A survey of cancer patients' interest in undertaking exercise to promote relaxation during radiotherapy for breast cancer and metastatic cancer.

BACKGROUND: Approximately 25-50% of patients undergoing radiotherapy (RT) experience psychological distress and anxiety, which can detrimentally affect both their quality of life and treatment outcomes. While previous research has demonstrated that relaxation exercises can enhance the tolerability of RT and alleviate associated stress and anxiety, the specific needs for such therapies in radiation oncology remain under-explored. This study aims to investigate the demand for and preferences toward relaxation exercises among radiotherapy patients, addressing a critical gap in patient-centered care. METHODS: A prospective pseudonymized survey study using a one-time paper-based questionnaire was conducted from 2022 to 2023 among patients undergoing curative-intent RT for breast cancer or patients undergoing palliative RT for bone metastases. Patients were asked in a 11-item questionnaire about their anxiety, pre-existing practice of relaxation exercises/interventions, their interest in relaxation exercises, and preferences on the type and format of instruction. Data were analyzed descriptively. RESULTS: 100 patients (74 female and 26 male) responded, of whom 68 received curative-intent adjuvant RT and 32 palliative RT. Median age was 62 years. 78% of patients indicated a desire to be actively involved in their radiotherapy, but only 27% had used relaxation exercises prior to RT. 44.8% of both curatively and palliatively treated patients who wanted to be actively involved in their therapy desired to learn how to best relax. 56.4% of respondents were willing to spend extra time learning offered exercises. CONCLUSION: The survey indicates that patients undergoing RT, both for curative or palliative intent, desire relaxation exercises to relieve stress and anxiety from RT. It is therefore important to assess the need for relaxation interventions in individual patients and to develop suitable programs or collaborate with other healthcare professionals to meet these needs.

Survival benefits of postoperative radiotherapy in patients with cT1 - 2N1M0 breast cancer after neoadjuvant chemotherapy: a SEER-based population study.

BACKGROUND: Whether patients with cT1 - 2N1M0 breast cancer can benefit from postoperative radiotherapy (RT) after receiving neoadjuvant chemotherapy (NAC) has been controversial. Therefore, the purpose of this study was to explore whether postoperative RT can benefit this group of patients in terms of survival. METHODS: We used Surveillance, Epidemiology, and End Results (SEER) data to conduct a retrospective review of women with cT1 - 2N1M0 breast cancer diagnosed between 20 and 80 years of age who received NAC between 2010 and 2015. Our study compared the impact of postoperative RT on overall survival (OS) and cancer-specific survival (CSS) in breast cancer patients using propensity score matching (PSM) and performed subgroup analysis. RESULTS: This study finally included 1092 cT1 - 2N1M0 breast cancer patients. Regardless of the patient's PSM status, postoperative RT was significantly associated with OS of cT1-2N1M0 breast cancer patients who received NAC. Specifically, the 10-year OS rate was 78.7% before PSM matching, compared with 71.1% in patients who did not receive postoperative RT, and the difference was more significant after PSM matching, which was 83.1% and 71.1% respectively. However, postoperative RT did not significantly benefit CSS in patients with cT1 - 2N1M0 breast cancer who received NAC. The 10-year CSS rate was 81.4% VS 76.2% (P = 0.085) before PSM matching and 85.8% VS 76.2%(P = 0.076) after matching. Due to the intersection of OS and CSS curves, this restricted mean survival time (RMST) method was chosen as a supplement. After 60 months, the OS difference in RMST between the postoperative RT group and the non-radiotherapy (noRT) group was 7.37 months (95%CI: 0.54-14.21; P = 0.034), and the CSS difference was 5.18 months (95%CI: -1.31-11.68; P = 0.118). Subgroup analysis found that in patients with right-sided breast cancer, postoperative RT improved the patient's OS (HR = 0.45, 95%CI: 0.21-0.95, P = 0.037) and CSS (HR = 0.42, 95%CI: 0.18-0.98, P = 0.045). CONCLUSIONS: Our results showed that additional postoperative RT improved the OS of cT1 - 2N1M0 breast cancer patients who received NAC, but failed to improve their CSS. It is worth noting that in the subgroup analysis of patients with right-sided breast cancer, we observed significant improvements in OS and CSS. And further prospective studies are still needed to verify the effect of postoperative RT in different subgroups.

