Journal of Radiation Research最新文献

This study aimed to investigate the safety of combining radium-223 chloride (Ra-223) therapy with external beam radiation therapy (EBRT) for patients with multiple bone metastases from castration-resistant prostate cancer (CRPC), including lesions requiring urgent treatment such as those causing neurological symptoms due to spinal cord compression. We retrospectively analyzed data from patients with CRPC and bone metastases treated with Ra-223 therapy at our hospital between September 1, 2018, and December 31, 2023. Adverse events were evaluated using the Common Terminology Criteria for Adverse Events version 4.0. Of the 23 patients referred, data from 17 were included; 8 received concurrent Ra-223 therapy and EBRT, whereas others received only Ra-223 therapy. The median follow-up period was 20 months. Grade (G) 2 or higher adverse events occurred in seven patients (41.2%), and G 3 or higher in 2 (11.7%). None of the patients who received EBRT with fields involving the gastrointestinal tract experienced diarrhea, constipation, bleeding, perforation, or obstruction. Ra-223 therapy with EBRT did not increase adverse events compared with studies of Ra-223 therapy without EBRT. One case of G 5 Pneumocystis carinii pneumonia, likely because of steroid use for neurological symptoms and the patient's underlying diabetes mellitus, was noted. The effects of EBRT cannot be entirely excluded, so minimizing field size and dose is recommended when combining Ra-223 therapy and EBRT. Our findings indicate that concurrent Ra-223 therapy and EBRT could be safe for managing patients with symptomatic bone metastases and castration-resistant prostate cancer who require specialized treatment, provided sufficient attention is given to the field and the prescribed dose.

This study aimed to evaluate the prognostic value of pre-treatment blood cell counts in patients with brain metastasis (BM) from non-small cell lung cancer (NSCLC) who were treated using linear accelerator (linac)-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator. Between January 2011 and November 2022, 271 consecutive patients underwent linac-based SRS/fSRT for BM from NSCLC. Thirty patients with insufficient blood test data during this period were excluded from this analysis. Thirty-five patients with steroid intake at the time point of the blood test and 18 patients with higher C-reactive protein were excluded. Thus, 188 patients were eventually enrolled in this study. The median follow-up period after SRS/fSRT was 21 months (range: 0-121 months), and the median survival time after SRS/fSRT was 19 months. Neutrophil-lymphocyte ratio ≥ 1.90, lymphocyte-monocyte ratio ≤ 1.67 and systemic inflammation response index (SIRI) ≥ 2.95 were unfavorable predictors of prognosis for patients who underwent SRS/fSRT for BM from NSCLC. Cox proportional-hazard multivariate analysis revealed that the SIRI was independent prognostic factors for increased risk of death. Thus, simple, less expensive, and routinely performed pre-treatment blood cell count measurements such as SIRI can predict the overall survival of patients treated with SRS/fSRT for BM from NSCLC.

Postoperative chemoradiotherapy (POCRT) is the standard treatment for patients with head and neck squamous cell carcinoma (HNSCC) with high-risk features (positive microscopic margins and/or extranodal extensions). We hypothesized that dose escalation using hyperfractionation in intensity-modulated radiotherapy (HF-IMRT) improves POCRT outcomes; however, no prospective trial has assessed the feasibility of POCRT in HF. Therefore, we evaluated the feasibility of POCRT using HF-IMRT. HNSCC patients with positive microscopic margins and/or extranodal extension following surgery were included. HF-IMRT (73.6 Gy in 64 fractions twice daily) was administered along with cisplatin at 40 mg/m2 once a week for seven cycles during radiotherapy. The primary endpoint was the proportion of patients who completed treatment, which included the planned radiotherapy and the administration of ≥200 mg/m2 of cisplatin. Feasibility was defined as the proportion of patients who completed treatment >60% using a one-sided binomial test. Ten patients were registered between October 2021 and April 2023. One patient was excluded because of tumor recurrence before POCRT. The median follow-up time was 18.2 months, and the proportion of patients who completed treatment was 88.9%. The median total dose of cisplatin was 240 mg/m2. The percentage of patients with grade 3 acute non-hematological adverse events was 77.8%. No patient experienced grade 4 or higher acute adverse events or grade 3 or higher late adverse events. POCRT using HF-IMRT is feasible for achieving adequate cisplatin doses and safe radiotherapy in patients with HNSCC.

