Helical Tomotherapy Research Articles

Dosimetric Comparison and Selection Criteria of Intensity-Modulated Proton Therapy and Intensity-Modulated Radiation Therapy for Adaptive Re-Plan in T3-4 Nasopharynx Cancer Patients.

Proton therapy requires caution when treating patients with targets near neural structures. Intuitive and quantitative guidelines are needed to support decision-making concerning the treatment modality. This study compared dosimetric profiles of intensity-modulated proton therapy (IMPT) and intensity-modulated radiation therapy (IMRT) using helical tomotherapy (HT) for adaptive re-planning in cT3-4 nasopharyngeal cancer (NPCa) patients, aiming to establish criteria for selecting appropriate treatment modalities. HT and IMPT plans were generated for 28 cT3-4 NPCa patients undergoing definitive radiotherapy. Dosimetric comparisons were performed for target coverage and high-priority organs at risk (OARs). The correlation between dosimetric parameters and RT modality selection was analyzed with the target OAR distances. Target coverages were similar, while IMPT achieved better dose spillage. HT was more favorable for brainstem D1, optic chiasm Dmax, optic nerves Dmax, and p-cord D1. IMPT showed advantages for oral cavity Dmean. Actually, 14 IMPT and 14 HT plans were selected as adaptive plans, with IMPT allocated to most cT3 patients (92.9% vs. 42.9%, p = 0.013). The shortest distances from the target to neural structures were negatively correlated with OAR doses. Receiver operating characteristic curve analyses were carried out to discover the optimal cut-off values of the shortest distances between the target and the OARs (temporal lobes and brainstem), which were 0.75 cm (AUC = 0.908, specificity = 1.00) and 0.85 cm (AUC = 0.857, specificity = 0.929), respectively. NPCa patients with cT4 tumor or with the shortest distance between the target and critical neural structures < 0.8 cm were suboptimal candidates for IMPT adaptive re-planning. These criteria may improve resource utilization and clinical outcomes.

Locally Advanced Childhood Nasopharyngeal Cancer: A Case Series

Nasopharyngeal carcinoma is a rare malignant tumor in childhood. To date, no consensus has been achieved concerning the recommendations for the management of childhood Nasopharyngeal carcinoma. Chemotherapy and radiotherapy are the main modalities in the management of nasopharyngeal carcinoma (NPC). Five cases (with an age range between 10 and 16 years), including one patient with stage III NPC and four patients with stage IV NPC, are reported in this study. All patients received four courses of induction chemotherapy followed by concurrent chemoradiation with cumulative irradiation, with a dose of 70 Gy in 33-37 fractions. Patients were treated with intensity modulated radiation therapy with simultaneous integrated boost technique using helical Tomotherapy. After two-year’s follow-up, four patients were achieved complete response, one patient showed residual disease in lymph nodes in the neck and bone metastases one year after the completion of treatment. Treatment side effects were well tolerated, there was no acute toxicity grade 3 or 4, and late toxicity consisted of chronic sinusitis, grade 1 xerostomia, and grade 1 skin fibrosis.

Improved quality of life in head and neck cancer patients treated with modern arc radiotherapy techniques - A prospective longitudinal analysis.