Biological effects of intraoperative radiation therapy: histopathological changes and immunomodulation in breast cancer patients.

Introduction: Intraoperative radiation therapy (IORT) delivers a single accelerated radiation dose to the breast tumor bed during breast-conserving surgery (BCS). The synergistic biologic effects of simultaneous surgery and radiation remain unclear. This study explores the cellular and molecular changes induced by IORT in the tumor microenvironment and its impact on the immune response modulation. Methods: Patients with hormone receptor (HR)-positive/HER2-negative, ductal carcinoma in situ (DCIS), or early-stage invasive breast carcinoma undergoing BCS with margin re-excision were included. Histopathological evaluation and RNA-sequencing in the re-excision tissue were compared between patients with IORT (n=11) vs. non-IORT (n=11). Results: Squamous metaplasia with atypia was exclusively identified in IORT specimens (63.6%, p=0.004), mimicking DCIS. We then identified 1,662 differentially expressed genes (875 upregulated and 787 downregulated) between IORT and non-IORT samples. Gene ontology analyses showed that IORT was associated with the enrichment of several immune response pathways, such as inflammatory response, granulocyte activation, and T-cell activation (p<0.001). When only considering normal tissue from both cohorts, IORT was associated with intrinsic apoptotic signaling, response to gamma radiation, and positive regulation of programmed cell death (p<0.001). Using the xCell algorithm, we inferred a higher abundance of γδ T-cells, dendritic cells, and monocytes in the IORT samples. Conclusion: IORT induces histological changes, including squamous metaplasia with atypia, and elicits molecular alterations associated with immune response and intrinsic apoptotic pathways. The increased abundance of immune-related components in breast tissue exposed to IORT suggests a potential shift towards active immunogenicity, particularly immune-desert tumors like HR-positive/HER2-negative breast cancer.

Neoadjuvant radiotherapy in ER+, HER2+, and triple-negative -specific breast cancer based humanized tumor mice enhances anti-PD-L1 treatment efficacy.

Pre-operative radiation therapy is not currently integrated into the treatment protocols for breast cancer. However, transforming immunological "cold" breast cancers by neoadjuvant irradiation into their "hot" variants is supposed to elicit an endogenous tumor immune defense and, thus, enhance immunotherapy efficiency. We investigated cellular and immunological effects of sub-lethal, neoadjuvant irradiation of ER pos., HER2 pos., and triple-negative breast cancer subtypes in-vitro and in-vivo in humanized tumor mice (HTM). This mouse model is characterized by a human-like immune system and therefore facilitates detailed analysis of the mechanisms and efficiency of neoadjuvant, irradiation-induced "in-situ vaccination", especially in the context of concurrently applied checkpoint therapy. Similar to clinical appearances, we observed a gradually increased immunogenicity from the luminal over the HER2-pos. to the triple negative subtype in HTM indicated by an increasing immune cell infiltration into the tumor tissue. Anti-PD-L1 therapy divided the HER2-pos. and triple negative HTM groups into responder and non-responder, while the luminal HTMs were basically irresponsive. Irradiation alone was effective in the HER2-pos. and luminal subtype-specific HTM and was supportive for overcoming irresponsiveness to single anti-PD-L1 treatment. The treatment success correlated with a significantly increased T cell proportion and PD-1 expression in the spleen. In all subtype-specific HTM combination therapy proved most effective in diminishing tumor growth, enhancing the immune response, and converted non-responder into responder during anti-PD-L1 therapy. In HTM, neoadjuvant irradiation reinforced anti-PD-L1 checkpoint treatment of breast cancer in a subtype -specific manner. According to the "bench to bedside" principle, this study offers a vital foundation for clinical translating the use of neoadjuvant irradiation in the context of checkpoint therapy.

Surface dose measurement and comparison between TLD and OSLD during modified re constructive mastectomy irradiation.

