Comparison of Volumetric and Dosimetric Variations in Nasopharyngeal Carcinoma during Intensity-modulated Radiation Therapy with and without Neoadjuvant Chemotherapy

Objective Patients with nasopharyngeal carcinoma(NPC)undergoing intensity-modulated radiation therapy(IMRT)may experience significant volumetric and dosimetric variations throughout the treatment course.However,neoadjuvant chemotherapy may reduce the extent of these variations.This study was carried out to evaluate volumetric and dosimetric changes in target volumes and organs at risk(OARs)during IMRT in patients with locally advanced NPC who received concurrent chemoradiotherapy(CCRT)alone or in combination with neoadjuvant chemotherapy(NACT).Methods 35 NPC patients were recruited for this study and divided into the NACT(n=15)and CCRT(n=20)groups.Computed tomography(CT)scans were performed before neoadjuvant chemotherapy,before IMRT,before the 24 th fraction of IMRT,and after treatment.The original plan(plan 0)was based on CT images collected before IMRT.Hybrid plan 1(plan 1)and hybrid plan 2(plan 2)were generated by applying the beam configurations of plan0 to the CT scans collected before the 24 th fraction of IMRT and after treatment.Volumetric and dosimetric variations were assessed by comparing the results of plan 0 with those of plan 1 and plan 2.Results In the NACT group,compared with that in plan 0,the primary gross tumor volume(GTVnx)decreased by 33.2%±18.4%and 50.5%±12.6%in plan1 and plan 2,respectively.In the CCRT group,the corresponding reduction rates in plan 1 and plan 2 were 49.4%±8.0%and 77.8%±28.1%,respectively.The volume decrease rates in the NACT group were less than those in the CCRT group(P<0.001).In the NACT group,compared with that of plan0,the dose to 95%of the volume(D95)for the planning target volume of the primary tumor(PTVnx)decreased by 1.0%±0.7%and 0.6%±0.6%in plan 1 and plan 2,respectively.In the CCRT group,the corresponding decrease rates in plan 1 and plan 2 were 4.2%±3.8%and 6.1%±6.3%,respectively.The decrease rate of D95 for PTVnx in the NACT group was less than that in the CCRT group(P<0.001).Similar results among the plans were found in terms of D99,Dmean,V93 for PTVnxand PTVnd,and Dmeanfor the parotid glands.Conclusion Neoadjuvant chemotherapy reduces the extent of volumetric and dosimetric variations in target volumes and OARs during IMRT and,thus,helps achieve better target volume coverage,protects adjacent important structures,and minimizes unnecessary replanning during radiotherapy.

Intensity modulated radiation therapy in elderly patients with nasopharyngeal carcinoma

Purpose To evaluate the outcomes in elderly patients with nasopharyngeal carcinoma(NPC)treated by intensity modulated radiation therapy(IMRT).Methods Patients with NPC aged≥70 years old who received intensity-modulated radiation therapy≥60 Gy were recruited into this study.The overall survival(OS),progression-free survival(PFS),cancer-specific survival(CSS),locoregional recurrence-free rate(LRFR)and distant metastasis-free rate(DMFR)were calculated using the Kaplan–Meier method.The Cox proportional hazards model was applied to perform multivariate analysis for independent prognosticators using meaningful variables from the univariate analysis.Results One hundred ninety seven patients with NPC≥70 years were recruited from the 4351 newly diagnosed NPC patients from January 2011 to December 2020.The 5-year OS,CSS,PFS,LRFR and DMFR were 59.6%,78.9%,51.3%,91.6%and 78.9%,respectively.the plasma EBV DNA was the only prognostic factor for OS,the overall staging was the only prognostic factor for CSS,and plasma EBV DNA and N category were borderline significant factor for DMFR.We did not find any prognosticator for PFS and LRFR.Conclusions The survival after IMRT for elderly patients with NPC is suboptimal.Further study stratified by comorbidity and geriatric assessment is needed.

鼻咽癌调强放疗同步节拍化疗的临床研究

目的观察鼻咽癌调强放疗(intensity modulated radiation therapy,IMRT)同步口服卡培他滨节拍化疗的疗效及毒副反应。方法 118例鼻咽癌患者,随机分为实验组和对照组,对照组给予6MXV-X线根治性调强适形放疗,实验组在进行调强放射治疗的同时,节拍性口服卡培他滨每次500mg,每日2次,疗程12个月或至疾病进展为止。观察临床疗效和毒副反应。结果共有111例患者完成实验,近期疗效:实验组有效率(RR)100%,对照组有效率98.3%,两组间差异无统计学意义(P>0.05)。远期疗效:实验组1、3、5年生存率分别为96.5%、92.3%和78.3%,中位总生存时间(OS)为58.838个月,中位无进展生存时间(PFS)为40.719个月;对照组1、3、5年生存率分别为89.7%、77.8%和50.0%,中位OS为50.126个月,中位PFS为24.962个月。两组间总生存时间和无进展生存时间均有统计学差异(OS:χ2=5.587,P=0.018;PFS:χ2=3.868,P=0.049)。两组治疗结束后均出现VEGF、PDGF-BB水平下降,TSP-1水平升高,且实验组变化的幅度较对照组更为显著,两组间各指标变化水平均有统计学差异(P<0.05)。两组不良反应主要表现为白细胞减少、皮肤反应及口腔、口咽部黏膜反应,两组间不良反应无统计学差异(P>0.05)。结论鼻咽癌调强放疗同步口服卡培他滨节拍化疗能提高患者的远期生存率,增强抗肿瘤新生血管形成能力,而并未增加毒副反应发生率及严重程度。