Left-sided Breast Cancer Research Articles

Shoulder Pain, Kinesiophobia, Emotional State and Muscle Strength in Breast Cancer Surgery Patients: A Cross-Sectional Study

Breast cancer is the most common type of cancer in women. The life expectancy of patients is increasing with advances in treatment. However, lymphovascular, musculoskeletal, and psychogenic complications are reported to be expected in the follow-up period after breast cancer surgery. Kinesiophobia is the behavior of avoiding movement for fear of increased pain. Research on the frequency and interrelationships of kinesiophobia and other complications in the follow-up period is limited. Aim: We aim to evaluate shoulder pain, kinesiophobia, emotional state and muscle strength in female patients who have undergone breast cancer surgery and are in the follow-up period and to examine the relationship between these factors. Materials and Methods: A total of 50 female patients who underwent unilateral breast cancer surgery and were using aromatase inhibitors were included in this cross-sectional descriptive study. Demographic data, details of the surgical procedure and medical treatment information were recorded from the patient files. Hand grip muscle strength was measured by hand dynamometer, the Beck Depression Scale assessed emotional state, and the Tampa Kinesiophobia Scale assessed fear of movement. A Beck Depression Scale score of 10 and above and a Tampa Kinesiophobia Scale of 37 and above were considered significant. Results: The mean age of 50 female patients was 59.31 ± 11.19 years. Sixty percent of the patients had undergone surgery on the right breast and 40% on the left breast. Shoulder pain (n:31) was present in 62%. There were statistically significant correlations between pain and the Tampa kinesiophobia scale and the Beck depression scale (p:0.042, p:0.038). Kinesiophobia was present in 74% of the patients, and 64% had moderate to severe depression. The mean of the Tampa Kinesiophobia scale was 42.86±8.81, and the mean of the Beck depression scale was 15.19±10.98. When the relationship between kinesiophobia and depression was evaluated, a statistically positive significant relationship was found between them (p=0.005, r=0.410). The hand grip strength was 22.16±5.00 kg on the right and 18.22±5.10 kg on the left in patients who underwent left-sided breast cancer surgery. A significant difference was found in the left- and right-hand grip strength of those who underwent left-sided surgery for breast cancer (p

Impact of deep inspiration breath hold, surface-guided radiotherapy, and daily CBCT on the organs at risk in breast cancer radiotherapy

The goal of the study was to assess the impact of deep inspiration breath hold technique (DIBH), surface-guided radiotherapy (SGRT), and daily kilovoltage cone-beam computed tomography (kV-CBCT) on the dose to organs at risk (OAR) in left-sided breast cancer radiotherapy. Twenty-six consecutive left-sided breast cancer patients treated using Volumetric Intensity Modulated Arc Therapy (VMAT), DIBH, SGRT, and a hypofractionated regimen were retrospectively evaluated in this study. Dose parameters were extracted from dose-volume histograms (DVH). The Wilcoxon Matched Pairs test was used to test dose parameters obtained in free breathing (FB) and DIBH for statistical significance. Multivariable analysis of variance (ANOVA) and receiver operating characteristics (ROC) analysis were used to identify parameters and cut-off points associated with the reduction of the mean heart dose (MHD) by DIBH. Based on published models, the risk of cardiac and lung toxicity (pneumonitis) using SGRT or daily kV-CBCT was estimated and compared. DIBH substantially reduced the MHD (median, 43.6%; range, 4.2% to 75.1%; P < 0.00001). The risk of cardiac toxicity using SGRT increased by 1%, compared to 3.6% to 20.5% using daily kV-CBCT. No significant difference in the risk of radiation-induced pneumonitis using SGRT versus daily kV-CBCT was detected. The ANOVA revealed the relative increase of the left lung volume by DIBH as the only significant impact factor for the MHD. The ROC analysis of this parameter showed an area under the curve (AUC) of 0.89 (95%CI, 0.71 to 0.98; P < 0.0001). DIBH can substantially reduce the MHD in left-sided breast cancer patients treated with modern radiotherapy techniques and hypofractionation. Patient setup using SGRT compared to daily kV-CBCT may be the preferred option for many patients. In our patient cohort, the relative reduction of the left lung volume by DIBH can be used as a predictor to select patients who benefit from DIBH.