Radiotherapy (RT) is one of the major treatment modalities among surgery and chemotherapy for carcinoma breast. The surface dose study of modified reconstructive constructive Mastectomy (MRM) breast is important due to the heterogeneity in the body contour and the conventional treatment angle to save the lungs and heart from the radiation. These angular entries of radiation beam cause an unpredictable dose deposition on the body surface, which has to be monitored. Thermoluminescent dosimeter (TLD) or optically stimulated luminescent dosimeter (nano OSLD) are commonly preferable dosimeters for this purpose. The surface dose response of TLD and nano OSLD during MRM irradiation has been compared with the predicted dose from the treatment planning system (TPS). The study monitored 100 MRM patients by employing a total 500 dosimeters consisting of TLD (n = 250) and nano OSLD (n = 250), during irradiation from an Elekta Versa HD 6 MV Linear accelerator. The study observed a variance of 3.9% in the dose measurements for TLD and 3.2% for nano OSLD from the planned surface dose, with a median percentage dose of 44.02 for nano OSLD and 40.30 for TLD (p value 0.01). There was no discernible evidence of variation in dose measurements attributable to differences in field size or from patient to patient. Additionally, no variation was observed in dose measurements when comparing the placement of the dosimeter from central to off-centre positions. In comparison, a minor difference in dose measurements were noted between TLD and nano OSLD, The study's outcomes support the applicability of both TLD and nano OSLD as effective dosimeters during MRM breast irradiation for surface dose evaluation.

Assessment of Radiation Induced Pneumonitis and Pericarditis in Patients Undergoing Breast Conservative Treatment Using Hypofractionated Simultaneous Integrated Boost Technique.

INTRODUCTION: To determine the proportion of radiationinduced pneumonitis and pericarditis in patients who have received Hypo-fractionated Radiation along with simultaneous integrated boost technique after breast conservative surgery using a prospective observational study from a tertiary hospital. MATERIALS & METHODS: The incidence of radiationinduced pneumonitis and pericarditis was evaluated in all adult patients with biopsy-proven early-stage unilateral breast cancer who underwent breast-conserving surgery followed by hypo-fractionated radiation with a simultaneous integrated boost technique. Baseline assessments including a six-minute walk test, highresolution computed tomography (HRCT), pulmonary function tests (PFTs), electrocardiography (ECG) and echocardiography (ECHO) were performed. At three months post-radiation treatment, patients underwent follow-up assessments with a six-minute walk test, ECG and ECHO. At six months post-radiation treatment, patients underwent further assessments with a six-minute walk test, ECG, ECHO, PFTs, and HRCT of the thorax. Data analysis was performed using SPSS version 19. RESULTS: Our study investigated the incidence of acute radiation-induced pneumonitis and pericarditis in patients treated with hypofractionated VMAT-SIB technique in 20 eligible early breast cancer patients. The study found that the technique is feasible and achieves encouraging dosimetric parameters, including well achieved ipsilateral lung and heart doses. The reduced treatment time of 3-4 weeks compared to the previous 6-7 weeks with sequential boost was also found to be desirable in resource-constrained settings. The incidence of acute radiation pneumonitis and pericarditis was acceptable and comparable to existing data, with 90% of patients experiencing grade 1 radiation pneumonitis according to CTCAE v5.0. Post-treatment pulmonary function tests showed significant changes, particularly in patients who had received neoadjuvant chemotherapy and nodal irradiation. The six-minute walk test and Borg scale also showed a significant positive correlation with pulmonary function tests. There was no significant pericarditis during the follow-up. The study proposes that the hypofractionated radiotherapy using VMAT-SIB is a suitable alternative to conventional fractionation, with acceptable acute toxicities, but longer follow-up is required to assess the impact on late toxicities. CONCLUSION: Our research has shown that hypofractionated adjuvant radiotherapy with SIB is a safe and feasible treatment for patients with early breast cancer. This treatment method doesn't pose any significant short-term risks to the lungs or heart, and the SIB technique provides better coverage, conformity and sparing of organs at risk. Additionally, patients have reported positive cosmetic outcomes with this treatment. However, to make more accurate conclusions, we need to conduct further studies with larger sample sizes and longer follow-up periods to evaluate the potential longterm side effects of this treatment using VMAT in whole breast radiation.

[Prevention of radiotherapy-related cardiotoxicity : benefits of a specialized cardio-oncologic assessment and follow-up]. / Prévention de la cardio-toxicité de la radiothérapie : apport de la prise en charge cardio-oncologique.

