Respiratory motion tracking of spine stereotactic radiotherapy in prone position.

PURPOSE: The CyberKnife system is a specialized device for non-coplanar irradiation; however, it possesses the geometric restriction that the beam cannot be irradiated from under the treatment couch. Prone positioning is expected to reduce the dose to normal lung tissue in spinal stereotactic body radiotherapy (SBRT) owing to the efficiency of beam arrangement; however, respiratory motion occurs. Therefore, the Xsight spine prone tracking (XSPT) system is used to reduce the effects of respiratory motion. The purpose of this study was to evaluate the motion-tracking error of the spine in the prone position. MATERIALS AND METHODS: Data from all 25 patients who underwent spinal SBRT at our institution between April 2020 and February 2022 using CyberKnife (VSI, version 11.1.0) with the XSPT tracking system were retrospectively analyzed using log files. The tumor motion, correlation, and prediction errors for each patient were examined. Furthermore, to assess the potential relationships between the parameters, the relationships between the tumor-motion amplitudes and correlation or prediction errors were investigated using linear regression. RESULTS: The tumor-motion amplitudes in each direction were as follows: superior-inferior (SI), 0.51 ± 0.39 mm; left-right (LR), 0.37 ± 0.29 mm; and anterior-posterior (AP), 3.43 ± 1.63 mm. The overall mean correlation and prediction errors were 0.66 ± 0.48 mm and 0.06 ± 0.07 mm, respectively. The prediction errors were strongly correlated with the tumor-motion amplitudes, whereas the correlation errors were not. CONCLUSIONS: This study demonstrated that the correlation error of spinal SBRT in the prone position is sufficiently small to be independent of the tumor-motion amplitude. Furthermore, the prediction error is small, contributing only slightly to the tracking error. These findings will improve the understanding of how to compensate for respiratory-motion uncertainty in the prone position.

Efficacy and safety of chemoradiation therapy using one-shot cisplatin via hepatic arterial infusion for advanced hepatocellular carcinoma with major macrovascular invasion: a single-arm retrospective cohort study.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) and macrovascular invasion (MVI) who receive systemic chemotherapy have a poor prognosis. This study aimed to determine if one-shot cisplatin (CDDP) chemotherapy via hepatic arterial infusion (HAI) combined with radiation therapy (RT) prior to systemic chemotherapy could improve the outcomes of these patients. METHODS: This study consisted of 32 HCC patients with the following eligibility criteria: (i) portal vein invasion 3/4 and/or hepatic vein invasion 2/3; (ii) received one-shot CDDP via HAI; (iii) received RT for MVI, (iv) a Child-Pugh score ≤ 7; and (v) an Eastern Clinical Oncology Group Performance Status score of 0 or 1. To determine the therapeutic effect, we collected information on patient characteristics and took contrast-enhanced computed tomography at the start of the therapy and every 2 to 4 months after the start of therapy. We evaluated the overall response of the tumor and tumor thrombosis according to modified Response Evaluation Criteria in Solid Tumors. We assessed patient data using the Mann-Whitney U and Fisher exact tests and evaluated overall survival and progression-free survival using the log-rank test. RESULTS: The overall response rate at the first evaluation performed a median of 1.4 weeks after HAI was 16% for the main intrahepatic tumor and 59% for the MVI. The best responses were the same as those of the first-time responses. The duration of median survival was 8.6 months, and progression-free survival of the main intrahepatic tumor was 3.2 months. Predictive factors for overall survival were the relative tumor volume in the liver and the first therapeutic response of MVI. There were no severe adverse events or radiation-induced hepatic complications. CONCLUSIONS: One-shot CDDP via HAI and RT were well tolerated and showed immediate and favorable control of MVI. Thus, this combination shows potential as a bridging therapy to systemic chemotherapy.

Potential benefits of volumetric modulated arc therapy to reduce the incidence of ≥ grade 2 radiation pneumonitis in radiotherapy for locally advanced non-small cell lung cancer patients.

