middle-aged adults living alone in South Korea. Individuals who were over 45 years of age, lived alone at the time of the first data collection wave, and responded at least twice to the survey over the 12-year study period were included in the final linear mixed model (N = 124). Life satisfaction increased for those who had increased assets, were widowed, and had more frequent contact with acquaintances (i.e., once a month and once a week compared with once a year). Life satisfaction decreased as the number of chronic illnesses increased for underweight individuals compared with normal weight or overweight individuals and for depressed versus non-depressed individuals. This study's findings indicate that increased social support is beneficial for middle-aged marginalized individuals, including those who are economically disadvantaged, have few social interactions, are underweight, and have chronic illnesses.

Treatment Outcomes of Proton Beam Therapy for Esophageal Squamous Cell Carcinoma at a Single Institute.

Recently, proton beam therapy (PBT) has gathered attention for improving outcomes and reducing toxicities in various cancers; however, the evidence for esophageal squamous cell carcinoma (ESCC) is lacking. Our study retrospectively evaluated the outcomes of PBT for ESCC patients at a single institute. The patients treated with PBT between November 2015 and February 2022 were included in the study, excluding those with distant metastases or those that had undertaken prior treatment for esophageal cancer (EC). The 3 year overall survival (OS) and progression-free survival (PFS) rates were calculated based on stage grouping. The patterns of failure, salvage treatment outcomes, and toxicity profiles were analyzed. The median follow-up was 35.1 months, and 132 patients were analyzed. The 3 year OS and PFS rates for the stages I, II, and III disease cases were 81.0%, 62.9%, and 51.3%; and 70.6%, 71.8%, and 39.8%, respectively. Nineteen patients presented isolated local progression, ten patients underwent appropriate salvage procedures, and nine were successfully salvaged. One patient with isolated regional progression was also salvaged. No cases of grade ≥ 4 lymphopenia were observed. One patient had grade 4 pericardial effusion and esophageal fistula. For the patients with ESCC, PBT is an effective treatment in terms of the survival outcomes and toxicities.

Anticholinergic Burden and Xerostomia in Critical Care Settings.

BACKGROUND: Although previous studies have established the association of medications with anticholinergic adverse effects and xerostomia, anticholinergic burden and xerostomia in critical care settings are poorly characterized. The objective of this study was to determine the impact of medication burdens associated with anticholinergic adverse effects, particularly the occurrence of xerostomia (dry mouth) in a critical care setting. In addition, this study explored the correlation between the timing of the first instance of xerostomia and the administration timing of medication known to have anticholinergic adverse effects. METHODS: A retrospective case-control study was used with the MIMIC (Medical Information Mart for Intensive Care) III database. The MIMIC-III clinical database is a publicly available, deidentified, health-related database with more than 40 000 patients in critical care units from 2001 to 2012. Cases of xerostomia (n = 1344) were selected from clinical notes reporting "dry mouth," "xerostomia," or evidence of pharmacological treatment for xerostomia; control (n = 4032) was selected using the propensity analysis with 1:3 matching on covariates (eg, age, sex, race, ethnicity, and length of stay). The anticholinergic burden was quantified as the cumulative effect of anticholinergic activities using the Anticholinergic Burden Scale. RESULTS: Anticholinergic burden significantly differed between xerostomia patients and control subjects (P = .04). The length of stay was a statistically significant factor in xerostomia. The probability of developing the symptom of xerostomia within 24 hours was .95 (95%) for patients of xerostomia. CONCLUSIONS: Anticholinergic Burden Scale is associated with xerostomia in the critical care setting, particularly within 24 hours after admission. It is crucial to carefully evaluate alternative options for medications that may have potential anticholinergic adverse effects. This evaluation should include assessing the balance between the benefits and harms, considering the probability of withdrawal reactions, and prioritizing deprescribing whenever feasible within the initial 24-hour period.

Development of a Pediatric Behavioral Early Warning Scale (Pedi-BEWS) for Children.