The present longitudinal study aimed to evaluate the potential impact of modern radiotherapy (RT) techniques on quality of life (QOL) in patients with head and neck (HNC) cancer. In this single-center prospective study, participants were asked to complete QOL questionnaires that included the EORTC QLQ-C30, QLQ-H&N 35 and utility score by time trade-off (TTO) at three time points (2 weeks, 3 months and 6 months) after completion of RT. All patients were treated by modern RT techniques [volumetric modulated arc therapy (VMAT) or helical tomotherapy (HT)]. Patients who developed recurrence or died before the 6-month follow-up were excluded. Linear mixed models with random intercepts for participants and restricted maximum likelihood estimates were used to assess the effect of our study variables (age, sex, primary site, cancer stage, treatment, radiation dose and radiation method). Overall changes in QOL, utility scores and symptom burdens at different time points were tested using paired t tests. A total of 45 patients were recruited from 2022 to 2023. Those who completed the surveys at 2 weeks with at least 1 follow-up (30 patients, 67%) were enrolled in the final analysis. The majority of these 30 patients were men (76.7%), had oral cancer (40%), had stage III or IV disease (60%), received surgical intervention (63%) and were treated with chemoradiation (80%). A curative total dose of 66 to 70 Gy was delivered to 23 (76.7%) patients, half of whom received HT. Patients who received chemotherapy had significantly lower global QoL scales (mean difference, 27.94; 95% CI, 9.33-46.55; p=0.005). Global QOL, physical function, symptoms of sticky saliva, cough, feelings of illness and weight loss improved significantly between 2 weeks and 3 months. There was no significant difference between 3 and 6 months. Interestingly, improvements in social function, social contact, pain and nutrition reached significance at 6 months. Subgroup analysis revealed greater pain relief over time for patients who underwent HT (p=0.030). Moreover, patients who participated in swallowing rehabilitation programs had a greater decrease in nausea and vomiting (p=0.036). HNC patients treated with modern RT techniques experience improved QOL and physical function over time. The most significant improvement occurs between 2 weeks and 3 months, after which the improvement plateaus. However, social function, social contact, pain and nutrition may require longer recovery intervals after treatment. HT with daily image guidance could provide a therapeutic opportunity for improving pain relief in patients with HNC.

Evaluation and Comparison of the Dose Received by the Mandible, Maxilla, and Teeth in Two Methods of Three-dimensional Conformal Radiation Therapy and Helical Tomotherapy.

Using three-dimensional conformal radiation treatment (3D-CRT) and helical tomotherapy (HT), this study examines and contrasts the dosage received by the mandible, maxilla, and teeth. Sixteen patients with head-and-neck cancer (H and NC) were the subject of treatment planning at the Seyyed Al-Shohada Hospital in Isfahan, Iran. This study examined target coverage quality, exposure of healthy tissue, and radiation delivery effectiveness. In terms of a number of measures, including D2%, D50%, Dmean, V95%, conformity index (CI), and homogeneity index (HI) for the planning target volume (PTV) and D2%, D98%, Dmean, V95%, CI, and HI for the nodal PTV, HT showed considerable gains over 3D-CRT. The brainstem, D1cc, and D10cc received considerably lower maximum dosages in HT. Measurements of the right and left cochleas (Dmean, V55, and Dmax) revealed decreases in HT, with Dmean revealing the most significant variations. The Dmean and Dmax values for HT significantly decreased in constrictors as well. In terms of several HT-related indicators, the larynx, optic chiasm, optic nerves, oral cavity, mandible, thyroid, and parotid glands all showed considerable decreases. The findings of the comparison of the two treatment approaches revealed that the HT method was more than 50% more effective than the 3D-CRT method in sustaining organs at risk (OARs) and the target volume dose. In general, dosimetric coverage, homogeneity, conformity indices, and the absence of cold and hot patches showed that HT produced targets with greater accuracy than 3D-CRT. In addition, HT outperformed 3D-CRT in protecting important structures (OARs). HT as a result has the potential to be a more effective method of treatment for those with H and NC and involvement of regional lymph nodes.

153 Outcomes Assessment of Helical Tomotherapy in Definitive Radiation: A Retrospective Analysis of Disease Response and Patient Survival

153 Outcomes Assessment of Helical Tomotherapy in Definitive Radiation: A Retrospective Analysis of Disease Response and Patient Survival

2797: Initial Clinical and Dosimetric outcomes with TBI planned on Helical Tomotherapy

2797: Initial Clinical and Dosimetric outcomes with TBI planned on Helical Tomotherapy

348: Dosimetric comparison of helical tomotherapy plans in breast cancer patients with silicone implants

348: Dosimetric comparison of helical tomotherapy plans in breast cancer patients with silicone implants

Technical note: A software tool to extract complexity metrics from radiotherapy treatment plans.