BACKGROUND: The use of volumetric modulated arc therapy is gradually widespread for locally advanced non-small cell lung cancer. The purpose of this study was to identify the factors that caused ≥ grade 2 radiation pneumonitis and evaluate the impact of using volumetric modulated arc therapy on the incidence of ≥ grade 2 radiation pneumonitis by comparing three-dimensional conformal radiation therapy. METHODS: We retrospectively evaluated 124 patients who underwent radical radiotherapy for locally advanced non-small cell lung cancer in our institution between 2008 and 2019. The following variables were analysed to detect the factors that affected ≥ grade 2 radiation pneumonitis; age, sex, the presence of interstitial lung disease, pulmonary emphysema, tumour location, stage, PTV/lung volume, lung V20Gy, total dose, concurrent chemoradiotherapy, adjuvant immune checkpoint inhibitor, radiotherapy method. Radiation pneumonitis was evaluated using the common terminology criteria for adverse events (version 5.0). RESULTS: A total of 84 patients underwent three-dimensional conformal radiation therapy (3D-CRT group) and 40 patients underwent volumetric modulated arc therapy (VMAT group). The cumulative incidence of ≥ grade 2 radiation pneumonitis at 12 months was significantly lower in the VMAT group than in the 3D-CRT group (25% vs. 49.1%). The use of volumetric modulated arc therapy was a significant factor for ≥ grade 2 radiation pneumonitis (HR:0.32, 95% CI: 0.15-0.65, P = 0.0017) in addition to lung V20Gy (≥ 24%, HR:5.72 (95% CI: 2.87-11.4), P < 0.0001) and total dose (≥ 70 Gy, HR:2.64 (95% CI: 1.39-5.03), P = 0.0031) even after adjustment by multivariate analysis. CONCLUSIONS: We identified factors associated with ≥ grade 2 radiation pneumonitis in radiotherapy for patients with locally advanced non-small cell lung cancer. Volumetric modulated arc therapy has potential benefits to reduce the risk of ≥ grade 2 radiation pneumonitis.

Impact on liver position under breath-hold by computed tomography contrast agents in stereotactic body radiotherapy of liver cancer.

BACKGROUND: We investigated variations in liver position relative to the vertebral bone for liver cancer treated with stereotactic body radiation therapy under expiratory phase breath-hold (BH) for treatment with contrast-enhanced-computed tomography (CECT), non-CECT, and cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Seventeen consecutive patients using a contrast enhancement (CE) agent for the CT simulation session for this retrospective study were selected. The first computed tomography (CT) scan without the use of CE agent in the expiratory phase was used for treatment planning (pCT). The remaining three CT scans without a CE agent under expiratory phase BH were acquired successively without repositioning to evaluate the intra-fraction variation in liver position. Furthermore, a three-phase CT scan (arterial, portal, and late phases) accompanied by a CE agent under expiratory phase BH was acquired for target delineation. CBCT scans without the use of a CE agent under expiratory phase BH were acquired for treatment. Inter-fractional variations (non-CECT or CECT) in liver position were measured using the difference between CBCT and pCT or each 3 phase CECT images, respectively. RESULTS: The average ± standard deviations for intrafractional, non-CECT interfractional variations, and CECT interfractional variations were 1.0 ± 1.3, 2.5 ± 2.6, and 6.4 ± 6.4 mm, respectively, in the craniocaudal (CC) direction. Intra- and inter-fractional variations in liver position were relatively small for non-CECT. However, significant inter-fractional liver position variations in CECT were observed in the expiratory phase BH. The position of the liver should be carefully considered when applying CECT images for image-guided radiotherapy.

Biological dose-enhancement analysis with Monte Carlo simulation for Lipiodol for photon beams.