Background and Purpose: The prevention of aggressive behavior in child and adolescent inpatient settings is essential. However, it can be difficult to prompt a quick appropriate intervention without an early warning scale for the prevention and management of behavioral emergencies in a psychiatric inpatient adolescent unit. Behavioral emergencies often result in restraint/seclusion and/or administration of psychotropic medications. The objectives are to develop and evaluate the Pediatric Behavioral Early Warning Scale (Pedi-BEWS) as a screening tool to prompt quick appropriate interventions and to decrease incidents of restraint/seclusion and/or administration of psychotropic medications. Methods: A two-phase methodological design was applied. A total of 447 inpatients and 21 nurses were used to test internal consistency reliability and validity. Results: Receiver operating characteristic curve areas for the developed instrument were calculated to be 0.890 (cognition), 0.959 (affect), and 0.951 (behavior). The overall Pedi-BEWS indicated high reliability (Cronbach's alpha = .98). Conclusions: The Pedi-BEWS shows high internal consistency and validity. The use of the newly developed tool may reduce or eliminate episodes of seclusion and restraint for pediatric patients with a behavioral problem. In addition, the tool has the potential to enhance psychiatric nurses' assessment skills and competencies. The use of the newly developed Pedi-BEWS can promote an appropriate and timely nursing assessment and intervention before the deterioration in psychiatric nursing practice.

The use of physical restraints and PRN medications in adolescent psychiatric inpatient units.

PROBLEM: Although physical restraint practices and psychotropic/sedative pro re neta (PRN, as needed) medications have been commonly used for managing inpatient aggression, little is known about the characteristics of adolescents who receive them in psychiatric adolescent inpatient units. We aimed to determine the relationship between the use of physical restraints and psychotropic/sedative PRN medications, and to characterize individual attributes, substance use, clinical factors, and time of the first restraint episodes of the use of physical restraints and psychotropic/sedative PRN medications. METHODS: A retrospective case-control study approach was used with the data from electronic health records at a pediatric psychiatric hospital in the United States. Descriptive statistics, χ2 , multivariate logistic regression, and Cox proportional hazard model were used. FINDINGS: Participants of younger age and participants with a longer length of stay were significantly associated with the use of physical restraints and psychotropic/sedative PRN medications, although the substance-related risks were not significantly associated with the use of restraints. Physical restraints were more likely to have occurred soon after the admission and tapered off as the length of stay increased. CONCLUSIONS: This study provides important information in understanding the risk factors of the use of restraints and psychotropic/sedative PRN medications in psychiatric adolescent inpatient units.

Efficacy of Prophylactic Cranial Irradiation According to the Risk of Extracranial Recurrence in Limited-Stage Small Cell Lung Cancer.

PURPOSE: We aimed to evaluate the effectiveness of prophylactic cranial irradiation (PCI) for "early brain metastasis", which occurs before extracranial recurrence (ECR), and "late brain metastasis", which occurs after ECR, in limited-stage small cell lung cancer (LS-SCLC). Materials and Methods: We retrospectively analyzed 271 LS-SCLC patients who underwent definitive chemoradiation. All patients were initially staged with brain magnetic resonance imaging and positron emission tomography. Intracranial recurrence (ICR), ECR, progression-free rate (PFR), and overall survival (OS) were analyzed as clinical endpoints. The competing risk of the first recurrence with ICR (ICRfirst) was evaluated. Significantly associated variables in multivariate analysis of ECR were considered as ECR risk factors. Patients were stratified according to the number of ECR risk factors. RESULTS: The application of PCI was associated with higher PFR (p=0.008) and OS (p=0.045). However, PCI was not associated with any of the clinical endpoints in multivariate analysis. The competing risk of ICRfirst was significantly decreased with the application of PCI (hazard ratio, 0.476; 95% confidence interval, 0.243 to 0.931; p=0.030). Stage III disease, sequential, and stable disease after thoracic radiation were selected as ECR risk factors. For patients without these risk factors, the application of PCI was significantly associated with increased OS (p=0.048) and a decreased risk of ICRfirst (p=0.026). CONCLUSION: PCI may play a role in preventing early brain metastasis rather than late brain metastasis after ECR, suggesting that only patients with a low risk of ECR may currently benefit from PCI.