To accept the toxic side effects of any treatment, whether medical, surgical or radiotherapeutic, cannot be avoided but implies to evaluate them taking into account the severity and prognosis of the disease that is concerned. Screening, preventing and treatment of these side effects are an integral aspect of the treatment of cancers. We will here review the contribution of the cardio-oncology, a recently emerged medical specialty. Cardiac irradiation cannot be avoided when treating several cancers, most frequently left sided breast cancer. As soon as radiotherapy is considered, it is of prime importance to evaluate each patient's risk factors and to handle them. If technical progresses have led to the complete disappearance of acute side effects of radiotherapy, this is not true for the delayed ones that may occur many years after the irradiation. Hence the need for «red flags¼ and for a systematic follow-up. Cardiac complications of left breast irradiation concern all aspects of cardiology: diseases of cardiac rhythm, valvulopathies, heart failure, coronary and pericardial disorders.

Admettre les effets secondaires d'un traitement, qu'il soit médical, chirurgical ou radiothérapique, est inévitable, mais impose de les évaluer en intégrant la gravité de l'affection pour laquelle ils sont prescrits. Leur dépistage, leur prévention et leur prise en charge font partie intégrante du traitement d'un cancer. Dans cette revue, nous ferons la synthèse de l'apport à cette démarche d'une discipline récente, la cardio-oncologie. L'irradiation cardiaque est incontournable lors du traitement de plusieurs cancers au premier rang desquels le cancer du sein gauche. Dès qu'elle est envisagée, il est essentiel d'évaluer les facteurs de risque de chaque patient et d'organiser leur prise en charge éventuelle. En effet, si les progrès techniques ont permis la disparition des complications cardiaques aiguës de la radiothérapie, ce n'est encore pas le cas des complications différées qui peuvent survenir de nombreuses années après l'irradiation. D'où la nécessité de «drapeaux rouges¼ et d'un suivi régulier systématique. Ces complications, rarement isolées, concernent tous les aspects de la cardiologie : troubles du rythme, valvulopathies, insuffisance cardiaque, maladies coronaires et atteintes péricardiques.

Role of periodic irradiation and incident beam radius for plasmonic photothermal therapy of subsurface tumors.

Plasmonic photothermal therapy (PPTT) is a potential technique to treat tumors selectively. However, during PPTT, issue of high temperature region and damage to the surrounding healthy is still need to be resolved. Also, treatment of deeper tumors non-invasively is a challenge for PPTT. In this paper, the effect of periodic irradiation and incident beam radius (relative to tumor size) for various gold nanorods (GNRs) concentrations is investigated to avoid much higher temperatures region with limiting thermal damage to the surrounding healthy tissue during PPTT of subsurface breast tumors located at various depths. Lattice Boltzmann method is used to solve Pennes' bioheat model to compute the resulting photothermal temperatures for the subsurface tumor embedded with GNRs subjected to broadband near infrared radiation of intensity 1 W/cm2. Computation revealed that low GNRs concentration leads to uniform internal heat generation than higher GNRs concentrations. The results show that deeper tumors, due to attenuation of incident radiation, show low temperature rise than shallower tumors. For shallower tumors situated 3 mm deep, 70% irradiation period resulted in around 20 °C reduction (110 °C-90 °C) of maximum temperature than that with the continuous irradiation. Moreover, 70% beam radius (i.e., beam radius as 70% of the tumor radius) causes less thermal damage to the nearby healthy tissue than 100% beam radius (i.e., beam radius equal to the tumor radius). The thermal damage within the healthy tissue is minimized to the 1 mm in radial direction and 3 mm in axial direction for 70% beam radius with 70% irradiation period. Overall, periodic heating and changing beam radius of the incident irradiation lead to reduce high temperature and limit healthy tissue damage. Hence, discussed results are useful for selection of the irradiation parameters for PPTT of sub-surface tumors.

Cosmetic considerations after breast cancer treatment.