BACKGROUND: Previously, the physical dose-enhancement factor (DphysEF) enhancement was introduced. However, the dose enhancement considering the biological effectiveness was not shown. PURPOSE: The aim of the current study was to evaluate the biological dose-enhancement factor (DbioEF) by the dose rate and to compare the DphysEF and the DbioEF in Lipiodol for liver Stereotactic Body Radiation Therapy (SBRT). MATERIALS AND METHODS: Flattening-filter-free (FFF) 6-MV (6MVX) and 10MVX beams were delivered by TrueBeam. A virtual inhomogeneity phantom and a liver SBRT patient-treatment plan were used. The DphysEF and lineal energy distribution ( y ) distribution was calculated from Monte Carlo simulations. Using a microdosimetric-kinetic (MK) model that is estimated based on the linear-quadratic formula for Lipiodol using human liver hepatocellular cells (HepG2), the biological dose and biological dose enhancement factor (DbioEF) were calculated. The dose rate in the simulation was changed from 0.1 to 24 Gy/min. RESULTS: The DbioEF (DR:2Gy/min) and DphysEF with 10MVX FFF beam were 23.2% and 19.1% at maximum and 12.8% and 11.1% on average in the Lipiodol. In the comparison of the DbioEF between 0.1-24 Gy/min, the DbioEF was 21.2% and 11.1% with 0.1 Gy/min for 6MVX and 10 MVX, respectively. The DbioEF was larger than DEF for the 6MVX and 10MVX FFF beams. In clinical cases with the 10MVX FFF beam, the DbioEF and DphysEF in the Lipiodol region can increase the in-tumor dose by approximately 11% and 10%, respectively, without increasing the dose to normal tissue. CONCLUSIONS: The lower-energy and higher-dose-rate beams were contributed to the biological dose. The Lipiodol caused the enhancement of the physical dose and biological effectiveness. ADVANCES IN KNOWLEDGE: The biological dose enhancement (DbioEF) should be considered in the high-density material such as the Lipiodol.

Long-term outcome of stereotactic body radiotherapy for patients with small hepatocellular carcinoma.

AIM: To evaluate the long-term outcome of stereotactic body radiotherapy in patients with small hepatocellular carcinoma who were ineligible for resection or ablation therapies. METHODS: A total of 65 patients with 74 hepatocellular carcinomas (median tumor size 16 mm) were enrolled in the present study. They were treated with the prescribed dose of 48 Gy in four fractions at the isocenter. We extended the observation period and analyzed long-term outcomes, including overall survival, progression-free survival, local control, and various prognostic factors, in these patients. RESULTS: The median follow-up period was 41 months for all patients and 62 months for surviving patients. The 3- and 5-year overall survival rates were 56.3% (95% confidence interval, 44.1-68.5%) and 41.4% (95% confidence interval, 28.7-54.1%), respectively. The 3- and 5-year progression-free survival rates were 25.4% (95% confidence interval, 14.0-36.8%) and 10.6% (95% confidence interval, 1.5-19.8%), respectively. The 3- and 5-year local control rates were both 100% (95% confidence interval 100%). Liver toxicities exceeding grade 3 were observed in 15 patients (23.1%). The proportion of patients who had grade ≥3 toxicities did not increase. Adverse effects (grade ≤2) presented as significant prognostic factors of overall survival, while TNM stage (T1N0M0) was a significant prognostic factor of progression-free survival after multivariate analysis. CONCLUSIONS: Stereotactic body radiotherapy was effective for patients with small hepatocellular carcinomas who were ineligible for resection or ablation therapies. The incidence of grade ≥3 adverse effects did not increase, even after longer follow-up times.

Volumetric-Modulated Arc Therapy for Giant-Cell Tumor of Temporal Bone: An Illustrative Case Report.