Improvement of plan quality in whole-breast radiation following BCS using feasibility DVH by less-experienced planners.

Variability in plan quality of radiotherapy is commonly attributed to the planner's skill rather than technological parameters. While experienced planners can set reasonable parameters before optimization, less experienced planners face challenges. This study aimed to assess the quality of volumetric-modulated arc therapy (VMAT) in patients with left-sided breast cancer following breast-conserving surgery. Twenty-eight patients requiring whole-breast irradiation were randomly selected for inclusion. Each patient underwent two VMAT treatment plans: one optimized by an experienced planner (VMAT-EXP group) and the other designed by a less experienced planner using feasibility dose-volume histogram (FDVH) parameters from PlanIQ (VMAT-FDVH group). Both plans aimed to deliver a prescription dose of 50Gy in 25 fractions to the planning target volume (PTV). Dosimetry parameters for the PTV and organs at risk (OARs) were compared between the two groups. Both the VMAT-EXP and VMAT-FDVH groups met the clinical plan goals for PTV and OARs. VMAT-FDVH demonstrated a PTV coverage and homogeneity comparable to those of VMAT-EXP. Compared to VMAT-EXP plans, VMAT-FDVH plans resulted in a significant reduction in the mean ipsilateral lung dose, with an average decrease of 0.9Gy (8.5Gy vs. 7.6Gy, P < 0.001). The V5Gy and V20Gy of the ipsilateral lung were also reduced by 3.2% and 1.8%, respectively. Minor differences were observed in the heart, contralateral lung, breast, and liver. Personalized objectives derived from the feasibility DVH tool facilitated the generation of acceptable VMAT plans. Less experienced planners achieved lower doses to the ipsilateral lung while maintaining adequate target coverage and homogeneity. These findings suggest the potential for the effective use of VMAT in in patients with left-sided breast cancer following breast-conserving surgery, especially when guided by feasibility DVH parameters.

Evaluation and Improving Treatment Plans of Gated Radiotherapy in Left-Sided Breast Cancer Patients Using Respiratory Motion Management System for Deep Inspiration Breath-Hold (DIBH)

Background: One essential part of treating breast cancer is radiation therapy. Patients with breast cancer are more likely to develop cardiac problems and die if they accidentally expose their hearts to radiation. In order to minimize radiation exposure to the heart, the deep inspiration breath-hold technique (DIBH) has been implemented into clinical practice. This study aimed to assess the use of the Varian Respiratory Motion Management System (RGSC) for radiation application in DIBH, with a focus on dosimetric plan comparison and treatment planning during free breathing (FB) and DIBH Methods and Material: This prospective clinical trial comprised 100 patients with left-sided breast cancer who had undergone breast-conserving surgery. Gating control and the RGS system were employed for therapy application. Analytical anisotropic algorithm (AAA) was used to generate dual treatment plans after CT data were obtained in FB and DIBH. Using the Dose Volume Histogram (DVH), dosimetric output parameters of organs at risk were compared. Results: The RGSC is connected to the LINAC systems and enables con- tinuous, touchless respiratory motion tracking using a camera. After each patient underwent dual treatment planning, 50 patients received treatment in Intensity Modulated Radiotherapy (IMRT) using DIBH, while 50 more patients received treatment in IMRT using Free Breath (FB). The mean cardiac dose reduction for DIBH in these patients was 7.23 to 3.41 Gy when compared to FB. Conclusion: The current data demonstrate that RT could greatly lower mean doses to the heart and high-dose locations by implementing the DIBH approach.

