Radiotherapy with neoadjuvant chemotherapy versus concurrent chemoradiotherapy for ascending-type nasopharyngeal carcinoma:a retrospective comparison of toxicity and prognosis

Background:In the era of intensity?modulated radiotherapy(IMRT),the role of neoadjuvant chemotherapy(NACT)in treating ascending?type nasopharyngeal carcinoma(NPC)is under?evaluated.This study was to compare the efficacy of NACT followed by IMRT(NACT+RT)with the efficacy of concurrent chemoradiotherapy(CCRT)on ascending?type NPC.Methods:Clinical data of 214 patients with ascending?type NPC treated with NACT+RT or CCRT between Decem?ber 2009 and July 2011 were analyzed.Of the 214 patients,98 were treated with NACT followed by IMRT,and 116 were treated with CCRT.The survival rates were assessed using Kaplan–Meier analysis,and the survival curves were compared using a log?rank test.Results:The 4?year overall survival,locoregional failure?free survival,distant failure?free survival,and failure?free sur?vival rates were not significantly different between the two groups(all P>0.05).However,patients in the CCRT group exhibited more severe acute adverse events than did patients in the NACT+RT group during radiotherapy,includ?ing leukopenia(30.2%vs.15.3%,P=0.016),neutropenia(25.9%vs.11.2%,P=0.011),and mucositis(57.8%vs.40.8%,P=0.028).After radiotherapy,patients in the CCRT group exhibited significantly higher rates of xerostomia(21.6%vs.Conclusions:The treatment outcomes of the NACT+RT and CCRT groups were similar;however,CCRT led to higher rates of acute and late toxicities.NACT+RT may therefore be a better treatment strategy for ascending?type NPC.

Long-term outcome and late toxicities of simultaneous integrated boost-intensity modulated radiotherapy in pediatric and adolescent nasopharyngeal carcinoma

The application of simultaneous integrated boost-intensity modulated radiotherapy(SIB-IMRT)in pediatric and adolescent nasopharyngeal carcinoma(NPC)is underevaluated.This study aimed to evaluate long-term outcome and late toxicities in pediatric and adolescent NPC after SIB-IMRT combined with chemotherapy.Thirty-four patients(aged 8–20 years)with histologically proven,non-disseminated NPC treated with SIB-IMRT were enrolled in this retrospective study.The disease stage distribution was as follows:stage I,1(2.9%);stage III,14(41.2%);and stage IV,19(55.9%).All patients underwent SIBIMRT and 30 patients also underwent cisplatin-based chemotherapy.The prescribed dose of IMRT was64–68 Gy in 29–31 fractions to the nasopharyngeal gross target volume.Within the median follow-up of 52months(range,9–111 months),1 patient(2.9%)experienced local recurrence and 4(11.8%)developed distant metastasis(to the lung in 3 cases and to multiple organs in 1 case).Four patients(11.8%)died due to recurrence or metastasis.The 5-year locoregional relapse–free survival,distant metastasis–free survival,disease-free survival,and overall survival rates were 97.1%,88.2%,85.3%,and 88.2%,respectively.The most common acute toxicities were grades 3–4 hematologic toxicities and stomatitis.Of the 24 patients who survived for more than 2 years,16(66.7%)and 15(62.5%)developed grades 1–2 xerostomia and ototoxicity,respectively.Two patients(8.3%)developed grade 3 ototoxicity;no grade 4 toxicities were observed.SIB-IMRT combined with chemotherapy achieves excellent long-term locoregional control in pediatric and adolescent NPC,with mild incidence of late toxicities.Distant metastasis is the predominant mode of failure.

Prognostic scoring system for locoregional control among the patients with nasopharyngeal carcinoma treated by intensity-modulated radiotherapy

The prognostic value of T category for locoregional control in patients with nasopharyngeal carcinoma(NPC)has decreased with the extensive use of intensity-modulated radiotherapy(IMRT).We aimed to develop a prognostic scoring system(PSS)that incorporated tumor extension and clinical characteristics for locoregional control in NPC patients treated with IMRT.The magnetic resonance imaging scans and medical records of 717 patients with nonmetastatic NPC treated with IMRT at Sun Yat-sen University Cancer Center between January 2003 and January 2008 were reviewed.Age,pathologic classification,primary tumor extension,primary gross tumor volume(GTV-p),T and N categories,and baseline lactate dehydrogenase(LDH)level were analyzed.Hierarchical cluster analysis as well as univariate and multivariate analyses were used to develop the PSS.Independent prognostic factors for locoregional relapse included N2–3 stage,GTV-p≥26.8 mL,and involvement of one or more structures within cluster3.We calculated a risk score derived from the regression coefficient of each factor and classified patients into four groups:low risk(score 0),intermediate risk(score>0 and≤1),high risk(score>1 and≤2),and extremely high risk(score>2).The 5-year locoregional control rates for these groups were 97.4%,93.6%,85.2%,and 78.6%,respectively(P<0.001).We have developed a PSS that can help identify NPC patients who are at high risk for locoregional relapse and can guide individualized treatments for NPC patients.