Giant-cell tumor of the skull is extremely rare. Surgery is the main treatment for this disease, but not all cases are suitable for complete resection. In this report, we present the clinical features of a case of giant-cell tumor of temporal bone that demonstrated good outcome after radiation therapy (RT) using volumetric-modulated arc therapy (VMAT). The patient was a 55-year-old man with giant-cell tumor of temporal bone who received surgery as the first treatment. Three months after the initial surgery, the tumor regrew, and the patient received surgical resection again. Although second partial resection was undergone, it regrew. Therefore, 36 months after initial surgery, RT was conducted. The prescribed dose was 54 Gy in 1.8 Gy fractions using VMAT. The tumor began to shrink from 4 months after the initiation of RT and kept shrinking slowly and gradually. At the last follow-up, there was no evidence of local recurrence. There was no report about VMAT for giant-cell tumor of the skull, and no report revealed the radiographic details after recent radiation techniques. Therefore, this case report was meaningful in describing the details and response during and after VMAT for giant-cell tumor of temporal bone. The adjuvant RT using VMAT seemed to demonstrate a sufficient local control benefit without severe adverse effects in our case with giant-cell tumor of temporal bone.

Reirradiation Using 198Au Grain Brachytherapy for Recurrent Oral Cancer Cases Previously Treated by Definitive Radiotherapy.

BACKGROUND/AIM: We investigated treatment outcomes and complications during reirradiation of patients with oral cancers. PATIENTS AND METHODS: Six patients who received definitive radiotherapy for oral cancer as the initial treatment and brachytherapy for recurrence were included. Local control and overall survival rates, soft tissue and mandibular complications, and tooth extraction were investigated. RESULTS: The five-year local control and overall survival rates were 83.3% and 100%, respectively. The occurrence rate of grade 2 soft tissue and mandible complications was 33.3%, and the primary sites were the buccal mucosa and the floor of mouth. The positions of the extracted tooth in the two cases were adjacent to the tumor, and one case developed grade 2 complication of the mandible. CONCLUSION: During recurrence of the buccal mucosa and the floor of mouth cancers, reirradiation should be avoided considering mandibular complications. To avoid reirradiation-related complications, tooth extraction near the radiation field should be avoided.

Brachytherapy with 198Au grains for cancer of the floor of the mouth: relationships between radiation dose and complications.

OBJECTIVE: This study aimed to retrospectively evaluate the radiation dose and complications in soft tissue and mandible caused by 198Au grain brachytherapy alone or the combination with other modalities in patients with the cancer of the floor of the mouth. MATERIALS AND METHODS: Twelve patients with T1 (n = 5) and T2 (n = 7) squamous cell carcinoma of the floor of the mouth, who were treated with 198Au grain brachytherapy alone (n = 5) or the combination of external beam radiotherapy (EBRT) and/or chemotherapy and 198Au grain brachytherapy (n = 7) from January 2005 to December 2016, were included. The relationships between the radiation dose and the complications of the soft tissue or mandible were investigated. RESULTS: Seven of 12 patients had died. Of these 7 patients, one with T1 and 2 with T2 had died of the causes related to the cancer of the floor of the mouth. Two with T1 and 2 with T2 had died of other diseases. Two patients had grade 2 complications of the soft tissue and mandible. These patients were treated by the combination of EBRT and/or chemotherapy and 198Au grain brachytherapy and irradiated with 123 or 139 Gy in total dose, respectively. And one of these patients was treated by the chemotherapy in addition to EBRT. CONCLUSION: Our study showed that the combination of EBRT and 198Au grains brachytherapy for the floor of the mouth cancer patients might be associated with risks of developing complications of soft tissue ulcer and mandibular bone necrosis.

Temporal changes and risk factors for esophageal stenosis after salvage radiotherapy in superficial esophageal cancer following non-curative endoscopic submucosal dissection.