Dosimetric benefit and clinical feasibility of deep inspiration breath-hold and volumetric modulated arc therapy-based postmastectomy radiotherapy for left-sided breast cancer

To evaluate the dosimetric benefits and clinical feasibility of deep inspiratory breath-hold (DIBH) combined with volumetric modulated arc therapy (VMAT) in left-sided postmastectomy radiotherapy (PMRT). Eligible patients with left-sided breast cancer undergoing DIBH-based PMRT were prospectively included. Chest wall, supra/infraclavicular fossa, and/or internal mammary node irradiation (IMNI) were planned with a prescription dose of 43.5 Gy in 15 fractions. VMAT plans were designed on free breathing (FB)—and DIBH-CT to compare dosimetric parameters in heart, left anterior descending artery (LAD) and lung. Cone-beam computed tomography (CBCT) was performed before and after treatment to evaluate inter- and intra-fractional setup errors. Heart position and dose variations during treatment were estimated by fusing CBCT with DIBH-CT scans.Twenty patients were included with 10 receiving IMNI. In total, 193 pre-treatment and 39 pairs pre- and post-treatment CBCT scans were analyzed. The Dmean, Dmax, and V5−40 of the heart, LAD, and left lung were significantly lower in DIBH than FB (p < 0.05 for all), except for V5 of LAD (p = 0.167). The cardiopulmonary dosimetric benefits were maintained regardless of IMNI. The inter- and intra-fractional setup errors were < 0.3 cm; and the overall estimated PTV margins were < 1.0 cm. During treatment, the mean dice similarity coefficient of heart position and the mean ratio of heart Dmean between CBCT and DIBH-CT plans was 0.95 (0.88–1.00) and 100% (70.6–119.5%), respectively. DIBH-VMAT could effectively reduce the cardiopulmonary doses with acceptable reproducibility and stability in left-sided PMRT regardless of IMNI.

A comparative analysis of patients with breast cancer with and without language barriers.

340 Background: About 20% of Americans speak a language other than English at home, among these over one-third experience language barriers when interacting in English. These populations face additional barriers, which can lead to adverse outcomes in the case of a cancer diagnosis. Diverse older adults are at highest risk for sub-optimal care and toxicity from cancer therapies due to the intensity of treatment, their age, comorbidities, in addition to the burden of historic inequities they experience due to sub-optimal communication and insufficient communication of risk. Methods: This retrospective observational study explores the role of language barriers on patient characteristics among patients diagnosed with advanced left-side breast cancer (LSBC). LSBC requires radiotherapy which can pose a risk for cardiotoxicity. Electronic medical records for N=1795 patients were extracted at a tertiary cancer center; analyses were conducted on a secure virtual research desktop using SAS 9.4. This study was IRB approved. Results: Overall, most patients were female (99.5%) and NH White, with a large proportion of Latine patients 17.8%. Most were married or had a partner (49.6%) and were on Medicare (43.2%) or private insurance (34.7%), very few were on Medicaid (5.0%). 9.7% reported a disability that left them unable to work and 13.3% of patients requested an interpreter at their last encounter. Nearly 9% of patients reported a history of heart disease. When we compared patients by those that did and did not request an interpreter as a proxy for limited English proficiency (LEP), we found that patients who were reported Spanish as their preferred language (84.8%, p&lt;.0001) were more likely to be request an interpreter. This group was followed closely by speakers from languages spoken in the Middle East and N. Africa (MENA) region (80.5%, p&lt;.0001). Conversely, we observed patients on Medicaid to be more likely to request an interpreter vs other payer types (39.3%, p&lt;.0001), finally we found significantly fewer patients with a history of heart disease experiencing language barriers. Conclusions: Our assessment demonstrates language barriers remain a significant barrier for Spanish and MENA-region breast cancer patients. Patients with language barriers may have different risk factors and unique needs that require further study. Thus, improved outcomes can be encouraged with tailored management and support for communication barriers.

Dosimetric analysis of LAD dose in left-sided breast cancer radiotherapy with deep inspiratory breath hold