Treatments for breast cancer can have an array of adverse effects, including hair loss, scarring, and irritated skin. These physical outcomes can, in turn, lead to body image concerns, anxiety, and depression. Fortunately, there is growing evidence that certain cosmetic therapies can improve patient self-image. Here we review various cosmetic treatment options including hair camouflage, eyebrow and eyelash camouflage, treatments for hirsutism, nipple and areola tattooing, post-mastectomy scar tattooing, treatments for dry skin/xerosis, removal of post-radiation telangiectasias, and lightening of post-radiation hyperpigmentation. For each patient concern, we report potential procedures, clinical evidence of impact on quality of life, special considerations, and safety concerns. This article aims to equip dermatologists with resources so that they may effectively counsel breast cancer survivors who express treatment-related cosmetic concerns.

Personalizing Locoregional Therapy in Patients With Breast Cancer in 2024: Tailoring Axillary Surgery, Escalating Lymphatic Surgery, and Implementing Evidence-Based Hypofractionated Radiotherapy.

The management of axillary lymph nodes in breast cancer is continually evolving. Recent data now support omitting axillary lymph node dissection (ALND) in most patients with metastases in up to two sentinel lymph nodes (SLNs) during upfront surgery and those with residual isolated tumor cells after neoadjuvant chemotherapy (NACT). In the upfront surgery setting, ALND is still indicated, however, in patients with clinically node-positive breast cancer or more than two positive SLNs and, after NACT, in case of residual micrometastases and macrometastases. Omission of the sentinel lymph node biopsy (SLNB) can be considered in many postmenopausal patients with small luminal breast cancer, particularly when axillary ultrasound is negative. Several randomized controlled trials (RCTs) are currently aiming at eliminating the remaining indications for ALND and also establishing omission of SLNB in a broader patient population. The movement to deescalate axillary staging is in part because of the association between ALND and lymphedema, which is swelling of an extremity because of lymphatic damage and obstructed lymphatic drainage. To reduce the risk of developing this condition, patients undergoing ALND can undergo reverse mapping of the axilla and immediate reconstruction or bypass of the lymphatics from the involved extremity. Decongestion and compression are the foundation of conservative treatment for established lymphedema, while lymphovenous bypass and lymph node transfer are surgical procedures to address the physiologic dysfunction. Radiotherapy is an essential component of breast locoregional therapy: more than three decades of radiation research has optimized treatment according to patient's risk of local recurrence while substantially reducing the number of treatment visits. High-quality RCTs have shown the efficacy and safety of hypofractionation-more than 2Gy radiation dose per treatment (fraction)-significantly reducing the burden of radiotherapy treatment for many patients with breast cancer. In 2024, guidelines recommend no more than 15-16 fractions for whole-breast and nodal radiotherapy, with some recommending five fractions for whole-breast radiotherapy. In addition, simultaneous integrated boost (SIB) has been shown to be noninferior to sequential boost with regards to ipsilateral breast tumor recurrence with similar or reduced long-term side effects, also reducing overall treatment length. Further RCTs are underway investigating other indications for five fractions, including SIB and regional node irradiation, such that, in future, it may be possible for the majority of breast radiotherapy patients to be treated with a 1-week course. This manuscript serves to outline the latest updates on axillary surgical staging, lymphatic surgery, and evidence-based radiotherapy in the treatment of breast cancer.

Hypofractionated radiotherapy with simultaneous tumor bed boost (Hi-RISE) in breast cancer patients receiving upfront breast-conserving surgery: study protocol for a phase III randomized controlled trial.

BACKGROUND: The effectiveness and safety of moderately hypofractionated radiotherapy (HFRT) in patients undergoing breast-conserving surgery (BCS) has been demonstrated in several pivotal randomized trials. However, the feasibility of applying simultaneous integrated boost (SIB) to the tumor bed and regional node irradiation (RNI) using modern radiotherapy techniques with HFRT needs further evaluation. METHODS: This prospective, multi-center, randomized controlled, non-inferiority phase III trial aims to determine the non-inferiority of HFRT combined with SIB (HFRTsib) compared with conventional fractionated radiotherapy with sequential boost (CFRTseq) in terms of five-year locoregional control rate in breast cancer patients undergoing upfront BCS. A total of 2904 participants will be recruited and randomized in a 1:1 ratio into the HFRTsib and CFRTseq groups. All patients will receive whole breast irradiation, and those with positive axillary nodes will receive additional RNI, including internal mammary irradiation. The prescribed dose for the HFRTsib group will be 40 Gy in 15 fractions, combined with a SIB of 48 Gy in 15 fractions to the tumor bed. The CFRTseq group will receive 50 Gy in 25 fractions, with a sequential boost of 10 Gy in 5 fractions to the tumor bed. DISCUSSION: This trial intends to assess the effectiveness and safety of SIB combined with HFRT in early breast cancer patients following BCS. The primary endpoint is locoregional control, and the results of this trial are expected to offer crucial evidence for utilizing HFRT in breast cancer patients after BCS. TRIAL REGISTRATION: This trial was registered at ClincalTrials.gov (NCT04025164) on July 18, 2019.