Complexity metrics are mathematical quantities designed to quantify aspects of radiotherapy treatment plans that may affect both their deliverability and dosimetric accuracy. Despite numerous studies investigating their utility, there remains a notable absence of shared tools for their extraction. This study introduces UCoMX (Universal Complexity Metrics Extractor), a software package designed for the extraction of complexity metrics from the DICOM-RT plan files of radiotherapy treatments. UCoMX is developed around two extraction engines: VCoMX (VMAT Complexity Metrics Extractor) for VMAT/IMRT plans, and TCoMX (Tomotherapy Complexity Metrics Extractor) tailored for Helical Tomotherapy plans. The software, built using Matlab, is freely available in both Matlab-based and stand-alone versions. More than 90 complexity metrics, drawn from relevant literature, are implemented in the package: 43 for VMAT/IMRT and 51 for Helical Tomotherapy. The package is designed to read DICOM-RT plan files generated by most commercially available Treatment Planning Systems (TPSs), across various treatment units. A reference dataset containing VMAT, IMRT, and Helical Tomotherapy plans is provided to serve as a reference for comparing UCoMX with other in-house systems available at other centers. UCoMX offers a straightforward solution for extracting complexity metrics from radiotherapy plans. Its versatility is enhanced through different versions, including Matlab-based and stand-alone, and its compatibility with a wide range of commercially available TPSs and treatment units. UCoMX presents a free, user-friendly tool empowering researchers to compute the complexity of treatment plans efficiently.

A Multicentric study on a dosimetric comparison of extended SSD technique, VMAT-Based and helical tomotherapy (HT) for total body irradiation (TBI)

PurposeIn study, it was aimed to evaluate the dose volume histograms (DVH) of extended SSD technique, VMAT-based, and helical tomotherapy plans dosimetrically in a multi-institutional context to achieve higher plan quality and to harmonize total body irradiation plans. MethodsFour different clinical centers participated in the study. The CT images of ten patients were used in this study. During the first phase, ten patients enrolled for TBI were planned by multiple centers according to a common protocol. During the second phase, all centers shared their plans’ DVHs. Treatment plans were evaluated according to the critical organ dose limits. Statistical analysis was performed in the SPSS (version 22.0) program (p < 0.05). ResultsIn study, the results indicated that there was a statistically significant and considerable difference in the dose coverage of PTV, beam delivery time and MU, lens doses, and kidney doses between the four techniques (p < 0.001). The mean lung doses of the four centers were below 10 Gy. No significant difference in maximum liver doses between plans was obtained. ConclusionIn conclusion, although four treatment techniques were suitable for TBI treatment, more homogeneous dose distribution, and lower critical organ doses were obtained with the tomotherapy technique. However, treatment time, MU, and dose rate for lung were disadvantages of the tomotherapy technique. When it comes to deciding on the TBI treatment method, it need to be reviewed some important points. It is needed to sufficient data on long-term results to be able to standardize TBI techniques between centers.

Current dilemma and future directions over prophylactic cranial irradiation in SCLC: a systematic review in MRI and immunotherapy era.

Small cell lung cancer (SCLC) is the most malignant pathological type of lung cancer with the highest mortality, and the incidence of brain metastasis (BM) is in high frequency. So far, prophylactic cranial irradiation (PCI) has been suggested as an effective treatment for preventing brain metastasis of SCLC. PCI has long been applied to limited-stage SCLC (LS-SCLC) patients who have achieved complete remission after radiotherapy and chemotherapy as a standard treatment. However, the neurocognitive decline is a major concern surrounding PCI. New therapeutic approaches targeting PCI-induced neurotoxicity, including hippocampal protection or memantine, have been increasingly incorporated into the therapeutic interventions of PCI. Helical tomotherapy, RapidArc, and Volumetric-modulated arc therapy (VMAT) with a head-tilting baseplate are recommended for hippocampal protection. Besides, in the MRI and immunotherapy era, the significance of PCI in SCLC patients is controversial. SCLC patients with PCI should be recruited in clinical trials since this is the only way to improve the existing standard of care. This review summarizes the current therapeutic strategy and dilemma over PCI for SCLC, providing a theoretical basis for clinical decision-making and suggestions for PCI practice in clinical.

Dosiomics-based detection of dose distribution variations in helical tomotherapy for prostate cancer patients: influence of treatment plan parameters.