Objectives To analyze the dose to the left anterior descending artery (LAD) in patients who have received radiotherapy for left breast cancer with Deep Inspiratory Breath Hold (DIBH) technique and compare it with other cardiac dosimetric parameters, as well as the accepted dose constraints. Materials and Methods 20 patients (10 prospective and 10 retrospective) were selected for this study. All patients underwent 2 non-contrast radiation planning CT scans of 2.5 mm thickness - one with DIBH and one with free breathing. Contouring was done using the Radiation Therapy Oncology Group (RTOG) guidelines. LAD was delineated and given a PRV of 3 mm and 5 mm. Dose-volume histograms (DVH) were used to obtain the data from the approved plans. Results The lung volume receiving 17 Gy in percentage, Dmean of the heart, LAD Dmean and Dmax, and the Dmean and Dmax received by 3 mm and 5 mm PRVs were both very well achieved when compared to the dose constraints given by the DBCG HYPO trial. The study found a higher correlation between the mean heart dose and the 5 mm PRV dose (R2 = 0.81 and 0.71 respectively for the mean and max dose) than the 3 mm PRV, and a positive correlation between the heart dose and LAD making it a useful structure for predicting acute cardiac events. Conclusion The study of 20 patients found that DIBH is effective to minimize cardiac dose and potentially cardiac toxicity, with heart and LAD doses being comparable or lower compared to other studies. The LAD doses recorded were significantly less than those in non-DIBH studies, demonstrating the feasibility of routine contouring and recording LAD dose in left-sided breast radiation patients. Further research is needed to determine the dosimetry and clinical consequences of the Dmean and Dmax of the 5mm PRV to the LAD.

Abstract C137: Exploring cardiotoxicity risk factors among patients diagnosed with breast cancer

Abstract Introduction Heart disease is the second most common cause of death for cancer survivors after their cancer diagnosis. Patients diagnosed with cancer, especially those with left-side breast cancer are at higher risk for treatment related toxicity. This burden is exacerbated for vulnerable patients that experience structural and chronic risk factors such as language barriers and disability which contribute to poorer survival. This study compared multi-level factors and their effect on age of diagnosis. Methods We explored a diverse population of N=1795 patient electronic medical records for patients diagnosed with left-side breast cancer and compared characteristics of patients by age, race, ethnicity, history of heart disease, disability status. Descriptive and Kruskal-Wallis ANOVA models were used to compare groups. Results The mostly female cohort of language diverse patients had an average of 66 years, most were White (64.5%), retired (52.1%), and on Medicare (43.2%). Approximately 17.8% were Latine and 13.3% needed an interpreter. Disability status was 9.7% and 8.8% had a history of heart disease. Patients diagnosed with breast cancer who were disabled were younger compared to those without a disability (60 yrs vs 67, p&amp;lt;.0001). When we compared language proficiency, we found this difference persisted as patients with a disability and were limited English were younger compared to patients that experienced neither (61yrs vs 67, p&amp;lt;.0001). Discussion This exploratory analysis is one of the first to explore the role of disability among minoritized and limited English proficient patients with breast cancer. More research is necessary to understand how to best plan and support diverse and disabled patients diagnosed with cancer to minimize their risk and improve outcomes. Citation Format: Melody K Schiaffino, Van "Vannie" K. Nguyen, Dominique Rash, Alicia Fernandez. Exploring cardiotoxicity risk factors among patients diagnosed with breast cancer [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C137.

Deep learning-based prediction of the dose-volume histograms for volumetric modulated arc therapy of left-sided breast cancer.

The advancements in artificial intelligence and computational power have made deep learning an attractive tool for radiotherapy treatment planning. Deep learning has the potential to significantly simplify the trial-and-error process involved in inverse planning required by modern treatment techniques such as volumetric modulated arc therapy (VMAT). In this study, we explore the ability of deep learning to predict organ-at-risk (OAR) dose-volume histograms (DVHs) of left-sided breast cancer patients undergoing VMAT treatment based solely on their anatomical characteristics. The predicted DVHs could be used to derive patient-specific dose constraints and dose objectives, streamlining the treatment planning process, standardizing the quality of the plans, and personalizing the treatment planning. This study aimed to develop a deep learning-based framework for the prediction of organ-specific dose-volume histograms (DVH) based on structures delineated for left-sided breast cancer treatment. We used a dataset of 249 left-sided breast cancer patients treated with tangential VMAT fields. We extracted delineated structures and dose distributions for each patient and derived slice-by-slice DVHs for planning target volume (PTV) and organs-at-risk. The patients were divided into training (70%, n=174), validation (10%, n=24), and test (20%, n=51) sets. Collected data were used to train a deep learning model for the prediction of the DVHs based on the delineated structures. The developed deep learning model comprised a modified DenseNet architecture followed by a recurrent neural network. In the independent test set (n=51), the point-wise differences in the slice-by-slice DVHs between the clinical and predicted DVHs were small; the mean squared errors were 3.53, 1.58, 2.28, 3.37, and 1.44 [×10-4] for PTV, heart, ipsilateral lung, contralateral lung, and contralateral breast, respectively. With the derived cumulative DVHs, the mean absolute difference±standard deviation of mean doses between the clinical and the predicted DVH were 0.08± 0.04Gy, 0.24± 0.22Gy, 0.73± 0.46Gy, 0.07± 0.06Gy, and 0.14± 0.14Gy for PTV, heart, ipsilateral lung, contralateral lung, and contralateral breast, respectively. The deep learning-based approach enabled automatic and reliable prediction of the DVH based on delineated structures. The predicted DVHs could potentially serve as patient-specific clinical goals used to aid treatment planning and avoid suboptimal plans or to derive optimization objectives and constraints for automated treatment planning.