BACKGROUND AND PURPOSE: Radiotherapy (RT) has recently received increasing attention as an additional treatment for organ preservation after non-curative endoscopic submucosal dissection (ESD) in patients with superficial esophageal cancer. Esophageal stenosis is an adverse event related to RT after ESD that is not widely studied. The aim of this study was to investigate esophageal stenosis related to salvage RT in superficial esophageal cancer after non-curative ESD. MATERIALS AND METHODS: Fifty patients who received salvage RT after non-curative ESD at a single institution between 2011 and 2018 were included in this study. The Common Terminology Criteria for Adverse Events, version 5.0, was used to assess esophageal stenosis. Data were compared using Fisher's exact test. Statistical significance was set at P < 0.05. RESULTS: Median follow-up time was 48 months (range, 12-95 months). Grade 2 and 3 esophageal stenosis were observed in 17 (34%), and 3 patients (6%), respectively. The frequency of grade 2 or worse esophageal stenosis decreased over time (before RT, 6 months, 1 year, and 2 years after RT: 16 (32%), 13 (26%), 10 (20%), and 6 (12%) patients, respectively). Only one patient required endoscopic balloon dilation (EBD) 1 year after RT. All grade 3 esophageal stenosis improved grade 2 or less by EBD. In univariate analysis, only tumor location was a significant risk factor for grade 3 esophageal stenosis. CONCLUSIONS: Esophageal stenosis, after salvage RT in patients with esophageal cancer who received non-curative ESD, improved naturally or after EBD; only a few cases required long-term EBD.

Investigating the displacement of radio-active sources during gold-198 grain brachytherapy for hospitalized oral cancer patients.

Purpose: This study aimed to investigate status of displacement of gold-198 (198Au) grains in patients with oral cancers as well as factors and countermeasures for the displacement of 198Au grains. Material and methods: The present study included 34 patients with oral cancers, who were exclusively treated with 198Au grain brachytherapy between 2013 and 2019. Timing and duration of the 198Au grain displacement from the oral cavity and reduction in radiation dose were estimated. Location of the displaced grain was classified as either inside or outside of gross tumor volume. Number and location of the displacement of 198Au grains, primary lesion, and growth type were evaluated. Results: Of the 34 patients included in this study, 198Au grains were displaced in 4 patients (11.8%) during hospitalization. A total of 5 grains (1.4%) were displaced out of an overall count of 367 grains implanted in these 34 patients. Of the four patients who experienced displacement of 198Au grains, three had tongue cancer, and one had lip cancer. All four patients whose grains were displaced had superficial lesions. Conclusions: When performing brachytherapy with 198Au grains for superficial lesions on the tongue or lips, care should be taken to avoid grain displacement.

Development of a radiomics and machine learning model for predicting occult cervical lymph node metastasis in patients with tongue cancer.

OBJECTIVE: We aimed to develop a predictive model for occult cervical lymph node metastasis in patients with tongue cancer using radiomics and machine learning from pretreatment contrast-enhanced computed tomography. STUDY DESIGN: This study included 161 patients with tongue cancer who received local treatment. Computed tomography images were transferred to a radiomics platform. The volume of interest was the total neck node level, including levels Ia, Ib, II, III, and IVa at the ipsilateral side, and each neck node level. The dimensionality of the radiomics features was reduced using least absolute shrinkage and selection operator logistic regression analysis. We compared 5 classifiers with or without the synthetic minority oversampling technique (SMOTE). RESULTS: For the analysis at the total neck node level, random forest with SMOTE was the best model, with an accuracy of 0.85 and an area under the curve score of 0.92. For the analysis at each neck node level, a support vector machine with SMOTE was the best model, with an accuracy of 0.96 and an area under the curve score of 0.98. CONCLUSIONS: Predictive models using radiomics and machine learning have potential as clinical decision support tools in the management of patients with tongue cancer for prediction of occult cervical lymph node metastasis.

Predicting the Local Response of Esophageal Squamous Cell Carcinoma to Neoadjuvant Chemoradiotherapy by Radiomics with a Machine Learning Method Using 18F-FDG PET Images.