The stability of dosiomics features (DFs) and dose-volume histogram (DVH) parameters for detecting disparities in helical tomotherapy planned dose distributions was assessed. Treatment plans of 18 prostate patients were recalculated using the followings: field width (WF) (2.5 vs. 5), pitch factor (PF) (0.433 vs. 0.444), and modulation factor (MF) (2.5 vs. 3). From each of the eight plans per patient, ninety-three original and 744 wavelet-based DFs were extracted, using 3D-Slicer software, across six regions including: target volume (PTV), pelvic lymph nodes (PTV-LN), PTV + PTV-LN (PTV-All), one cm rind around PTV-All (PTV-Ring), rectum, and bladder. For the resulting DFs and DVH parameters, the coefficient of variation (CV) was calculated, and using hierarchical clustering, the features were classified into low/high variability. The significance of parameters on instability was analyzed by a three-way analysis of variance. All DF's were stable in PTV, PTV-LN, and PTV-Ring (average CV ( ≤0.36). Only one feature in the bladder ( =0.9), rectum ( =0.4), and PTV-All ( =0.37) were considered unstable due to change in MF in the bladder and WF in the PTV-All. The value of for the wavelet features was much higher than that for the original features. Out of 225 unstable wavelet features, 84 features had ≥1. The CVs for all the DVHs remained very small ( <0.06). This study highlights that the sensitivity of DFs to changes in tomotherapy planning parameters is influenced by the region and the DFs, particularly wavelet features, surpassing the effectiveness of DVHs.

DeCoGAN: MVCT image denoising via coupled generative adversarial network

Objective. In helical tomotherapy, image-guided radiotherapy employs megavoltage computed tomography (MVCT) for precise targeting. However, the high voltage of megavoltage radiation introduces substantial noise, significantly compromising MVCT image clarity. This study aims to enhance MVCT image quality using a deep learning-based denoising method. Approach. We propose an unpaired MVCT denoising network using a coupled generative adversarial network framework (DeCoGAN). Our approach assumes that a universal latent code within a shared latent space can reconstruct any given pair of images. By employing an encoder, we enforce this shared-latent space constraint, facilitating the conversion of low-quality (noisy) MVCT images into high-quality (denoised) counterparts. The network learns the joint distribution of images from both domains by leveraging samples from their respective marginal distributions, enhanced by adversarial training for effective denoising. Main Results. Compared to an analytical algorithm (BM3D) and three deep learning-based methods (RED-CNN, WGAN-VGG and CycleGAN), the proposed method excels in preserving image details and enhancing human visual perception by removing most noise and retaining structural features. Quantitative analysis demonstrates that our method achieves the highest peak signal-to-noise ratio and Structural Similarity Index Measurement values, indicating superior denoising performance. Significance. The proposed DeCoGAN method shows remarkable MVCT denoising performance, making it a promising tool in the field of radiation therapy.

Helical Tomotherapy Versus 3-Dimensional Conformal Radiation Therapy in High-Risk Prostate Cancer: A Phase 3 Randomized Controlled Trial

We present long-term outcomes from a phase 3 randomized controlled trial that compared helical tomotherapy with 3-dimensional conformal radiation therapy (3D-CRT) in the treatment of high-risk prostate cancer. Newly diagnosed patients with high-risk prostate cancer were randomly allocated to receive radical radiation therapy (RT) using 3D-CRT or helical tomotherapy. In both arms, patients received an initial dose of 46 Gy in 23 fractions to the prostate and pelvic lymph nodes, followed by an additional boost to the prostate of 32 Gy in 16 fractions. RT was combined with 3 years of adjuvant androgen deprivation. The primary endpoint was late (>90 days since RT initiation) rectal toxicity. Overall,123 patients were randomly assigned to either the 3D-CRT (n = 60) or tomotherapy (n = 63) arms. The median follow-up was 161 months. Overall, the proportion of patients with grade ≥ 2 late rectal toxicity was 8.3% (95% CI, 3.1-19.1; n = 5) in the 3D-CRT arm and 11.1% (95% CI, 5.0-22.2; n = 7) in the tomotherapy arm with no significant between-arm difference (P = .83). There was no significant difference (P = .17) in the proportion of patients with late grade ≥ 2 genitourinary toxicity:10.0% (95% CI, 4.1-21.2) in the 3D-CRT arm and 20.6% (95% CI, 11.9-33.0) in the tomotherapy arm. There was no significant difference in the hazard of biochemical progression or death between the 2 groups (hazard ratio for the tomotherapy arm: 0.72; 95% CI, 0.46-1.15; P = .17). In this phase 3 trial, the overall incidence of grade ≥ 2 rectal toxicity was low and was not significantly different between the 2 arms. There was no significant evidence of improved biochemical progression-free survival in patients treated with tomotherapy. These findings should be interpreted considering the possibility of type II errors due to limited sample size and low event rates.