Analysis of Wedge Angle Variations in the Treatment Planning System Based on Dose Volume Histogram on Ca Mammae Sinistra

Breast cancer ranks first in terms of the highest number of cancers in Indonesia and is one of the first contributors to cancer deaths. According to IARC, radiotherapy is one of the most important modalities in the treatment of breast cancer. Radiotherapy is a type of treatment that uses ionizing radiation to kill cancer cells without damaging surrounding healthy tissue. To obtain an even or homogeneous dose distribution on an uneven skin surface, a wedge is used so that the radiation given to the tumor area is truly optimal and the surrounding healthy tissue receives a minimum dose. This research was carried out by evaluating the Planning Target Volume (PTV) value based on ICRU-83 and dose distribution in Organs at Risk (OAR) based on QUANTEC standards at four different wedge angles, namely 15°, 30°, 45°, and 60°, used the 3D-CRT technique of tangential radiation with a dose of 50 Gy in 25 fractions on 5 left-sided breast cancer patients. The research results showed that the average Homogeneity Index (HI) values for the 15°, 30°, 45° and 60° wedges were 0.286, 0.346, 0.436 and 0.578, respectively. In the left and right lung dose distribution, the results obtained for the 15°, 30°, 45°, and 60° wedge were respectively 2231.4 and 116.2 cGy, 2257.8 and 114.6 cGy, 2141 and 100 cGy, and 2059.4 and 88.8 cGy. For the average dose distribution to the heart, the values obtained at the 15°, 30°, 45°, and 60° wedges were 2005.6 cGy, 2040.4 cGy, 1930.6 cGy, and 1844.4 cGy, respectively. where the average dose received by OAR is still below the limit allowed by QUANTEC. Using a wedge angle of 15° provides a homogeneous dose distribution for the PTV and a wedge angle of 60° provides the lowest dose distribution for the OAR.

Stereotactic body radiotherapy using CyberKnife versus interstitial brachytherapy in accelerated partial breast irradiation on left-sided breast: A comparison of dosimetric characteristics and preliminary clinical results

IntroductionWe compared the dosimetric characteristics of the target and organs at risk (OARs) as well as the preliminary clinical outcomes between two accelerated partial breast irradiation (APBI) techniques. MethodsForty-four patients diagnosed with left-sided early breast cancer who underwent APBI using either interstitial brachytherapy (IB) or stereotactic body radiation therapy (SBRT) with CyberKnife (CK) were retrospectively reviewed. The dosimetric parameters of the target and OARs were compared. Preliminary clinical outcomes, including tumor control and acute toxicity, were analyzed. ResultsTreatment plans with CK demonstrated a better cardiac dose-sparing effect. Radiation doses to the heart at V150cGy for the CK and IB groups were 24.4 % and 60.4 %, respectively (p < 0.001), while the mean heart doses for the CK and IB groups were 107.4 cGy and 204 cGy, respectively (p < 0.001). The heart D1c.c. and the ipsilateral lung received a lower dose in the IB group, without any significant differences. The median follow-up time in the CK and IB groups was 28.6 and 61.3 months, respectively. No patients died from either breast cancer or cardiac events during follow-up. A locoregional recurrence event at the neck occurred in one patient within the IB group. ConclusionsAPBI planned by CK was shown to have a better dose-sparing effect on the heart, as well as better conformity and homogeneity to the target. CK is a non-invasive treatment which showed minimal acute toxicity and promising tumor control.