Analysis of Once-Daily Thoracic Radiotherapy Dose According to the Underlying Lung Disease in Patients with Limited-Stage Small Cell Lung Cancer Undergoing Concurrent Chemoradiotherapy.

PURPOSE: In the treatment of concurrent chemoradiotherapy (CCRT) in limited-stage small cell lung cancer, the optimal once-daily radiotherapy (RT) dose/fractionation remain unclear although it is the most frequently used. Therefore, this study aimed to compare the treatment outcomes and toxicities of modest dose RT (≤ 54 Gy) with those of standard dose RT (> 54 Gy) and investigate the benefit of the high dose based on patient factors. MATERIALS AND METHODS: Since 2004, our institution has gradually increased the thoracic RT dose. Among the 225 patients who underwent CCRT, 84 patients (37.3%) received > 54 Gy. Because the patients treated with RT > 54 Gy were not randomly assigned, propensity score matching (PSM) was performed. RESULTS: The proportion of patients treated with > 54 Gy increased over time (p=0.014). Multivariate analysis revealed that the overall tumor stage and dose > 54 Gy (hazard ratio, 0.65; p=0.029) were independent prognostic factors for overall survival (OS). PSM confirmed that thoracic RT doses of > 54 Gy showed significantly improved progression-free survival (3-year, 42.7% vs. 24.0%; p < 0.001) and OS (3-year, 56.2% vs. 38.5%; p=0.003). Sensitivity analysis also showed that 60 Gy resulted in better survival than 54 Gy. However, in patients with underlying lung disease, OS benefit from > 54 Gy was not observed but considerable rates of severe pulmonary toxicities were observed (p=0.001). CONCLUSION: Our analysis supports that the 60 Gy RT dose should be considered in the once-daily regimen of CCRT for limited-stage small cell lung cancer without underlying lung disease, but RT dose > 54 Gy did not seem to benefit for patients with chronic obstructive pulmonary disease or interstitial lung disease. Further study is needed to validate these results.

Oral conditions and other symptoms among older persons in long-term care facilities during the end of life.

AIMS: The purpose was to examine the association between oral conditions and other symptoms in long-term care facilities during the last days of life. METHODS: A retrospective case-control study approach was used in this study, with the Minimum Data Set (MDS, ver. 3.0 2015) that was maintained and administrated by the Centers for Medicare and Medicaid Services (CMS). Residents with oral conditions (n = 4304) were selected with any oral conditions (e.g., ulcers, inflamed/bleeding gums, mouth/facial pain). The control cases (n = 12 912) were selected using propensity analysis. RESULTS: Oral conditions had significant impacts on depression, poor appetite, pain, shortness of breath, and constipation. Although no statistically significant differences in trouble sleeping, vomiting, internal bleeding, and dehydration were found between the cases with oral conditions and the control, more residents with oral conditions reported trouble sleeping and dehydration compared to the control. CONCLUSIONS: It is important to provide preventive and proactive intervention for oral conditions, not only to minimize the negative effects of oral conditions on other symptoms in long-term care facilities, but also to share philanthropic support with people who might be suffering other symptoms due to oral conditions at the end of life.

Examining a Fatigue Management Model in Older Individuals.