Using dose volume histogram (DVH) predictions to improve the plan quality of helical tomotherapy (HT)

This study aimed to investigate whether the RapidPlan (RP) model configured by volumetric modulated arc therapy (VMAT) plans of nasopharyngeal carcinoma (NPC) could be used to assist in the optimization of HT plans and improve their quality.An RP model was trained using 100 clinically accepted VMAT plans of NPC patients. The predicted dose constraints of the VMAT trained RP model were used to reoptimize 25 consecutive clinically accepted HT plans (HT_clinical) and perform new VMAT plans based on the same computed topography (CT). The dosimetric quality of the reoptimized HT plans (HT_reoptimized), HT_clinical, and VMAT group were compared. The minimum dose encompassing 2% target (D2%), the minimum dose encompassing 98% target (D98%), homogeneity index (HI) and conformity index (CI) were similar for most targets between the HT_clinical and HT_reoptimized plans, although certain targets in the HT_reoptimized plans had higher D2% and HI and lower D98%. The HT_reoptimized plans outperformed the HT_clinical plans in the Dmax and D1cc of the spinal cord, V40Gy of the left temporal lobe, Dmean and V30Gy of the oral cavity, Dmean of the larynx and thyroid, and the differences were statistically significant. HT plans had higher CI and HI than VMAT plans. HT plans outperformed VMAT plans in the Dmax of the spinal cord and lenses, V30Gy of the oral cavity and parotids, and V40Gy of the temporal lobes, but underperformed in the Dmax and D1cc of the brainstem, D1cc of the spinal cord and Dmean of the oral cavity.The VMAT-based RP model can be used to assist in the planning of HT plans and improve the dosimetry quality of HT plans.

Helical tomotherapy was superior to intensity-modulated radiation therapy in hippocampal avoidance prophylactic cranial irradiation in patients with limited-stage small-cell lung cancer.

e20099 Background: Hippocampal avoidance (HA) techniques have been developed to reduce the risk of neurocognitive dysfunction associated with prophylactic cranial irradiation (PCI) in patients with limited-stage small-cell lung cancer (LS-SCLC). However, applying different radiotherapy techniques to HA has not yet been further analyzed. This study discussed the dosimetric differences between intensity-modulated radiation therapy (IMRT) and helical tomotherapy (TOMO) in HA-PCI and analyzed the benefit of the dosimetric advantage in the risk of brain metastasis (BM) from a clinical perspective. Methods: We retrospectively evaluated patients who underwent PCI from June 2020 to December 2021 at Shandong Cancer Hospital. They were divided according to hippocampal avoidance and radiotherapy techniques: IMRT without HA (non-HA-IMRT), HA-IMRT, and HA-TOMO. The cumulative incidence of BM, target coverage (TC), homogeneity index (HI), conformity index (CI), and hippocampal doses of these radiotherapy programs were evaluated. Results: One hundred seventy-two patients were included in the analysis: 56, 78, and 38 patients in the non-HA-IMRT, HA-TOMO, and HA-IMRT groups, respectively. The 2-year cumulative incidence of BM was 31.4% in patients with HA (78 patients in the HA-TOMO group and 38 patients in the HA-IMRT group) and 23.2% in patients without HA (hazard ratio [HR]: 0.75, 95% confidence interval [95% CI]: 0.43-1.31; P= 0.340). However, the 2-year cumulative incidence of BM was lower in the HA-TOMO group than in the HA-IMRT group (25.0% vs. 44.7%, HR: 0.51, 95% CI: 0.26-0.99; P= 0.029). Both techniques achieved hippocampal protection, but HA-TOMO accomplished significantly better TC (96.24%±0.65% vs. 93.75%±2.45%, P&lt; 0.001), HI (0.09±0.02 vs. 0.27±0.12, P&lt; 0.001), and CI (0.88±0.02 vs. 0.85±0.04, P&lt; 0.001). Conclusions: HA-PCI did not increase BM risk. Additionally, HA-TOMO could achieve better TC, HI, and CI with respect to the planned tumor in the brain while achieving more rapid dosing in the hippocampal region. The cumulative incidence of BM was lower with HA-TOMO than with HA-IMRT.

