Recent advances in intensity modulated radiotherapy and proton therapy for esophageal cancer

Knowledge domains and emerging trends in radiotherapy in oesophageal cancer from 2004 to 2023: a bibliometric analysis and visualization study

Esophageal cancer (EC) is a malignant tumour with high morbidity and mortality rates. Recent studies have shown that much progress has been made in the research of radiotherapy in EC. This study aims to provide a comprehensive overview of the knowledge structure and research hotspots of radiotherapy in EC through bibliometrics. Publications related to radiotherapy in EC from 2014 to 2023 were searched on the web of science core collection database. VOSviewers, CiteSpace and R package 'bibliometrix' were used to conduct this bibliometric analysis. In total, 4258 articles from 76 countries led by China and the USA were included. The Chinese Academy of Medical Sciences-Peking Union Medical College has the highest number of publications. International Journal of Radiation Oncology Biology Physics is the most popular journal and also the most co-cited journal in this field. These publications come from 21 972 authors among which Liao Zhongxing had published the most papers and Cooper JS was co-cited most often. Neoadjuvant chemoradiotherapy and strategies based on it are the main topics in this research field. 'IMRT' and 'immunotherapy' are the primary keywords of emerging research hotspots. This is a bibliometric study that comprehensively summarizes the research trends and developments of radiotherapy in EC. This information identifies recent research frontiers and hot directions, which will provide a reference for scholars studying radiotherapy in EC.

A Review of Advances in Radiotherapy in the Setting of Esophageal Cancers

Esophageal cancer is the eighth most common cancer worldwide and is the sixth most common cause of cancer-related mortality. The paradigm has shifted to include a multimodality approach with surgery, chemotherapy, targeted therapy (including immunotherapy), and radiation therapy. Advances in radiotherapy through techniques such as intensity modulated radiotherapy and proton beam therapy have allowed for the more dose homogeneity and improved organ sparing. In addition, recent studies of targeted therapies and predictive approaches in patients with locally advanced disease provide clinicians with new approaches to modify multimodality treatment to improve clinical outcomes.

Volumetric modulated arc therapy (VMAT): a review of clinical outcomes—what is the clinical evidence for the most effective implementation?

Modern conformal radiation therapy using techniques such as modulation, image guidance and motion management have changed the face of radiotherapy today offering superior conformity, efficiency, and reproducibility to clinics worldwide. This review assesses the impact of these advanced radiotherapy techniques on patient toxicity and survival rates reported from January 2017 to September 2020. The main aims are to establish if dosimetric and efficiency gains correlate with improved survival and reduced toxicities and to answer the question ‘What is the clinical evidence for the most effective implementation of VMAT?’. Compared with 3DCRT, improvements have been reported with VMAT in prostate, locally advanced cervical carcinoma and various head and neck applications, leading to the shift in technology to VMAT. Other sites such as thoracic neoplasms and nasopharyngeal carcinomas have observed some improvement with VMAT although not in line with improved dosimetric measures, and the burden of toxicity and the incidence of cancer related deaths remain high, signaling the need to further mitigate toxicity and increase survival. As technological advancement continues, large randomised long-term clinical trials are required to determine the way-forward and offer site-specific recommendations. These studies are usually expensive and time consuming, therefore utilising pooled real-world data in a prospective nature can be an alternative solution to comprehensively assess the efficacy of modern radiotherapy techniques.

Research Value of Intensity Modulated Radiation Therapy in Alleviating Parotid Gland Function Injury in Patients with Stage N0 Nasopharyngeal Carcinoma from Physical and Dosimetric Aspects

Objective

To study the feasibility of intensity modulated radiation therapy (IMRT) for stage N₀ nasopharyngeal carcinoma (NPC) and its parotid gland (PG) function preservation from physical and dosimetric aspects.