Numerical simulation and optimization design of the EGR cooler in vehicle

The EGR (exhaust gas recirculation) technique can greatly reduce the NOx emission of diesel engines, especially when an EGR cooler is employed. Numerical simulations are applied to study the flow field and temperature distributions inside the EGR cooler. Three different models of EGR cooler are investigated, among which model A is a traditional one, and models B and C are improved by adding a helical baffle in the cooling area. In models B and C the entry directions of cooling water are different, which mostly influences the flow resistance. The results show that the improved structures not only lengthen the flow path of the cooling water, but also enhance the heat exchange rate between the cool and hot media. In conclusion we suggest that the improved structures are more powerful than the traditional one.

新辅助化疗联合放疗与同期放化疗对上行型鼻咽癌疗效的比较:毒性和预后的回顾性分析

背景与目的在调强放射治疗(intensity?modulated radiotherapy, IMRT)的时代,新辅助化疗(neoadjuvant chemotherapy, NACT)在治疗上行型鼻咽癌(nasopharyngeal carcinoma, NPC)中的作用被低估了。本研究旨在比较NACT结合IMRT(NACT+RT)与同期放化疗(concurrent chemoradiotherapy,CCRT)对治疗上行型鼻咽癌的疗效。方法分析2009年12月至2011年7月期间用NACT+RT或CCRT治疗的214例上行型鼻咽癌患者的临床数据。在214例患者中,98例接受了NACT+RT治疗,116例接受了CCRT治疗。用Kaplan?Meier法分析存活率,并用log?rank检验比较存活曲线。结果两组患者在4年总生存率、局部区域无复发生存率、无远处转移生存率和无进展生存率均没有显著差异(均P> 0.05)。然而,CCRT组患者在放疗期间比NACT+RT组患者表现出更严重的急性不良反应,包括白细胞减少(30.2%vs. 15.3%, P=0.016)、中性粒细胞减少(25.9%vs.11.2%, P=0.011)和黏膜炎(57.8%vs.40.8%, P=0.028)。放疗结束后,CCRT组患者表现出较高比例的口腔干燥症(21.6%vs. 10.2%, P=0.041)和听力损失(17.2%vs. 6.1%,P=0.023)。结论 NACT+RT和CCRT两组的治疗结果相似。然而,CCRT组会导致更高比例的急性和迟发性毒性。因此,NACT+RT可能是治疗上行型鼻咽癌更好的方法。

Simulation and experimental study of electro-pneumatic valve used in air-powered engine

To evaluate the performance of newly designed electro-pneumatic valves (EPVs) for the air-powered engine (APE) and study laws of parameters affecting them, a simulation model was established based on the thermodynamics and mechanics theories. Experiments were set up to determine the instantaneous effective orifice area of solenoid valve by the constant volume discharge method. The simulation model was also validated by comparing the measured displacement curve with the simulated displacement curve of the valve in the pressure of 0.16 and 0.49 MPa. Simulation and experimental results showed that maximum working frequency of the designed EPV could reach 30 Hz corresponding to 2000 r/min of engine rotating speed. Based on simulation results, impacts of temperature and pressure of control air on delay time, full opening/closing time and seating velocity of EPV were analyzed. The simulation model could also act as EPV simulation prototype in designing the air exchange control system of APE.

Simulation, experimentation, and collaborative analysis of adjacent heat exchange modules in a vehicular cooling system

A cooling system consisting of several heat exchange modules is a necessary part of an automobile, and its performance has a direct effect on a vehicle's energy consumption. Heat exchangers, such as a charged air cooler (CAC), radiator, oil cooler, or condenser have different structures and can be arranged in various orders, and each combination may produce different effects because of interactions among them. In this study, we aimed to explore the principles governing interactions among adjacent heat exchangers in a cooling system, using numerical simulation and experimental technology. 3D models with different combinations were developed, compared, and analyzed comprehensively. A wind tunnel test platform was constructed to validate the computational results. We found that the heat dissipation of the modules was affected slightly by their relative position (the rules basically comply with the field synergy principle), but was independent of the modules' spacing within a certain distance range. The heat dissipation of one module could be effectively improved by restructuring, but with a penalty of higher resistance. However, the negative effect on the downstream module was much less than expected. The results indicated that the intensity of heat transfer depends not only on the average temperature difference between cold and hot mediums, but also on the temperature distribution.