PURPOSE: The aim of this study was to examine a fatigue model for older individuals based on the theory of unpleasant symptoms. RESEARCH DESIGN: The research design used was a secondary data analysis of the "Patient-Reported Outcomes Measurement Information System Profiles-Health Utilities Index" data set. METHODS: Multiple regression analysis and path analyses were used to examine hypothesized model paths. RESULTS: A number of comorbidities, pain, sleep, depression, anxiety, education, and sensory impairment were significant predictors of fatigue. Higher fatigue scores predicted lower physical, social, and cognitive performances, as well as worse perceived health and quality of life (QOL). In addition, the identified fatigue outcomes mediated the relationship between fatigue and QOL. CONCLUSIONS: Future research should be directed toward exploring other risk factors of fatigue and examining feedback loops depicted in the theory of unpleasant symptoms. CLINICAL RELEVANCE TO THE PRACTICE OF REHABILITATION NURSING: Rehabilitation nurses should closely monitor and manage the identified fatigue-influencing factors to improve older individuals' performance, perceived health, and QOL.

Psychiatric Hospitalization Associated with Emergency Department Visits.

Psychiatric boarding in an emergency department (ED) has personal and social consequences that can increase healthcare expenditure through a variety of inter-related mechanisms. This study aimed to compare health outcomes (e.g., length of stays, the severity of illness) between patients who stayed in an emergency department and those who did not visit an emergency department before the hospitalization. With the National Inpatient Sample dataset in the United States, we compared psychiatric inpatient service utilization outcomes between those who had stated in an emergency department and those who had not. Results: Among those with ED visits, the in-hospital mortality was 0.80 times lower (95% CI: 0.79-0.81). The length of hospital stays and the total charges were not significantly different from those without ED visits. The integration of primary care with psychiatric inpatient services can improve the management of psychiatric prevention and treatment, with the reduction of ED visits. This study provides an essential value in reducing emergency visits as the plan for psychiatric inpatient utilization to achieve more cost-effective and adequate healthcare outcomes.

Physical Activity Interventions for Colorectal Cancer Survivors: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

BACKGROUND: Physical activity (PA) has been shown to improve total mortality and colorectal-specific mortality risk; however, colorectal cancer (CRC) survivors have lower rates of PA compared with survivors with other types of cancers. OBJECTIVE: To examine the effect of PA interventions on CRC survivors. METHODS: A systematic review and meta-analysis were conducted to identify randomized controlled trials that met the inclusion criteria, which included an intervention designed to increase PA and more than 1 outcome of interest. Random effects of the meta-analyses were performed using Review Manager 5.3. RESULTS: Eight publications representing 7 randomized controlled trials of 803 participants were identified. All studies used a combination of behavioral change methods. Physical activity interventions significantly improved disease-specific quality of life, PA level, and maximum amount of oxygen and did not show significant improvements for fatigue and body mass index among CRC survivors. CONCLUSIONS: We provided evidence that PA interventions were effective in improving disease-specific quality of life, PA level, and maximum amount of oxygen; however, they did not improve fatigue and body mass index. Further randomized controlled trials are needed to determine the optimal mode of delivering PA intervention for CRC survivors. IMPLICATIONS FOR PRACTICE: As the survival rate of patients with CRC increases, survivors of CRC need to increase PA in a community setting after completing primary treatments. Effective and efficient modes of PA intervention delivery could improve health-related outcomes and address specific barriers for CRC survivors.

Exploring Impact of Marijuana (Cannabis) Abuse on Adults Using Machine Learning.

Marijuana is the most common illicit substance globally. The rate of marijuana use is increasing in young adults in the US. The current environment of legalizing marijuana use is further contributing to an increase of users. The purpose of this study was to explore the characteristics of adults who abuse marijuana (20-49 years old) and analyze behavior and social relation variables related to depression and suicide risk using machine-learning algorithms. A total of 698 participants were identified from the 2019 National Survey on Drug Use and Health survey as marijuana dependent in the previous year. Principal Component Analysis and Chi-square were used to select features (variables) and mean imputation method was applied for missing data. Logistic regression, Random Forest, and K-Nearest Neighbor machine-learning algorithms were used to build depression and suicide risk prediction models. The results showed unique characteristics of the group and well-performing prediction models with influential risk variables. Identified risk variables were aligned with previous studies and suggested the development of marijuana abuse prevention programs targeting 20-29 year olds with a regular depression and suicide screening. Further study is suggested for identifying specific barriers to receiving timely treatment for depression and suicide risk.