Determinants of radiation dose to immune cells during breast radiotherapy.

The immune system has been identified as an organ at risk in esophageal and lung cancers. However, the dosimetric impact of radiotherapy on immune system exposure in patients treated for breast cancer has never been studied. Amonocentric retrospective dosimetric study included 163 patients treated at the Institut Curie (Paris, France) between 2010 and 2016 with locoregional helical tomotherapy after conservative surgery or total mastectomy. The effective dose to the immune system (EDIC) was calculated based on diverse dosimetric parameters. The clinical and volumetric determinants of EDIC in adjuvant radiotherapy of breast cancer were analyzed. The median EDIC for the population was 4.23 Gy, ranging from 1.82 to 6.19Gy. Right-sided radiotherapy and regional lymph node irradiation were associated with significantly higher EDIC in univariate (4.38 Gy vs. 3.94 Gy, p < 0.01, and 4.27 Gy vs. 3.44 Gy, p < 0.01, respectively) and multivariate analyses (p < 0.01 and p < 0.01). Liver overexposure was the main contributor to EDIC increase in right-sided breast cancer patients (+0.38 Gy [95%CI: +0.30; +0.46]), while the integral total dose increase was the main contributor to EDIC increase in cases of regional node irradiation (+0.63 Gy [95%CI: +0.42; +0.85]). The EDIC score during adjuvant radiotherapy after breast cancer was statistically significantly higher in the case of right-sided radiotherapy and regional lymph node irradiation. Liver irradiation is the main contributor to immune system exposure in adjuvant irradiation of right-sided breast cancer. Populations in which an association between EDIC and survival would exist have yet to be identified but could potentially include patients treated for triple-negative breast cancer with apoor response to neoadjuvant chemoimmunotherapy.

Influence of the Planning Parameters of a New Algorithm on the Dosimetric Quality, Beam-on Time and Delivery Accuracy of Tomotherapy Plans

Background: This work aimed to determine the optimum VOLOTM Ultra algorithm parameters for tomotherapy treatments. Methods: 1056 treatment plans were generated with VOLOTM Ultra for 36 patients and six anatomical locations. The impact of varying four parameters was studied: the accelerated treatment (AT), leaf open/close time (LOT) cutoff, normal tissue objective (NTO) weight, and number of iterations. The beam-on time and dosimetric metrics were quantified for the target volumes and organs at risk (OARs). Delivery quality assurance measurements were obtained for 36 plans to assess the delivery accuracy. Results: The mean beam-on time for the helical tomotherapy and TomoDirect (TD) plans decreased by 26.6 ± 2.8% and 17.4 ± 4.3%, respectively, when the accelerated treatment parameter was increased from 0 to 10, at the expense of the planning target volume (PTV) coverage (2% lower D98%) and OAR dose (up to 15% increase). For TD plans, it seems preferable to systematically use an AT value of 10. Increasing the number of iterations beyond six seems unnecessary. In this study, an NTO weight of approximately 10 appears to be ideal and eliminates the need to use rings in the treatment plan. Finally, no correlation was found between the leaf open/close time cutoff and the delivery accuracy, while a leaf open/close cutoff of 60 ms seemed to degrade dosimetry quality. Conclusion: Optimal values for the AT, LOT cutoff, NTO weight, and number of optimization rounds were identified and should help improve the management of patients whose tomotherapy treatments are planned with VOLOTM Ultra.