Methods

All the clinical data of 77 patients with pathologically confirmed T_1-4N₀M₀ NPC who received radiotherapy between July 2017 and October 2019 in the Radiotherapy Center of Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University were analyzed retrospectively. Three-dimensional conformal radiotherapy (3D-CRT) and IMRT were used in 35 and 42 cases, respectively. The treatment efficiency and the dosimetry differences of the PG in the intensity modulation plan were compared between groups. Quantitative monitoring of 99mTc radionuclide imaging of PG was performed before, at the end of, and 3, 6, and 12 months after radiotherapy. The degree of PG function injury and xerostomia was compared between groups at the end of radiotherapy and 12 months later.

Results

Higher minimal, maximal, and average irradiation doses of PG were determined in 3D-CRT-treated patients compared with IMRT-treated cases (P < 0.05). Compared with before radiotherapy, the PG uptake index (UI) and excretion index (EI) of both cohorts of patients decreased to varying degrees at the end of radiotherapy, with PG function injury and xerostomia symptoms observed in all cases but with no obvious difference between groups (P > 0.05). To a certain extent, the PG function recovered and the xerostomia symptoms relieved in both groups 12 months after radiotherapy, with better improvements in IMRT group versus 3D-CRT group.

Conclusion

IMRT has similar short-term efficacy to 3D-CRT in treating patients with stage N₀ NPC, but it can effectively reduce the dose of PG radiotherapy and protect the PG function on the premise of ensuring sufficient tumor coverage and dose, showing certain dosimetry advantages.

Radiobiological Comparison of Acuros External Beam and Anisotropic Analytical Algorithm on Esophageal Carcinoma Radiotherapy Treatment Plans

Objective

The present study aimed to investigate the dose differences and radiobiological assessment between Anisotropic Analytical Algorithm (AAA) and Acuros External Beam (AXB) with its 2 calculation models, namely, dose-to-water (AXB-Dw) and dose-to-medium (AXB-Dm), on esophageal carcinoma radiotherapy treatment plans.

Materials and methods

The AXB-Dw and AXB-Dm plans were generated by recalculating the initial 66 AAA plans using the AXB algorithm with the same monitor units and beam parameters as those in the original plan. The dosimetric and radiobiological assessment parameters were calculated for the planning target volume (PTV) and organs at risk (OARs). The gamma agreement for the PTV and the correlation between it and the volume of the air cavity and bone among the different algorithms were compared simultaneously. The dose discrepancy between the theoretical calculation and treatment planning system (TPS) when switching from AXB-Dm to AXB-Dw was analyzed according to the composition of the structures.

Results

The PTV dose of AXB-Dm plans was significantly smaller than that of the AAA and AXB-Dw plans (P < .05), except for D₂. The difference values for AAA vs AXB-Dm (∆D_{x,(AAA-AXB,Dm)}) and AXB-Dw vs AXB-Dm (∆D_{x,(AXB,Dw-AXB,Dm)}) were 1.94% [1.27%, 2.64%] and 1.95% [1.56%, 2.27%], respectively. For the spinal cord and heart, there were obvious differences between the AAA vs AXB-Dm (spinal cord: 1.15%, heart: 2.89%) and AXB-Dw vs AXB-Dm (spinal cord: 1.88%, heart: 3.25%) plans. For the lung, the differences between AAA vs AXB-Dm and AAA vs AXB-Dw were significantly larger than those of AXB-Dm vs AXB-Dw. Compared to the case of AAA and AXB-Dw, the decrease in biologically effective dose (BED¹⁰, αβ=10 ) of AXB-Dm due to dose non-uniformity exceeded 6.5%, even for a small σ. The average values of equivalent uniform dose in the AAA, AXB-Dw, and AXB-Dm plans were 52.03±.39 Gy, 52.24 ± .81 Gy, and 51.13 ± .47 Gy, respectively. The tumor control probability (TCP) results for PTV in the AAA, AXB-Dw, and AXB-Dm plans were 62.29 ± 1.57%, 62.82 ± 1.69%, and 58.68±1.88%, respectively. With the 2%/2 mm and 3%/3 mm acceptance criteria, the mean values of  ΔγAAAAXB−Dw, ΔγAAAAXB−Dm, and  ΔγAXB−DmAXB−Dw were 87.24, 63.3, and 64.81% vs 97.86, 91.77, and 89.25%, respectively. The dose discrepancy between the theoretical calculation and TPS when switching from AXB-Dm to AXB-Dw was approximately 1.63%.