A Cohort Model of Mentoring as Facilitator to the Transition to an Academic Nurse Faculty Position Following Completion of a PhD.

ABSTRACT: Successful transition to an academic nurse educator role is challenging; it is necessary to identify facilitators and barriers that aide or hinder this process. This study used an autoethnographic qualitative design to explore the lived experiences of a cohort of faculty during their transition into a tenure-track role. Three facilitators (noncompetitive environment, resource sharing, and cohort approach) and two barriers (work-life balance and intrusion of old habits) emerged as themes. A cohort model can be a valuable facilitator for a successful transition. Multitiered mentoring further aided in the transition.

Description and comparison of exam wrapper learning strategy use in baccalaureate and associate degree nursing students: A descriptive study.

BACKGROUND: Exam wrapper, a structured self-regulated learning strategy, assists students to review study habits and performance on an exam with the goal of improving future study habits. Little is known about the use of this strategy in nursing students, particularly associate degree students. OBJECTIVES: To describe and compare demographic characteristics, study habits, reasons for getting content wrong on an exam and future study plans between associate degree and baccalaureate nursing students. DESIGN: A cross sectional, descriptive comparative study of exam wrapper use in associate degree and baccalaureate nursing students. SETTINGS: A medium-sized public university and small private college in the northeastern United States. PARTICIPANTS: A convenience sample 102 prelicensure baccalaureate (n = 63) and associate degree (n = 39) nursing students. Mean age of 21.9 ± 5.6, GPA of 3.46 ± 0.38, 7% male, 57% commuter students, 75% employed an average of 14 ± 11.4 h per week. METHODS: Data were collected by course faculty during an in-class exam review following a multiple-choice examination. Students completed a demographic form and exam wrapper that assessed pre-exam study habits, reasons for getting items wrong on an exam and future study habits. RESULTS: Associate degree students had lower GPAs (3.19 vs 3.57, p = .000), were older (27 vs 19.2, p = .000), more often commuted (100% vs 31%, p = .000), were employed (95% vs 65%, p < .001), were more likely to study at home (39.5% vs 13.1%, p = .000) and spent significantly longer on each study activity (p = .000) than baccalaureate students. When comparing reasons for getting a question wrong and intended study habits, baccalaureate and associate degree students did not differ. CONCLUSIONS: Use of the exam wrapper strategy allows nursing students at all levels of prelicensure education to actively reflect upon their learning with the goal of improving future learning.

Correlation between 3D scanner image and MRI for tracking volume changes in head and neck cancer patients.

INTRODUCTION: We investigated the correlation between optical surface imaging using a three-dimensional (3D) scanner and magnetic resonance imaging (MRI) for suggesting feasibility in the clinical process of tracking volume changes in head and neck patients during radiation treatment. METHODS: Ten patients were divided into two groups depending on the location of their tumor (i.e., right or left side). With weekly imaging data, the change in volume based on MRI was evaluated during the treatment course. Four volumes of interest (VOIs) were calculated on the 3D surface image of the facial and cervical areas using an optical 3D scanner, and the correlation between volumetric parameters were analyzed. RESULTS: The target volume changed significantly overall for both groups. The changes parotid volume reduced by up to 3.8% and 28.0% for groups A (right side) and B (left side), respectively. In Group A, VOI 1 on the facial area and VOI 3 on the cervical area decreased gradually during the treatment course by up to 3.3% and 10.7%, respectively. In Group B, only VOI 4 decreased gradually during the treatment course and reduced by up to 9.2%. In group A, the change in target volume correlated strongly with right-side parotid, VOI 1, and VOI 3, respectively. The parotid also showed strong correlations with VOIs (P < 0.01). The weight loss was strongly correlated with either PTV or parotid without statistical significance (P > 0.05). In group B (left side), the change in target volume correlated strongly with each volumetric parameter, including weight loss. For individual patient, PTV showed more correlation with VOIs on the cervical area than VOIs on the facial area. CONCLUSIONS: An optical 3D scanner can be applied to track changes in volume without radiation exposure during treatment and the optical surface image correlated with MRI.