Factors Influencing Long-Term Local Recurrence, Distant Metastasis, and Survival in Patients with Soft Tissue Sarcoma of the Extremities Treated with Radiotherapy

Introduction: The prognostic factors for extremity soft-tissue sarcomas (ESTSs) treated with multimodal surgery and radiotherapy (RT) remain a subject of debate across diverse and heterogeneous studies. Methods: We retrospectively analyzed nonmetastatic ESTS patients treated with RT between 2007 and 2020 in Strasbourg, France. We assessed local control (LC), distant control (DC), overall survival (OS), and complications. Results: A total of 169 patients diagnosed with localized ESTS were included. The median age was 64 years (range 21–94 years). ESTS primarily occurred proximally (74.6%) and in the lower limbs (71%). Most tumors were grade 2–3 (71.1%), deep-seated (86.4%), and had R0 margins (63.9%). Most patients were treated with helical tomotherapy (79.3%). The median biologically effective dose (BED) prescribed was 75 BEDGy4 (range 45.0–109.9). The median follow-up was 5.5 years. The 5- and 10-year LC, DC, and OS rates were 91.7%, 76.8%, and 83.8% and 84.2%, 74.1%, and 77.6%, respectively. According to the univariate analysis, LC was worse for patients who received less than 75 BEDGy4 (p = 0.015). Deep tumors were associated with worse OS (p &lt; 0.05), and grade 2–3 and undifferentiated pleomorphic sarcoma (UPS) were linked to both shorter DC and shorter OS (p &lt; 0.05). IMRT was associated with longer LC than 3DRT (p = 0.018). Multivariate analysis revealed that patients with liposarcoma had better OS (p &lt; 0.05) and that patients with distant relapse had shorter OS (p &lt; 0.0001). Conclusion: RT associated with surgical resection was well tolerated and was associated with excellent long-term rates of LC, DC, and OS. Compared with 3DRT, IMRT improved local control. Liposarcoma was a favorable prognostic factor for OS. Intermediate- and high-grade tumors and deep tumors were associated with lower DC and OS.

Locally advanced nasopharyngeal carcinoma in adolescents treated with tomotherapy: Experience at King Faisal Specialist Hospital and Research Centre.

Nasopharyngeal carcinoma (NPC) is a rare disease worldwide; To the best of our knowledge, there is no established standard of care specifically tailored for the adolescent population. The majority of existing research relies on retrospective data analysis. Evaluate clinical features, treatment results, prognostic factors and late toxicities of locally advanced NPC patients treated with tomotherapy. Retrospective. Tertiary care hospital. Between January 2007 and January 2020, we treated patients with NPC, aged between 14 and 21 years, with concomitant chemoradiotherapy using tomotherapy at our institution. We prospectively collected details of clinical characteristics, treatment modalities, outcomes and prognostic factors of these patients and then analysed them retrospectively. 3-5 years overall survival (OS), 3-5 years locoregional control rate, 3-5 years disease-free survival (DFS), prognostic factors. 51 patients. There were 26 male and 25 female patients included in our study. The mean age was 16.5 years, 5 (9.8%) patients with stage III, and 46 (90.2%) with stage IVa according to the American Joint Committee on Cancer, 8th edition staging system. Most patients (98%) received two or more cycles of induction chemotherapy. All patients received concomitant chemoradiotherapy. The median total dose of radiotherapy delivered was 6600 cGy (range 4800-7000). With a median follow-up of 73 months (range 9-168 months), a 5-year locoregional control rate, 5-year OS and 5-year DFS rates were 100%, 86.8% and 71.7%, respectively. Five years later, disease control was 71.7%. Ten (19.6%) patients had disease recurrence in the form of distant metastases during the follow up. Helical tomotherapy has an excellent late toxicity profile without compromising clinical outcome for patients with NPC. Radiotherapy remains the mainstay of treatment of nasopharyngeal carcinoma to achieve remarkable local control rates. Single institution experience, small number of patients, and retrospective design.

3407: efficacy and toxicity of moderately hypofractionated radiotherapy via helical tomotherapy versus conventional radiotherapy combined with concurrent chemotherapy for patients with unresectable stage III non-small cell Lung Cancer: a multicenter, randomized phase III trial Chinese clinical trial registration: ChiCTR1800017367

3407: efficacy and toxicity of moderately hypofractionated radiotherapy via helical tomotherapy versus conventional radiotherapy combined with concurrent chemotherapy for patients with unresectable stage III non-small cell Lung Cancer: a multicenter, randomized phase III trial Chinese clinical trial registration: ChiCTR1800017367