BACKGROUND: This study aimed to propose a machine learning model to predict the local response of resectable locally advanced esophageal squamous cell carcinoma (LA-ESCC) treated by neoadjuvant chemoradiotherapy (NCRT) using pretreatment 18-fluorodeoxyglucose positron emission tomography (FDG PET) images. METHODS: The local responses of 98 patients were categorized into two groups (complete response and noncomplete response). We performed a radiomics analysis using five segmentations created on FDG PET images, resulting in 4250 features per patient. To construct a machine learning model, we used the least absolute shrinkage and selection operator (LASSO) regression to extract radiomics features optimal for the prediction. Then, a prediction model was constructed by using a neural network classifier. The training model was evaluated with 5-fold cross-validation. RESULTS: By the LASSO analysis of the training data, 22 radiomics features were extracted. In the testing data, the average accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve score of the five prediction models were 89.6%, 92.7%, 89.5%, and 0.95, respectively. CONCLUSIONS: The proposed machine learning model using radiomics showed promising predictive accuracy of the local response of LA-ESCC treated by NCRT.

Hydrogel spacer shrinkage during external-beam radiation therapy following low-dose-rate brachytherapy for high-risk prostate cancer: a case series.

BACKGROUND: Few studies have assessed hydrogel spacer shrinkage during external-beam radiation therapy following brachytherapy for localized high-risk prostate cancer. This case presentation evaluated the changes in hydrogel spacer appearance by magnetic resonance imaging during external-beam radiation therapy after brachytherapy for prostate cancer and analyzed the effect of this shrinkage on the dose distribution in four cases. CASE PRESENTATION: In all cases, we implanted 125I sources using a modified peripheral loading pattern for seed placement. The prescribed dose for each implant was 110 Gy. After delivering the sources, a hydrogel spacer was injected. All cases underwent external-beam radiation therapy approximately 1-2 months after brachytherapy. The prescribed dose of external-beam radiation therapy was 45 Gy in 1.8-Gy fractions. Magnetic resonance imaging was performed for evaluation on the day following seed implantation (baseline), at external-beam radiation therapy planning, and during external-beam radiation therapy. The median hydrogel spacer volume was 16.2 (range 10.9-17.7) cc at baseline, 14.4 (range, 9.4-16.1) cc at external-beam radiation therapy planning, and 7.1 (range, 2.0-11.4) cc during external-beam radiation therapy. The hydrogel spacer volume during external-beam radiation therapy was significantly lower than that at external-beam radiation therapy planning. The rectum V60-80 (rectal volume receiving at least 60-80% of the prescribed dose of external-beam radiation therapy) during external-beam radiation therapy was significantly higher than that at external-beam radiation therapy planning. CONCLUSIONS: The potential reduction in hydrogel spacer size during external-beam radiation therapy following brachytherapy can lead to unexpected irradiation to the rectum. This case presentation would be helpful for similar cases.

Long-term results of definitive chemoradiotherapy for unresectable locally advanced esophageal squamous cell carcinoma.

PURPOSE: The present study aimed to evaluate the long-term results of definitive chemoradiotherapy (CRT) for unresectable locally advanced esophageal squamous cell carcinoma (LA-ESCC). MATERIALS AND METHODS: We analyzed eighty patients with unresectable LA-ESCC, who underwent definitive CRT between 2001 and 2014. The 5-year overall survival (OS), cause-specific survival (CSS), and progression-free survival (PFS) rates were calculated, and we investigated the prognostic factors and adverse events. RESULTS: The median age was 66 years (range, 41-83 years). Histologically, all patients had squamous cell carcinoma. The most common tumor site was the middle thoracic esophagus in 43 (54%) patients. According to the eighth edition of the Union for International Cancer Control TNM classification, sixty-six patients (83%) had T4 disease, 59 (74%) had regional lymph node (LN) metastases, and 35 (44%) had distant LN metastases beyond the regional LN (M1 LYM) disease. Forty-five (56%) and 35 (44%) patients belong to clinical stages IVA and IVB, respectively. The median follow-up period for survivors was 86 months. The 5-year OS, CSS, and PFS rates were 20.2%, 25.7%, and 18.4%, respectively. On univariate analysis, only the performance status score was significantly associated with better overall survival (p = 0.026). Grade 3 or higher late adverse events were observed in 12 (15%) patients, and these included cardiopulmonary adverse events in 6 (8%) patients. Treatment-related death occurred in 3 (4%) patients. CONCLUSION: We showed the long-term results of definitive CRT for unresectable LA-ESCC. The survivals are still poor and new treatment strategies need to be developed.