Conclusions

The AAA and AXB-Dw algorithms overestimated the radiobiological parameters when the tumor particularly consisted of nonuniform tissues. A relatively small dose difference could cause a significant reduction in the corresponding TCP. Dose distribution algorithms should be carefully chosen by physicists and oncologists to improve tumor control, as well as to optimize OARs protection.

Modeling the risk of radiation pneumonitis in esophageal squamous cell carcinoma treated with definitive chemoradiotherapy

BACKGROUND

To develop and validate a nomogram for the prediction of symptomatic radiation pneumonitis (RP) in patients with esophageal squamous cell carcinoma (ESCC) who received definitive concurrent chemoradiotherapy.

METHODS

Clinical factors, dose-volume histogram parameters, and pulmonary function parameters were collected from 402 ESCC patients between 2010 and 2017, including 321 patients in the primary cohort and 81 in the validation cohort. The end-point was the occurrence of symptomatic RP (grade ≥ 2) within the first 12 months after radiotherapy. Univariate and multivariate logistic regression analyses were applied to evaluate the predictive value of each factor for RP. A prediction model was generated in the primary cohort, which was internally validated to assess its performance.

RESULTS

In the primary cohort, 31 patients (9.7%) experienced symptomatic RP. Based on logistic regression model, patients with larger planning target volumes (PTVs) or higher lung V₂₀ had a higher predictive risk of RP, whereas the overall risk was substantially higher for three-dimensional conformal radiotherapy (3DCRT) than intensity-modulated radiotherapy. On multivariate analysis, independent predictive factors for RP were smoking history (P = 0.035), radiotherapy modality (P < 0.001), PTV (P = 0.039), and lung V₂₀ (P < 0.001), which were incorporated into the nomogram. The areas under the receiver operating characteristic curve of the nomogram in the primary and validation cohorts were 0.772 and 0.900, respectively, which were superior to each predictor alone.

CONCLUSIONS

Non-smoking status, 3DCRT, lung V₂₀ (> 27.5%), and PTV (≥ 713.0 cc) were significantly associated with a higher risk of RP. A nomogram was built with satisfactory prediction ability.

Epidemiology, Diagnosis, Staging and Multimodal Therapy of Esophageal and Gastric Tumors

Gastric and esophageal tumors are diverse neoplasms that involve mucosal and submucosal tissue layers and include squamous cell carcinomas, adenocarcinomas, spindle cell neoplasms, neuroendocrine tumors, marginal B cell lymphomas, along with less common tumors. The worldwide burden of esophageal and gastric malignancies is significant, with esophageal and gastric cancer representing the ninth and fifth most common cancers, respectively. The approach to diagnosis and staging of these lesions is multimodal and includes a combination of gastrointestinal endoscopy, endoscopic ultrasound, and cross-sectional imaging. Likewise, therapy is multidisciplinary and combines therapeutic endoscopy, surgery, radiotherapy, and systemic chemotherapeutic tools. Future directions for diagnosis of esophageal and gastric malignancies are evolving rapidly and will involve advances in endoscopic and endosonographic techniques including tethered capsules, optical coherence tomography, along with targeted cytologic and serological analyses.

A nomogram for the predicting of survival in patients with esophageal squamous cell carcinoma undergoing definitive chemoradiotherapy

Background

Definitive chemoradiotherapy (dCRT) is widely accepted for esophageal squamous cell carcinoma (ESCC), although the outcomes can vary. Therefore, we aimed to develop a nomogram for the pre-treatment prediction of survival after dCRT for ESCC.

Methods

This retrospective study evaluated 204 patients (169 patients in a primary cohort and 35 patients in a validation cohort) who received dCRT for ESCC between July 2013 and June 2017.