Investigating Radiotherapy Effects on PD-L1 Expression in Circulating Tumor Cells: An Exploratory Study.

INTRODUCTION: Circulating tumor cells (CTCs) and Programmed death-ligand 1 (PD-L1) play pivotal roles in cancer biology and therapy response. This exploratory study aimed to elucidate the influence of neoadjuvant radiotherapy on PD-L1 expression in tumor tissues and CTCs of patients with inoperable locally advanced breast cancer. METHODS: We conducted a prospective cohort study at Universitas Andalas Hospital Padang from January to December 2022 with 27 patients. Biopsies and blood draws were executed before and after the tenth fractions of neoadjuvant radiotherapy. Following radiotherapy, CTCs were isolated using magnetic beads enrichment, followed by an RT-PCR analysis for PD-L1 expression. Correlations between PD-L1 expression and tumor response, evaluated via local response and RECIST criteria before and after radiotherapy breast CT scan, were examined using Fisher's exact and chi-square tests. RESULTS: Our data revealed no significant alterations in PD-L1 expression in either tumor tissues or CTCs during radiotherapy (p=0.848 for tissue, p=0.548 for CTCs). Notably, PD-L1 expression in tumor tissue before treatment was significantly associated with RECIST (p=0.021), while other correlations with local response and RECIST were not statistically significant. CONCLUSION: The study implies radiotherapy may not significantly influence PD-L1 expression in tumor tissue and CTCs. However, pre-treatment PD-L1 expression in tumor tissue correlates with RECIST criteria. These findings highlight the need for additional, comprehensive studies to elucidate further the interplay between PD-L1, CTCs, and radiotherapy response.

Dosimetry and Biochemical Comparison of Early Radiation-Induced Lung Toxicity in Breast Cancer Patients Treated with 3D-CRT and IMRT: the Role of Serum Interleukin-6 and Pulmonary Surfactant Protein-D.

BACKGROUND: Radiation-induced lung disease is a potentially fatal, dose-limiting toxicity commonly seen after radiotherapy of thoracic malignancies, including breast cancer. AIM: To evaluate and compare the early lung toxicity induced by 3D-CRT and IMRT radiotherapy treatment modalities in breast cancer female patients using biochemical, dosimetry and clinical data. SUBJECTS AND METHODS: this study included 15 normal healthy controls, 15 breast cancer patients treated with IMRT, and 15 breast cancer patients treated with 3D-CRT. One blood sample was obtained from the control group and 3 blood samples were withdrawn from cases before RT, after RT and after 3 months of RT. RESULT: IMRT delivered higher radiation dose to the breast tumor and lower doses to the lung as an organ at risk. There was a non-significant increase in the serum levels of IL-6 before IMRT and 3D-CRT compared with its levels in the control group. There were significant increases in serum levels of IL-6 after RT (IMRT and 3DCRT) compared with its levels before RT. There was a non-significant decrease in the serum levels of IL-6 after 3 months of RT (IMRT and 3D-CRT) compared with its serum levels immediately after RT. There was a non-significant increase in the serum levels of SP-D before RT (IMRT and 3D-CRT) compared with its levels in the control group. There were significant-increases in serum levels of SP-D after RT (IMRT and 3D-CRT) compared with its levels before RT. There was a non-significant decrease in the serum levels of SP-D after 3 months of radiotherapy (IMRT and 3D-CRT) compared with its serum levels immediately after RT. CONCLUSION: serum of levels IL-6 and SP-D can be used to diagnose the occurrence of early lung toxicity due to radiotherapy and the rate of recovery from radiation pneumonitis is apparent in case of IMRT than 3D-CRT.