How Effective is Deep Inspiration Breath Hold in Minimizing Cardiac Doses During Hybrid Radiotherapy Treatment for Left-Sided Breast Cancer with Comprehensive Regional Nodes?

In the context of left breast cancer radiotherapy, long term cardiopulmonary toxicity has been well-documented, significant efforts have been undertaken to mitigate such toxicity by using 4D gating, deep inspiration breath-hold(DIBH) and active breath control(ABC) techniques. To evaluate and compare the cardio-pulmonary radiation doses incurred during postmastectomy radiotherapy (PMRT) in two distinct breathing conditions such as DIBH and Free Breathing (FB), with a specific focus on the left chest wall with comprehensive regional nodal irradiation. A prospective dosimetric study was conducted on 15 patients who received adjuvant loco-regional radiotherapy of chest-wall (CW), supraclavicular fossa(SCF), and internal mammary region(IMC), with or without axilla. Two sets of planning CT scans were taken in DIBH and FB conditions. The dosimetric difference between DIBH CT and FB CT plans analyzed using Wilcoxon signed-rank test, employing SPSS software version 21.0. Comparison of DIBH and FB parameters for target coverage revealed a statistically significant advantage with DIBH in SCF(D95, V90, p<0.017) and IMC(D98, V90 & V95, p<0.03). Dosimetric characteristics of heart and LAD exhibited statistically significant lower doses with DIBH (V20, V25, and Dmean, p<0.001) compared to FB plans. Lung doses were similar with no discernible advantage of one technique over the other. Other OARs such as contralateral breast (p=0.027) and esophagus (p=0.001) received lower doses with the DIBH technique while the spinal cord (p=0.691) and thyroid(p=0.496) showed no significant difference. Maximum heart distance (p= 0.001), central lung distance (p= 0.011) and Haller index (p= 0.001) exhibited statistical significance between the two techniques, whereas chest wall separation showed no significant statistical difference (p=0.629). DIBH demonstrates a substantial reduction in cardiac and LAD doses compared to the FB technique. This study underscores the efficacy of DIBH as a viable strategy for mitigating cardiac and LAD radiation doses in left-sided breast cancer patients undergoing PMRT of chest wall with comprehensive regional nodes.

COMPARATIVE RADIATION DOSIMETRY OF WHOLE BREAST RADIOTHERAPY USING IMRT AND VMAT TECHNIQUES IN LEFT SIDED BREAST CANCER PATIENTS AFTER BREAST CONSERVING SURGERY

Background:The radiotherapy of left sided breast cancers is mandatory and integral part of treatment and challenging because of surrounding critical structures posing increased risk of complications. The main objective of this study was to quantify doses toorgan at risk(OARs) including left lung, heart, contralateral breast, spinal cord, and planning target volume (PTV) using different radiation techniques like Intensity modulated radiation therapy (IMRT)&amp;volumetric modulated arc therapy (VMAT) and comparison of radiation dosimetry. Methods: A prospective study of 30 patients of left sided breast cancer who had undergone Breast Conservative Surgery (BCS) and chemotherapy was done for adjuvant radiation. For every patient radiation planning was done by two different techniques IMRT and VMAT. Then the comparison of radiation dosimetry parameters was done for all the techniques including the parameters like PTV coverage, doses to OAR like heart, left lung, contralateral breast and spinal cord and head of humerus. The Homogenity Index (HI) were calculated. Result: The Mean age of the patient was 46.7 years. When comparing the doses delivered in IMRT and VMAT Technique for left sided breast cancer post breast conservation surgery there was significant difference in PTV Breast and axilla V95 Gy. It was 96.2±1.9% (IMRT) vs 94.8±1.71% (VMAT), (p=0.004). However significant sparing of Organs at Risk was seen. With ipsilateral lung dose mean V5 Gy was 77.86± 9.68% (IMRT) v/s 83.04± 9.86 % (VMAT), (p=0.0446). Also mean V30 Gy was 14.6±4.82% with IMRT vs 16.54±5.86% with VMAT, (p=0.0169). Heart mean dose was 8.8±1.49 Gy with IMRT and 10.98±3.7 Gy with VMAT, (p=0.0227). Further V30 Gy for Heart was 4.61±3.8% with IMRT and 6.72±4.0% with VMAT, (p=0.0132).No significant difference was seen with IMRT and VMAT technique for contralateral lung, contralateral breast and spinal cord. Conclusion: In treatment of patients with radiation with left breast cancer patients post BCS using IMRT and VMAT technique it is seen significant dose reduction with IMRT Technique for ipsilateral lung and Heart as compared to VMAT technique. Significant V95 coverage for PTV Breast and axilla with IMRT as compared to VMAT. Hence in our Study IMRT technique was found to be superior for better sparing of Organ at risk and better PTV coverage.