Lung cancer is the most prevalent cancer worldwide, and radon exposure is ranked as the second risk factor after cigarette smoking. It has been reported that radon induces deoxyribonucleic acid damage and oxidative stress in cells. However, the protein profile and potential biomarkers for early detection of radon-induced lung cancer remain unknown. In this study, we aimed to investigate the effects of intermittent high-dose radon exposure on lung epithelial cells, analyze protein profiles and identify potential biomarkers for diagnosis of radon-related lung cancer. Human lung epithelial cells (A549) were exposed to radon (1000 Bq/m3) for 30 min daily for 7 days. Cell viability was measured using the WST-1 assay, and liquid chromatography-mass spectrometry proteomic analysis was performed. Differentially expressed proteins and gene ontology (GO) enrichment were analyzed. Our findings showed that intermittent high-radon exposure reduced A549 cell viability over time. Proteomic analysis identified proteins associated with stressed-induced apoptosis, mitochondrial adaptation, nuclear integrity and lysosomal degradation. These proteins are related to catabolism, stress response, gene expression and metabolic processes in the biological process of GO analysis. We highlighted specific proteins, including AKR1B1, CDK2, DAPK1, PRDX1 and ALHD2 with potential as biomarkers for radon-related lung cancer. In summary, intermittent high-dose radon exposure affects cellular adaptions of lung epithelial cells including stress-induced apoptosis, mitochondrial dysfunctions and immune regulation. The identified proteins may serve as diagnostic biomarkers or therapeutic targets for radon-related lung cancer.

Previous studies on cohorts of radiation workers have provided valuable insights into the effects of low-dose-rate radiation; however, some concerns regarding the potential confounding effects of smoking have been expressed. Although some studies have collected smoking data and adjusted for this variable, their limited numbers and the presence of other confounders obscure the extent of the impact of smoking on their results. To address this, we conducted a simulation study to quantitatively evaluate the bias from confounding and modeling conditions, similar to actual epidemiological studies. Our analysis, based on data from Japanese radiation workers, indicated that not adjusting for smoking can lead to an overestimation of radiation effects by approximately 110%. This overestimation was relatively insensitive to sample size and dose distribution parameters, but varied with radiation and smoking risk, baseline smoking probability, and heterogeneity in baseline risk. Considering the simplified settings of this simulation study and the uncertainty of the estimates of Japanese radiation workers, our simulation results were consistent with those of the real-world epidemiological study. We also compared the results using Cox and Poisson regression models, ensuring that their modeling approaches were as similar as possible, and found minimal differences between them.

High dose rate (HDR) intracavitary brachytherapy (ICBT) with a remote afterloading system plays a vital role in the treatment of cervical cancer. We aimed to develop a new verification system for ICBT for cervical cancer and evaluate the feasibility for clinical plans (PlanClin) generated for different remote afterloaders, applicators and treatment techniques. In total, 517 PlansClin of patients were treated with Elekta 192Ir microSelectron HDR v2r. Reference plans (PlanRef) were generated for the ICBT applicators. An equation to predict total dwell time (Tdwell) of PlanClin was generated by evaluating the relationship between the volume receiving 100% of the prescribed dose (V100%) and the Tdwell. We also developed software to detect human errors in PlanClin by comparing parameters, including applicator and reference point geometries, dwell position and weight patterns and reference point dose, with those of PlanRef. Feasibility was evaluated for 83 PlanClin cases treated with the Elekta Flexitron remote afterloader and six ICBT plans with extra catheters (hybrid BT). The linear fitting function showed good agreement with the correlation between V100% and Tdwell. The developed equation accurately estimated the Tdwell of the PlanClin treated with the Flexitron with an accuracy of 0.26 ± 0.49%. Our system successfully detected intentional human errors including incorrect channel mapping, applicator tip offset, incorrect plan templates, an applicator digitization model and incorrect reference points. A verification system based on PlanRef and a statistical approach is feasible for the new remote afterloaders, applicators and hybrid BT techniques. This system contributes to the implementation of safe treatments.

Ventricular tachycardia (VT) is a severe arrhythmia commonly treated with implantable cardioverter defibrillators, antiarrhythmic drugs and catheter ablation (CA). Although CA is effective in reducing recurrent VT, its impact on survival remains uncertain, especially in patients with extensive scarring. Stereotactic arrhythmia radioablation (STAR) has emerged as a novel treatment for VT in patients unresponsive to CA, leveraging techniques from stereotactic body radiation therapy used in cancer treatments. Recent clinical trials and case series have demonstrated the short-term efficacy and safety of STAR, although long-term outcomes remain unclear. Imaging techniques, such as electroanatomical mapping, contrast-enhanced magnetic resonance imaging and nuclear imaging, play a crucial role in treatment planning by identifying VT substrates and guiding target delineation. However, challenges persist owing to the complex anatomy and variability in target volume definitions. Advances in imaging and artificial intelligence are expected to improve the precision and efficacy of STAR. The exact mechanisms underlying the antiarrhythmic effects of STAR, including potential fibrosis and improvement in cardiac conduction, are still being explored. Despite its potential, STAR should be cautiously applied in prospective clinical trials, with a focus on optimizing dose delivery and understanding long-term outcomes. Collaborative efforts are necessary to standardize treatment strategies and enhance the quality of life for patients with refractory VT.