Results

Pre-treatment parameters that predicted long-term survival in this setting were body mass index (BMI), absolute lymphocyte count (ALC), neutrophil-to-lymphocyte ratio (NLR), wall thickness, concurrent chemoradiotherapy, radiotherapy modality, and American Joint Committee on Cancer (AJCC) stage. The nomogram incorporated these factors and provided C-index values of 0.691 [95% confidence interval (CI): 0.641-0.740] in the primary cohort and 0.816 (95% CI: 0.700-0.932) in the validation cohort. The calibration curve analysis revealed that the nomogram had good ability to predict 2-year progression-free survival (PFS). The nomogram also performed better than the AJCC staging system by the C-index values (0.691 vs. 0.560) and the area under the curve values (0.702 vs. 0.576). Decision curve analysis (DCA) also indicated that the nomogram had better clinical utility.

Conclusions

These results suggest that pre-treatment parameters may help predict the efficacy of dCRT for ESCC. Furthermore, as the nomogram provided better prognostic accuracy than the AJCC staging system, the nomogram may be useful in clinical practice for prognostication among patients who are going to receive dCRT for ESCC.

Hypoxic tumour cell-derived exosomal miR-340-5p promotes radioresistance of oesophageal squamous cell carcinoma via KLF10

Background

Radiotherapy resistance is a major obstacle in the treatment of oesophageal squamous cell carcinoma (OSCC). Hypoxia is a critical cause of radioresistance. However, the communication between hypoxic cells and aerobic cells via exosomes during the transfer of radiation resistance remains unclear.

Methods

Exo-miR-340-5p levels were analysed by RNA-seq and qRT-PCR. We co-cultured OSCC cells with isolated normoxic and hypoxic exosomes to study their impact on radiosensitivity. We used a specific exo-miR-340-5p mimic and knock-down retrovirus to explore the role of this miRNA in the transfer of radioresistance from hypoxic to normoxic cells. Dual-luciferase reporter and RIP assays were used to verify KLF10 as a putative target of miR-340-5p. Several in vitro assays were conducted and xenograft models were established to investigate the effect of exo-miR-340-5p on OSCC radiosensitivity. The plasma exo-miR-340-5p levels in OSCC patients were analysed to study the clinical value of this parameter.

Results

Hypoxic exosomes alleviated radiation-induced apoptosis and accelerated DNA damage repair. miR-340-5p was highly expressed in hypoxic exosomes and was transferred into normoxic cells, where it induced radioresistance. Overexpression of miR-340-5p in normoxic OSCC cells mimicked the radioresistance of cells co-cultured with hypoxic exosomes. Knockdown of miR-340-5p in hypoxic exosomes reversed the radioresistance effect, indicating that exo-miR-340-5p is critical for hypoxic EV-transferred radioresistance. KLF10 was identified as the direct target of miR-340-5p. Moreover, metformin was found to increase the expression of KLF10 and enhance the radiosensitivity of OSCC. Higher levels of miR-340-5p in the plasma exosomes from OSCC patients are related to a poorer radiotherapy response and prognosis.

Conclusions

Hypoxic tumour cell-derived exosomal miR-340-5p confers radioresistance in OSCC by targeting KLF10/UVRAG, suggesting that miR-340-5p could be a potential biomarker and therapeutic target for the enhancement of radiosensitivity in OSCC. Metformin can increase KLF10 expression, which ameliorates the radioresistance induced by exo-miR-340-5p transfer. Therefore, metformin could be further investigated as a therapeutic option for the treatment of OSCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01834-9.

LncRNA MAGI2-AS3 Overexpression Sensitizes Esophageal Cancer Cells to Irradiation Through Down-Regulation of HOXB7 via EZH2

Background

Accumulating evidence has suggested that aberrant expression of long non-coding RNAs (lncRNAs) may contribute to cancer progression in association with radioresistance. The current study aimed to identify the potential role of lncRNA MAGI2-AS3 and the underlying mechanism in its regulation of the radio-sensitivity of esophageal cancer cells.