2522: Optimal pressure of CPAP for reduction mean heart dose in left-sided breast cancer radiotherapy

2522: Optimal pressure of CPAP for reduction mean heart dose in left-sided breast cancer radiotherapy

2571: deep inspiration breath-hold techniques for left-sided breast cancer

2571: deep inspiration breath-hold techniques for left-sided breast cancer

Identification of variables and development of a prediction model for DIBH eligibility in left-sided breast cancer radiotherapy: a prospective cohort study with temporal validation

ObjectiveTo identify variables associated with a patients’ ability to reproducibly hold their breath for deep-inspiration breath-hold (DIBH) radiotherapy (RT) and to develop a predictive model for DIBH eligibility.MethodsThis prospective, single-institution, IRB-approved observational study included women with left-sided breast cancer treated between January 2023 and March 2024. Patients underwent multiple breath-hold sessions over 2–3 consecutive days. DIBH waveform metrics and clinical factors were recorded and analysed. Logistic mixed modelling was used to predict DIBH eligibility, and a temporal validation cohort was used to assess model performance.ResultsIn total, 253 patients were included, with 206 in the model development cohort and 47 in the temporal validation cohort. The final logistic mixed model identified increasing average breath-hold duration (OR, 95% CI: 0.308, 0.104–0.910. p = 0.033) and lower amplitude (OR, 95% CI: 0.737, 0.641–0.848. p < 0.001) as significant predictors of DIBH eligibility. Increasing age was associated with higher odds of being ineligible for DIBH (OR, 95% CI: 1.040, 1.001–1.081. p = 0.044). The model demonstrated good discriminative performance in the validation cohort with an AUC of 80.9% (95% CI: 73.0-88.8).ConclusionThe identification of variables associated with DIBH eligibility and development of a predictive model has the potential to serve as a decision-support tool. Further external validation is required before its integration into routine clinical practice.

Estimating the risk of major adverse cardiac events following radiotherapy for left breast cancer using a modified generalized Lyman normal-tissue complication probability model

BackgroundWe introduced an adapted Lyman normal-tissue complication probability (NTCP) model, incorporating clinical risk factors and censored time-to-event data, to estimate the risk of major adverse cardiac events (MACE) following left breast cancer radiotherapy (RT). Materials and methodsClinical characteristics and MACE data of 1100 women with left-side breast cancer receiving postoperative RT from 2005 to 2017 were retrospectively collected. A modified generalized Lyman NTCP model based on the individual left ventricle (LV) equivalent uniform dose (EUD), accounting for clinical risk factors and censored data, was developed using maximum likelihood estimation. Subgroup analysis was performed for low-comorbidity and high-comorbidity groups. ResultsOver a median follow-up 7.8 years, 64 patients experienced MACE, with higher mean LV dose in affected individuals (4.1 Gy vs. 2.9 Gy). The full model accounting for clinical factors identified D50 = 43.3 Gy, m = 0.59, and n = 0.78 as the best-fit parameters. The threshold dose causing a 50 % probability of MACE was lower in the high-comorbidity group (D50 = 30 Gy) compared to the low-comorbidity group (D50 = 45 Gy). Predictions indicated that restricting LV EUD below 5 Gy yielded a 10-year relative MACE risk less than 1.3 and 1.5 for high-comorbidity and low-comorbidity groups, respectively. ConclusionPatients with comorbidities are more susceptible to cardiac events following breast RT. The proposed modified generalized Lyman model considers nondosimetric risk factors and addresses incomplete follow-up for late complications, offering comprehensive and individualized MACE risk estimates post-RT.