Combining Radiomics and Blood Test Biomarkers to Predict the Response of Locally Advanced Rectal Cancer to Chemoradiation.

BACKGROUND/AIM: A noninvasive method for predicting a patient's response to neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer would be useful because this would help determine the subsequent treatment strategy. Two types of noninvasive biomarkers have previously been studied, based on radiomics and based on blood test parameters. We hypothesized that a combination of both types would provide a better predictive power, and this has not previously been investigated. PATIENTS AND METHODS: Data from 135 patients with locally advanced rectal cancer who underwent nCRT were retrospectively allocated into training and validation cohorts in a 2:1 ratio. Sixty-five radiomics features were extracted from tumors segmented on T2-weighted magnetic resonance images. An elastic net was applied to generate four models for discerning the patients with good responses to nCRT based on radiomics features (model R), blood biomarkers (model B), both (model RB), and a linear combination of models R and B (model R+B). RESULTS: Among 65 radiomics features, 17 were selected as robust features for model development. The AUC values of model R, model B, model RB, and model R+B achieved 0.751, 0.627, 0.785, and 0.711 in the training cohort (n=90), and 0.705, 0.603, 0.679, and 0.705 in validation cohort (n=45), respectively. In the entire cohort, models RB and R+B demonstrated a significantly better performance than model B but not R. There was no correlation between the scores of models R and B (p=0.76). Radiomics features had a greater influence than blood biomarkers on models RB and R+B. CONCLUSION: A non-redundancy between radiomics features and blood-based biomarkers was observed. Furthermore, radiomics features are more valuable in terms of predicting response to nCRT. The importance of combining non-invasive biomarkers in future investigations is highlighted.

Three-dimensional versus four-dimensional dose calculation for breast intensity-modulated radiation therapy.

OBJECTIVE: To analyze the effect of intra- and interfractional motion during breast intensity modulated radiation therapy (IMRT) by calculating dose distribution based on four-dimensional computed tomography (4DCT). METHODS: 20 patients diagnosed with left breast cancer were enrolled. Three-dimensional CT (3DCT) along with 10 phases of 4DCT were collected for each patient, with target volumes independently delineated on both 3DCT and all phases of 4DCT. IMRT plans were generated based on 3DCT (43.2 Gy in 16 fractions). The plan parameters for each segment were split into phases based on time duration estimates for each respiratory phase, with phase-specific dose distributions calculated and summated (4D-calculated dose). The procedure is repeated for 16 fractionations by randomly allocating starting phase using random-number generation to simulate interfractional discrepancy caused by different starting phase. Comparisons of plan quality between the original and 4D-calculated doses were analyzed. RESULTS: There was a significant distortion in 4D-calculated dose induced by respiratory motion in terms of conformity and homogeneity index compared to those of the original 3D plan. Mean doses of the heart and the ipsilateral lung were significantly higher in the 4D-calculated doses compared to those of the original 3D plan (0.34 Gy, p = 0.010 and 0.59 Gy, p < 0.001), respectively). The mean internal mammary lymph node (IMN) dose was significantly greater in the 4D-calculated plan, compared to the original 3D plan (1.42 Gy, p < 0.001). CONCLUSIONS: IMN doses should be optimized during the dose-calculation for the free-breathing left breast IMRT. ADVANCES IN KNOWLEDGE: The interplay effect between respiratory motion and multileaf collimator modulation caused discrepancies in dose distribution, particularly in IMN.