Methods and Results

Initially, we detected high expression of HOXB7 from microarray-based gene expression profiling of esophageal cancer. Then, we identified the interactions among MAGI2-AS3, HOXB7, and EZH2 by dual-luciferase reporter gene assay, RNA pull-down assay, RIP assay and ChIP assay. HOXB7 was highly-expressed, while MAGI2-AS3 was poorly-expressed in esophageal cancer tissues and cells. The effect of MAGI2-AS3 and HOXB7 on esophageal cancer cell proliferation and apoptosis as well as tumorigenicity of radioresistant cells was examined by gain- and loss-of-function experiments. Interestingly, MAGI2-AS3 down-regulated HOXB7 through interaction with EZH2, which promoted cell apoptosis and inhibited proliferation and radio-resistance. Besides, down-regulation of MAGI2-AS3 exerted a promoting effect on these malignant phenotypes.

Conclusion

Taken together, our results reveal the potential role of MAGI2-AS3 over-expression in controlling esophageal cancer resistance to radiotherapy by down-regulating HOXB7, this providing a candidate biomarker for resistance to radiotherapy.

Competing risk nomogram to predict cancer-specific survival in esophageal cancer during the intensity-modulated radiation therapy era: A single institute analysis

The present study aimed to investigate the probability of cancer-associated mortality of patients with esophageal cancer undergoing intensity-modulated radiation therapy (IMRT), and to establish a competing risk nomogram to predict the esophageal cancer-specific survival (EC-SS) of these patients. A total of 213 patients with EC who underwent IMRT between January 2014 and May 2017 were selected to establish nomograms according to Fine and Gray's competing risk analysis. Predictive accuracy and discriminative ability of the model were determined using the concordance index (C-index), calibration curves and the area under receiver operating characteristic curves. Decision tree analysis was also constructed for patient grouping. With a median follow-up of 19 months (range, 3–50), the 2-year EC-specific mortality (EC-SM) and the non-esophageal cancer specific mortality (NEC-SM) of the cohort were 35.4 and 3.51%, respectively. Furthermore, an elevated 2-year EC-SM was observed in patients with tumor length ≥4.5 cm compared with patients with tumor length <4.5 cm (45.8% vs. 21.4%; P<0.001), patients with non-squamous cell carcinoma compared with patients with squamous cell carcinoma (49.9 vs. 33.7%; P=0.025) and patients with N3 stage (43.2%; P=0.005). The 2-year NEC-SM of patients with tumor length ≥4.5 cm was 6% vs. 0% in patients with tumor length <4.5 cm (P=0.016). Three independent risk factors for survival, including tumor length, histological type and N stage, were integrated to build competing nomograms for the EC-SS model (C-index=0.72; 95% confidence interval, 0.66–0.77). In addition, the nomograms displayed better discrimination power than the 7th edition of the Tumor-Node-Metastasis staging system for predicting EC-SS (area under the curve=0.707 vs. 0.634). Furthermore, the results from the classification tree analysis demonstrated that N stage was the initial node and that primary tumor length was a determinant for EC-SM in these patients. In conclusion, NEC-SM represented a competing event for patients with EC with a tumor length ≥4.5 cm. The competing risk nomograms may therefore be considered as convenient individualized predictive tools for cancer-specific survival in patients with EC undergoing IMRT treatment.

A technique to reduce skin toxicity in radiotherapy treatment planning for esophageal cancer

PURPOSE

To demonstrate a specific skin dose limiting technique in radiotherapy treatment planning for esophageal cancer and carry out a comparative analysis combining with clinical cases.

MATERIAL AND METHODS

Thirty patients with cervical and upper thoracic esophageal carcinoma previously treated in our institution were selected. A treatment plan had been finished previously according to the planning parameters directives from physician and delivered for each patient. In this study, we copied the previously delivered plans in radiotherapy treatment planning system and converted a low dose level (usually 5Gy) to a skin dose limiting structure (SDLS), then we set the objective functions of the SDLS in the Pinnacle Inverse Planning module and re-optimize the plans to reduce the skin doses. Finally, we compared the dose distribution and other parameters of target volume and organs at risk (OARs) between the old plans and the new plans.