120 Chest Radiographs Predict the Benefit of MHD Reduction Using DIBH in Left Sided Breast Cancer

120 Chest Radiographs Predict the Benefit of MHD Reduction Using DIBH in Left Sided Breast Cancer

Laterality of Radiation Therapy in Breast Cancer is Not Associated With Increased Risk of Coronary Artery Disease in the Contemporary Era

BackgroundExternal beam radiation therapy (EBRT) is a critical component of breast cancer (BC) therapy. Given the improvement in technology in the contemporary era, we hypothesize there is no difference the development of or worsening of existing coronary artery disease (CAD) in patients with BC receiving left vs right sided radiation. MethodsFor the meta-analysis portion of our study, we searched PubMed, Web of Science, and Scopus and included studies from January 1999 to September 2022. CAD was identified using a homogenous metric across multiple studies included. We computed the risk ratio (RR) for included studies using a random effects model. For the institutional cohort portion of our study, we selected high cardiovascular risk patients diagnosed with BC between 2010-2022 if they met our inclusion criteria. We performed a Cox proportional hazards model with stepwise adjustment. ResultsA pooled random effects model with 9 studies showed that patients with left-sided BC receiving EBRT had a 10% increased risk of CAD when compared to patients with right-sided BC receiving EBRT (RR: 1.10, 95% CI: 1.02 - 1.18, p = 0.01). However, subgroup analysis of 6 studies that included patients diagnosed after 1980 did not show a significant difference in CAD based on BC laterality (RR: 1.07, 95% CI: 0.95 – 1.20, p = 0.27). For the institutional cohort portion of the study, we found that patients with left-sided BC who received EBRT did not have a significantly higher risk for CAD when compared to their right-sided counterparts (HR = 0.73, 95% CI: 0.34 - 1.54, p = 0.402). ConclusionOur study suggests a historical trend of increased CAD in BC patients receiving left-sided EBRT. Data from patients diagnosed after 2010 in our institutional cohort did not show a significant difference, emphasizing that modern EBRT regimens are safe, and laterality of BC does not affect CAD outcomes in the short term after a breast cancer diagnosis.

Proton therapy reduces the effective dose to immune cells in breast cancer patients.

The effective dose to circulating immune cells (EDIC) is associated with survival in lung and esophageal cancer patients. This study aimed to evaluate the benefit of intensity-modulated proton therapy (IMPT) for EDIC reduction as compared to volumetric modulated arc therapy (VMAT) in patients with locally advanced breast cancer (BC). Ten BC patients treated with locoregional VMAT after breast-conserving surgery were included. Mean dose to the heart (MHD), lungs (MLD), and liver (MlD), as well as the integral dose to the body (ITD), were retrieved, and we calculated EDIC as 0.12 × MLD + 0.08 × MHD + 0.15 × 0.85 × √(n/45) × MlD + (0.45 + 0.35 × 0.85 × √(n/45)) × ITD/(62 × 103), where n is the number of fractions. EDIC was compared between VMAT and IMPT plans. Median EDIC was reduced from 3.37 Gy (range: 2.53-5.99) with VMAT to 2.13 Gy (1.31-3.77) with IMPT (p < 0.01). For left-sided BC patients, EDIC was reduced from 3.15 Gy (2.53-3.78) with VMAT to 1.65 Gy (1.31-3.77) with IMPT (p < 0.01). For right-sided BC patients, EDIC was reduced from 5.60 Gy (5.06-5.99) with VMAT to 3.38 Gy (3.10-3.77) with IMPT (p < 0.01). Right-sided BC patients had ahigher EDIC irrespective of the technique. Integral dose reduction was the main driver of EDIC reduction with IMPT and was associated with lung sparing for left-sided BC patients or liver sparing for right-sided BC patients. IMPT significantly reduced EDIC in BC patients undergoing locoregional adjuvant radiotherapy. Integral total dose reduction, associated with improved lung sparing in left-sided BC patients or liver sparing in right-sided BC patients, mainly drove EDIC reduction with IMPT. The emergence of dynamic models taking into account the circulatory kinetics of immune cells may improve the accuracy of the estimate of the dose received by the immune system compared to calculation of the EDIC, which is based solely on static dosimetric data.