Treatment outcomes of real-time intraoral sonography-guided implantation technique of 198Au grain brachytherapy for T1 and T2 tongue cancer.

It is often challenging to determine the accurate size and shape of oral lesions through computed tomography (CT) or magnetic resonance imaging (MRI) when they are very small or obscured by metallic artifacts, such as dental prostheses. Intraoral ultrasonography (IUS) has been shown to be beneficial in obtaining precise information about total tumor extension, as well as the exact location and guiding the insertion of catheters during interstitial brachytherapy. We evaluated the role of IUS in assessing the clinical outcomes of interstitial brachytherapy with 198Au grains in tongue cancer through a retrospective medical chart review. The data from 45 patients with T1 (n = 21) and T2 (n = 24) tongue cancer, who were mainly treated with 198Au grain implants between January 2005 and April 2019, were included in this study. 198Au grain implantations were carried out, and positioning of the implants was confirmed by IUS, to ensure that 198Au grains were appropriately placed for the deep border of the tongue lesion. The five-year local control rates of T1 and T2 tongue cancers were 95.2% and 95.5%, respectively. We propose that the use of IUS to identify the extent of lesions and the position of implanted grains is effective when performing brachytherapy with 198Au grains.

Efficacy and tolerability of preoperative chemoradiotherapy with S-1 alone for locally advanced rectal cancer.

Preoperative chemoradiotherapy with capecitabine or 5-fluorouracil is a standard treatment for locally advanced rectal cancer (LARC). S-1, a prodrug of 5-fluorouracil, is a candidate for this chemoradiotherapy regimen in Japan; however, treatment outcomes after S-1 treatment alone are not clear. This study aimed to assess the efficacy and tolerability of preoperative chemoradiotherapy with S-1 alone for LARC. We retrospectively evaluated 54 LARC patients who underwent preoperative chemoradiotherapy with S-1 alone in our institution between 2005 and 2017. The clinical tumor stage was cT2-3 in 31 patients and cT4 in 23 patients, and lymph node metastases were clinically evident in 31 patients. S-1, at a dose of 80 mg/m2/day, was orally administered during radiotherapy. A total dose of 45-50.4 Gy was delivered in 25-28 fractions (median: 50.4 Gy). Surgical resections were scheduled 6-10 weeks after chemoradiotherapy completion. The 3- and 5-year overall survival rates were 92.4 and 72.8%, respectively, with a median follow-up time of 51 months. The 3- and 5-year local control rates were 96.2 and 85.9%, respectively. A pathological complete response was observed in 7 patients (13.0%) at the time of surgery. Ten patients (18.5%) had grade 3 acute toxicities and 5 patients (9.3%) had grade 3 late toxicities. No grade 4 or 5 toxicities were observed. Preoperative chemoradiotherapy with S-1 alone followed by total mesorectal excision resulted in a low incidence of toxicities and comparable clinical results. Therefore, S-1 alone can be a treatment option for preoperative chemoradiotherapy in LARC patients.

Effectiveness of robust optimization in volumetric modulated arc therapy using 6 and 10 MV flattening filter-free beam therapy planning for lung stereotactic body radiation therapy with a breath-hold technique.