RESULTS

There was no significant difference in most of OARs sparing. However, for all plans, the maximum dose to the SDLS decreased from 6145.90 ± 416.96 cGy to 5562.09 ± 616.69 cGy with maximum difference of 1361.30 cGy (P < 0.05), the percentage volume of 40Gy received by the SDLS decreased from (10.20 ± 6.36)% to (5.46 ± 4084)% with maximum difference of 9.89% (P < 0.05). For the target volume, there was no significant difference in the average dose and maximum dose, the approximate minimum dose to the target volume decreased from 5711.28 ± 164.61 cGy to 5584.93 ± 157.70 cGy (P < 0.05), the conformal index and homogeneity index of the target volume were hardly changed.

CONCLUSION

In radiotherapy treatment planning for esophageal cancer patients, the skin dose can be significantly reduced using the skin dose limiting technique, and the impact on the dose to target volume and OARs is little, this technique can be used in most radiotherapy treatment planning.

Comparing efficacy of high-dose rate brachytherapy versus helical tomotherapy in the treatment of cervical cancer

Objective

Boost radiation using brachytherapy (BT) is a standard treatment for local disease control in concomitant chemoradiation therapy (CCRT) for advanced cervical cancer. However, it is associated with gastrointestinal and genitourinary complications. Hence, this study investigates the feasibility of helical tomotherapy (HT) as an alternative to BT.

Methods

Medical records of patients who underwent CCRT between 2000 and 2017 at a single institution were retrospectively reviewed. Patients with stage IIB–IVA cancers were selected based on the 2009 criteria of The International Federation of Gynaecology and Obstetrics. External beam radiation combined with chemotherapy was followed by either BT or HT. The propensity score matching of both groups was calculated using logistic regression analysis. Disease outcomes and treatment-related adverse events were compared between the 2 groups.

Results

The matched population included 70 BT patients and 35 HT patients. The 5-year progression-free survival rates for BT and HT were 72.6% and 72.5%, respectively (p=0.721). There was no difference in the overall survival rate between the two groups (p=0.203). The presence of acute and chronic gastrointestinal complications was also similar between the groups (p=0.460 and p=0.563, respectively). The chronic genitourinary toxicities were also comparable (p=0.105).

Conclusions

HT boost treatment showed comparable disease outcomes with those observed with conventional BT in patients with advanced cervical cancer. HT could be a complementary boost protocol as a single modality or hybrid with BT in selected patients. Further studies with longer follow-up periods are warranted to confirm long-term outcomes.

Dynamic changes in T-cell subsets and C-reactive protein after radiation therapy in lung cancer patients and correlation with symptomatic radiation pneumonitis treated with steroid therapy

Objectives

To investigate relationships among serum T-cell subsets, CRP, levels and radiation pneumonitis (RP) in lung cancer patients receiving radiotherapy.

Methods

A case-control study with frequency matching was carried out. The case group comprised 36 lung cancer patients who had developed grade ≥2 RP after thoracic radiotherapy. The control group was 36 patients with lung cancer without RP. Patients in the case group received steroid therapy for 1 month after diagnosis of RP and were followed up for 3 months. T-cell subsets, CRP, and pulmonary function were detected at three time points (onset of RP and 1 and 3 months after diagnosis). Data for the control group were collected 3 months after radiotherapy. Treatment effectiveness was evaluated at 1 and 3 months after diagnosis of RP.

Results

Of the 36 patients in the case group, three with grade5 RP died from respiratory failure. The other 33 cases had all improved with steroid therapy at 3 months after RP diagnosis. In these 33, CD3⁺T-cell quantity, CD4⁺T-cell quantity, and of CD4⁺:CD8⁺ ratio in T-cell subsets decreased significantly and CRP increased (P<0.05) at the onset of RP compared with the control group. After steroid therapy, CD4⁺T-cell quantity increased significantly compared to before treatment. The same change was seen in CD4⁺:CD8⁺ ratio, whereas CRP levels decreased obviously, with treatment effectiveness improved. In addition, with the damage level of RP increased, CD4⁺ T -cell quantity decreased obviously and CRP levels increased accordingly at the onset of RP (P<0.05).

Conclusion

T-cell subsets and CRP may become effective immunological biomarkers for predicting damage from RP and evaluating treatment effectivesness of steroid therapy.