Uncertainty estimation- and attention-based semi-supervised models for automatically delineate clinical target volume in CBCT images of breast cancer.

OBJECTIVES: Accurate segmentation of the clinical target volume (CTV) of CBCT images can observe the changes of CTV during patients' radiotherapy, and lay a foundation for the subsequent implementation of adaptive radiotherapy (ART). However, segmentation is challenging due to the poor quality of CBCT images and difficulty in obtaining target volumes. An uncertainty estimation- and attention-based semi-supervised model called residual convolutional block attention-uncertainty aware mean teacher (RCBA-UAMT) was proposed to delineate the CTV in cone-beam computed tomography (CBCT) images of breast cancer automatically. METHODS: A total of 60 patients who undergone radiotherapy after breast-conserving surgery were enrolled in this study, which involved 60 planning CTs and 380 CBCTs. RCBA-UAMT was proposed by integrating residual and attention modules in the backbone network 3D UNet. The attention module can adjust channel and spatial weights of the extracted image features. The proposed design can train the model and segment CBCT images with a small amount of labeled data (5%, 10%, and 20%) and a large amount of unlabeled data. Four types of evaluation metrics, namely, dice similarity coefficient (DSC), Jaccard, average surface distance (ASD), and 95% Hausdorff distance (95HD), are used to assess the model segmentation performance quantitatively. RESULTS: The proposed method achieved average DSC, Jaccard, 95HD, and ASD of 82%, 70%, 8.93, and 1.49 mm for CTV delineation on CBCT images of breast cancer, respectively. Compared with the three classical methods of mean teacher, uncertainty-aware mean-teacher and uncertainty rectified pyramid consistency, DSC and Jaccard increased by 7.89-9.33% and 14.75-16.67%, respectively, while 95HD and ASD decreased by 33.16-67.81% and 36.05-75.57%, respectively. The comparative experiment results of the labeled data with different proportions (5%, 10% and 20%) showed significant differences in the DSC, Jaccard, and 95HD evaluation indexes in the labeled data with 5% versus 10% and 5% versus 20%. Moreover, no significant differences were observed in the labeled data with 10% versus 20% among all evaluation indexes. Therefore, we can use only 10% labeled data to achieve the experimental objective. CONCLUSIONS: Using the proposed RCBA-UAMT, the CTV of breast cancer CBCT images can be delineated reliably with a small amount of labeled data. These delineated images can be used to observe the changes in CTV and lay the foundation for the follow-up implementation of ART.

Quantify the Effect of Air Gap Errors on Skin Dose for Breast Cancer Radiotherapy.

Purpose: Determining the impact of air gap errors on the skin dose in postoperative breast cancer radiotherapy under dynamic intensity-modulated radiation therapy (IMRT) techniques. Methods: This was a retrospective study that involved 55 patients who underwent postoperative radiotherapy following modified radical mastectomy. All plans employed tangential IMRT, with a prescription dose of 50 Gy, and bolus added solely to the chest wall. Simulated air gap depth errors of 2 mm, 3 mm, and 5 mm were introduced at depression or inframammary fold areas on the skin, resulting in the creation of air gaps named Air2, Air3, and Air5. Utilizing a multivariable GEE, the average dose (Dmean) of the local skin was determined to evaluate its relationship with air gap volume and the lateral beam's average angle (AALB). Additionally, an analysis was conducted on the impact of gaps on local skin. Results: When simulating an air gap depth error of 2 mm, the average Dmean in plan2 increased by 0.46 Gy compared to the initial plan (planO) (p < .001). For the 3-mm air gap, the average Dmean of plan3 was 0.51 Gy higher than that of planO (p < .001). When simulating the air gap as 5 mm, the average Dmean of plan5 significantly increased by 0.59 Gy compared to planO (p < .001). The TCP results showed a similar trend to those of Dmean. As the depth of air gap error increases, NTCP values also gradually rise. The linear regression of the multivariable GEE equation indicates that the volume of air gaps and the AALB are strong predictors of Dmean. Conclusion: With small irregular air gap errors simulated in 55 patients, the values of skin's Dmean, TCP, and NTCP increased. A multivariable linear GEE regression model may effectively explain the impact of air gap volume and AALB on the local skin.