We assessed the effect of beam size on plan robustness for intensity-modulated proton therapy (IMPT) of head and neck cancer (HNC) and compared the plan quality including robustness with that of intensity-modulated radiation therapy (IMRT). IMPT plans were generated for six HNC patients using six beam sizes (air-sigma 3-17 mm at isocenter for a 70-230 MeV) and two optimization methods for planning target volume-based non-robust optimization (NRO) and clinical target volume (CTV)-based robust optimization (RO). Worst-case dosimetric parameters and plan robustness for CTV and organs-at-risk (OARs) were assessed under different scenarios, assuming a ± 1-5 mm setup error and a ± 3% range error. Statistical comparisons of NRO-IMPT, RO-IMPT and IMRT plans were performed. In regard to CTV-D99%, RO-IMPT with smaller beam size was more robust than RO-IMPT with larger beam sizes, whereas NRO-IMPT showed the opposite (P < 0.05). There was no significant difference in the robustness of the CTV-D99% and CTV-D95% between RO-IMPT and IMRT. The worst-case CTV coverage of IMRT (±5 mm/3%) for all patients was 96.0% ± 1.4% (D99%) and 97.9% ± 0.3% (D95%). For four out of six patients, the worst-case CTV-D95% for RO-IMPT (±1-5 mm/3%) were higher than those for IMRT. Compared with IMRT, RO-IMPT with smaller beam sizes achieved lower worst-case doses to OARs. In HNC treatment, utilizing smaller beam sizes in RO-IMPT improves plan robustness compared to larger beam sizes, achieving comparable target robustness and lower worst-case OARs doses compared to IMRT.

This retrospective study aimed to compare the clinical outcomes of intensity-modulated radiation therapy (IMRT) and proton beam therapy (PBT). A total of 606 patients diagnosed with prostate cancer between January 2008 and December 2018 were included. Of these patients, 510 received PBT up to a dose of 70-78 Gy (relative biological effectiveness) and 96 patients received IMRT up to a dose of 70-78 Gy. The median follow-up period was 82 months (range: 32-140 months). Patients in the PBT group had significantly higher 7-year rates of biochemical relapse-free survival (bRFS) and disease-free survival (DFS) rates: 95.1% for PBT vs 89.9% for IMRT (P = 0.0271) and 93.1% for PBT vs 85.0% for IMRT (P = 0.0019). After matching analysis, 94 patients were assigned to both groups, and the PBT group showed significantly higher 7-year bRFS and DFS rates: 98.9% for PBT vs 89.7% for IMRT (P = 0.023) and 93.4% for PBT vs 84.6% for IMRT (P = 0.022), respectively. In the subgroup analysis of intermediate-risk patients, the PBT group showed a significantly higher 7-year bRFS rate (98.3% for PBT vs 90.5% for IMRT; P = 0.007). The V60 of the bladder in the PBT group (18.1% ± 10.1%) was higher than that in the IMRT group (14.4% ± 7.6%) (P = 0.024). This study found that the treatment outcomes of PBT potentially surpassed those of IMRT specifically concerning bRFS and DFS in real-world settings. However, it should be noted that attention is warranted for late bladder complication of PBT.

Dynamic WaveArc (DWA) is a technique used for continuous, non-coplanar volumetric-modulated arc therapy on the Vero4DRT platform. This study aimed to evaluate the application of single-isocenter DWA (SI-DWA) for treating multiple brain metastases by comparing dose distribution and irradiation time with multi-isocenter DWA (MI-DWA) through retrospective treatment planning. Treatment plans were developed for SI-DWA and MI-DWA in 14 cases with 3-5 brain metastases. Parameters assessed included target dose indices, such as conformity index (CI) of the planning target volume (PTV), volumes of normal brain excluding gross tumor volumes (GTVs) receiving a single dose equivalent of 14 Gy (V14), V30%, V20%, V10%, volumes of normal brain, including GTVs receiving a single dose equivalent of 12 Gy (V12), D2% for other organs at risk, and beam-on time. SI-DWA showed inferior CI, V14, and V12 values for lesions with PTV volumes <1 cc, whereas it performed equivalently to MI-DWA for lesions with PTV volumes ≥1 cc. SI-DWA resulted in higher volumes of normal brain receiving low doses compared to MI-DWA. SI-DWA exhibited significantly shorter beam-on times than MI-DWA. In conclusion, SI-DWA is an effective method for treating multiple brain metastases with PTV volumes ≥1 cc, offering an index of radiation-induced brain necrosis comparable with MI-DWA while allowing for shorter irradiation times.