Primary impact of Gli1 on radioresistance in esophageal cancer

Radioresistance is the primary cause for the low efficacy of radiotherapy in the treatment of esophageal cancer (EC). Increasing evidence has demonstrated that the Sonic Hedgehog (Shh) signaling pathway may be involved in the pathology of various tumors, including EC. The present study aimed to examine the association between radioresistance in EC and the Sonic Hedgehog pathway, and to determine whether a downstream transcription factor of the Shh pathway, glioma-associated oncogene family zinc finger 1 (Gli1), serves a primary role in radioresistance. The radiation-resistant cell line Eca109R was established by repeated low dose (cumulative dose 60 Gy) irradiation of the human EC cell line Eca109. The level of cell radiosensitivity was determined by colony formation assay, and the localization of Gli1 was detected using immunofluorescence. Western blotting was used to determine the protein expression levels of Gli1, Shh, patched 1 (Ptch) and smoothened frizzled class receptor (Smo) in the two cell lines. Significantly higher levels of Gli1 were identified in the Eca109R cell line compared with those inEca109 cells (P<0.05). Additionally, western blotting analysis demonstrated an increased expression level of the Gli1, Shh, Ptch and Smo proteins in Eca109R, compared with Eca109 cells (P<0.05). Overexpression of Gli1 in the parental cell line led to decreased levels of radiosensitivity and radiosensitivity of the radioresistant cell line was restored through knockdown of Gli1. The present study demonstrated that Gli1 may be associated with the development of radioresistance in EC.

Fixed-jaw technique to improve IMRT plan quality for the treatment of cervical and upper thoracic esophageal cancer

The purpose of this study was to investigate the potential advantages of the fixed-jaw technique (FJT) over the conventional split-field technique (SFT) for cervical and upper thoracic esophageal cancer (EC) patients treated with intensity-modulated radiotherapy. The SFT and FJT plans were generated for 15 patients with cervical and upper thoracic EC. Dosimetric parameters and delivery efficiency were compared. An area ratio (AR) of the jaw opening to multileaf collimator (MLC) aperture weighted by the number of monitor units (MUs) was defined to evaluate the impact of the transmission through the MLC on the dose gradient outside the PTV50.4, and the correlation between the gradient index (GI) and AR was analyzed. The FJT plans achieved a better GI and AR (P < 0.001). There was a positive correlation between the GI and AR in the FJT (r = 0.883, P < 0.001) and SFT plans (r = 0.836, P < 0.001), respectively. Moreover, the mean dose (D_mean ), V_5Gy -V_40Gy for the lungs and the D_mean , V_5Gy -V_50Gy for the body-PTV50.4 in the FJT plans were lower than those in the SFT plans (P < 0.05). The FJT plans demonstrated a reduction trend in the doses to the spinal cord PRV and heart, but only the difference in the heart D_mean reached statistical significance (P < 0.05). The FJT plans reduced the number of MUs and subfields by 5.5% and 17.9% and slightly shortened the delivery time by 0.23 min (P < 0.05). The gamma-index passing rates were above 95% for both plans. The FJT combined with target splitting can provide superior organs at risk sparing and similar target coverage without compromising delivery efficiency and should be a preferred intensity-modulated radiotherapy planning method for cervical and upper thoracic EC patients.

Evofosfamide sensitizes esophageal carcinomas to radiation without increasing normal tissue toxicity

BACKGROUND AND PURPOSE

Esophageal cancer incidence is increasing and is rarely curable. Hypoxic tumor areas cause resistance to conventional therapies, making them susceptible for treatment with hypoxia-activated prodrugs (HAPs). We investigated in vivo whether the HAP evofosfamide (TH-302) could increase the therapeutic ratio by sensitizing esophageal carcinomas to radiotherapy without increasing normal tissue toxicity.