We investigated the feasibility of a robust optimization with 6 MV X-ray (6X) and 10 MV X-ray (10X) flattening filter-free (FFF) beams in a volumetric modulated arc therapy (VMAT) plan for lung stereotactic body radiation therapy (SBRT) using a breath-holding technique. Ten lung cancer patients were selected. Four VMAT plans were generated for each patient; namely, an optimized plan based on the planning target volume (PTV) margin and a second plan based on a robust optimization of the internal target volume (ITV) with setup uncertainties, each for the 6X- and 10X-FFF beams. Both optimized plans were normalized by the percentage of the prescription dose covering 95% of the target volume (D95%) to the PTV (1050 cGy × 4 fractions). All optimized plans were evaluated using perturbed doses by specifying user-defined shifted values from the isocentre. The average perturbed D99% doses to the ITV, compared to the nominal plan, decreased by 369.1 (6X-FFF) and 301.0 cGy (10X-FFF) for the PTV-based optimized plan, and 346.0 (6X-FFF) and 271.6 cGy (10X-FFF) for the robust optimized plan, respectively. The standard deviation of the D99% dose to the ITV were 163.6 (6X-FFF) and 158.9 cGy (10X-FFF) for the PTV-based plan, and 138.9 (6X-FFF) and 128.5 cGy (10X-FFF) for the robust optimized plan, respectively. Robust optimized plans with 10X-FFF beams is a feasible method to achieve dose certainty for the ITV for lung SBRT using a breath-holding technique.

Evaluation of interbreath-hold lung tumor position reproducibility with vector volume histogram using the breath-hold technique.

Tumor geometric reproducibility for lung stereotactic body radiotherapy (SBRT) is an important issue in the breath-hold (BH) technique. We investigated the inter-BH reproducibility of the tumor position in expiratory BH using our proposed vector volume histogram (VVH) method. Subjects comprising 14 patients with lung cancer who were treated with lung SBRT under expiratory BH conditions were monitored by the Abches system. Multiple computed tomography (CT) scans were performed to evaluate the inter-BH reproducibility of the tumor position at the expiratory BH in the simulation session. Gross tumor volume was delineated by a physician. Deformable image registration was used to deform the images from the 3 expiratory BH-CTs to the treatment planning expiratory BH-CT. To evaluate the inter-BH reproducibility of the tumor positions, we measured the largest motion extent within the organ of 3 dimensions (left-right, LR; anterior-posterior, AP; cranio-caudal, CC) and a 3D vector using the VVH method. The average and standard deviations of the inter-BH reproducibility of the tumor position in the LR, AP, and CC directions, and the 3D vector were 1.7 ± 0.5, 2.0 ± 0.7, 2.1 ± 0.7, and 2.7 ± 0.7 mm, respectively. Ten patients exhibited inter-BH displacements of the lung tumor >3 mm in the 3D vector. No displacement >5 mm was observed in any direction for all patients. Our study indicated that the inter-BH variation of the tumor position was small for lung cancer patients, using the Abches system and the VVH method.

A Single Institution's Experience of Definitive Radiotherapy Using Volumetric-modulated Arc Therapy for Hypopharyngeal Cancers.

BACKGROUND/AIM: The present study aimed to analyze the treatment outcome after definitive radiotherapy (dRT) using volumetric-modulated arc therapy (VMAT) in patients with hypopharyngeal cancer (HPC), including an examination of late toxicities. PATIENTS AND METHODS: A total of 62 patients with HPC, who underwent dRT using VMAT, were analyzed. Overall survival (OS), progression-free survival (PFS), laryngoesophageal dysfunction-free survival (LEDFS), and locoregional control (LRC) were calculated. RESULTS: The median follow-up period was 49 months. The 3- and 5-year OS, PFS, LEDFS, and LRC rates were 77% and 60%, 61% and 56%, 66% and 53%, and both 79%, respectively. Regarding late toxicities, 11 (17.7%) patients developed grade ≥2 late toxicity. Grade 3 dysphagia was observed in 4 (6.5%) patients, and grade 2 xerostomia in 6 (9.7%). CONCLUSION: VMAT was an effective treatment for HPC, with a low incidence of late toxicities.