MATERIALS AND METHODS

To assess therapeutic efficacy, growth of xenografted esophageal squamous cell (OE21) or adeno (OE19) carcinomas was monitored after treatment with TH-302 (50 mg/kg, QD5) and irradiation (sham or 10 Gy). Short- and long-term toxicity was assessed in a gut mucosa and lung fibrosis irradiation model, sensitive to acute and late radiation injury respectively. Mice were injected with TH-302 (50 mg/kg, QD5) and the abdominal area (sham, 8 or 10 Gy) or the upper part of the right lung (sham, 20 Gy) was irradiated. Damage to normal tissues was assessed 84 hours later by histology and blood plasma citrulline levels (gut) and for up to 1 year by non-invasive micro CT imaging (lung).

RESULTS

The combination treatment of TH-302 with radiotherapy resulted in significant tumor growth delay in OE19 (P = 0.02) and OE21 (P = 0.03) carcinomas, compared to radiotherapy only. Irradiation resulted in a dose-dependent decrease of crypt survival (P < 0.001), mucosal surface area (P < 0.01) and citrulline levels (P < 0.001) in both tumor and non-tumor bearing animals. On the long-term, irradiation increased CT density in the lung, indicating fibrosis, over time. TH-302 did not influence the radiation-induced short-term and long-term toxicity, confirmed by histological evaluation.

CONCLUSION

The combination of TH-302 and radiotherapy might be a promising approach to improve the therapeutic index for esophageal cancer patients.

Factors relevant to the prognosis of patients with esophageal cancer who received intensity-modulated radiotherapy

BACKGROUND

The aim of this study was to evaluate the clinical factors relevant to the prognosis of patients with esophageal cancer who received intensity-modulated radiotherapy (IMRT).

METHODS

The data of 60 patients admitted to our hospital from January 2014 to December 2015 with pathologically confirmed esophageal cancer were retrospectively reviewed. All patients received IMRT. Patients were divided into groups according to two-year survival: those who survived > 2 years after treatment, and those who died within 2 years of treatment. The potential clinical factors relevant to prognosis were evaluated by logistic regression analysis.

RESULTS

Single factor analysis showed that lesion length (P < 0.05), tumor diameter (P < 0.05), T stage (P < 0.05), N stage (P < 0.05), and combined chemotherapy (P < 0.05) were associated with the prognosis of esophageal cancer patients who received IMRT. Logistic regression analysis demonstrated that T stage (odds ratio = 3.62; P < 0.05) and N stage (odds ratio = 2.98; P < 0.05) were independent factors relevant to prognosis.

CONCLUSION

T stage and N stage influence the long-term curative effects of IMRT for esophageal cancer. The higher the stage, the lower the two-year survival rate.

Comparison of intensity-modulated radiotherapy vs 3-dimensional conformal radiotherapy for patients with non-metastatic esophageal squamous cell carcinoma receiving definitive concurrent chemoradiotherapy: A population-based propensity-score-matched analysis

Whether the survival outcome of patients with non-metastatic esophageal squamous cell carcinoma (NM-ESCC) receiving definitive concurrent chemoradiotherapy (CCRT) is better with intensity-modulated radiotherapy (IMRT) or with 3-dimensional conformal radiotherapy (3DCRT) has been debated in the literature. We designed this population-based propensity-score (PS)-matched analysis to address this question. We identified eligible patients diagnosed between 2008 and 2015 from the Taiwan Cancer Registry and constructed a PS-matched cohort (1:1 for IMRT vs 3DCRT) to balance observable potential confounders. We compared the hazard ratio (HR) of death between IMRT and 3DCRT during the entire follow-up period. We also evaluated freedom from local regional recurrence (FFLRR) and esophageal cancer-specific survival (ECSS). Sensitivity analyses (SA) were performed to examine the robustness of our findings. Our study population constituted 558 patients who were well balanced with regard to the measured covariables. The HR of death with IMRT compared to 3DCRT was 0.43 (95% confidence interval 0.35-0.52, P < .001). The results remained significant for FFLRR and ECSS. In SA, our results remained significant when additional covariables were taken into consideration. The survival outcome of patients with NM-ESCC receiving CCRT might be better with IMRT vs 3DCRT. These study results should be interpreted with caution given some possible covariates lacking in the registry. Further studies are needed to clarify this issue.