局部晚期鼻咽癌诱导化疗后勾画靶区及OAR临床应用初探

Study on Delineation Gross Tumor Volume and Organs at Risk on the Dose Distribution and Clinical Treatment After Induction Chemotherapy for Locally Advanced Nasopharyngeal Carcinoma

[目的]探讨局部晚期鼻咽癌诱导化疗后肿瘤体积缩小,按化疗后肿瘤改变勾画大体肿瘤体积（GTV）对靶区体积和正常组织（OAR）剂量、近期疗效的影响及临床应用价值。[方法]46例局部晚期鼻咽癌,采用TP方案诱导化疗2个周期,按化疗后勾画GTV及OAR,逆向5野适形调强（IMRT）设野,对两次放疗计划靶体积差值及剂量学差异行配对t检验;同期DDP化疗,观察近期疗效及治疗失败情况。[结果]诱导化疗前和后原发灶GTV平均体积分别为（53.86±26.54）cm^3和（35.01±20.47）cm^3（t=4.09,P=0.001）;颈淋巴结GTVnd分别为（37.42±16.39）cm^3和（22.82±11.05）cm^3（t=4.82,P=0.001）;诱导化疗使肿瘤总体积减少了35%、39%;诱导化疗后脑干、脊髓、颞叶、眼球、腮腺所受最大剂量区体积、平均剂量减少5%-17%;3年LCR、DMFS、DFS、OS分别为89.1%、82.6%、73.9%、87.0%。GTV边缘复发率为10.9%,远处转移率为17.4%。[结论 ]局部晚期鼻咽癌TP方案诱导化疗后肿瘤体积明显缩小,按化疗后肿瘤勾画GTV的调强放疗能使高剂量区体积减少,OAR最大剂量区体积减小,OAR可得到较好保护;肿瘤局部控制率、近期疗效较好;远处转移、GTV边缘复发是治疗失败主要原因,值得临床继续深入研究。

[Objective] To investigate the impact and clincal value of GTV and OAR delineation on the dose and clinical treatment outcome after induction chemotherapy for locally advanced nasopharyngeal carcinoma.[Methods] Forty-six patients with LANC were enrolled and treated with 2circles of TP regimen followed by five fields intensity-modulated radiotherapy（IMRT）with concurrent DDP chemotherapy. Target volumes were delineated based on fused CT imaging before and after induction chemotherapy following project determination. Tumor target volumes after and before induction chemotherapy were respectively delineated according to imaging tumor residues and were overlaid by GTV and OAR. The differences of tumor target volumes of induction chemotherapy before and after were measured and analyzed by paired t-test.The clinical treatment outcome and treatment failure of all patients were observed. [Results] Before and after induction chemotherapy,the average volumes of GTVnxwere（53. 86±26.54）cm^3 and（35.01±20.47）cm^3（t=4.09,P=0.001） respectively,the average volumes of GTVndwere（37.42±16.39）cm^3and（22.82±11.05）cm^3（t =4.82,P =0.001） respectively.The average total volumes of gross tumor was reduced of 35% 、39%,and the volumes of maximum dose and mean dose area in brainstem,spinal cord,temporal lobe,eyeball as well as parotid decreased 5%-17%. With a sample size of 46 patients,the 3-year local control（LCR）,distant metastasis-free survival（DMFS）,disease-free survival（DFS） and over all survival（OS）,were 89.1%,82.6%,73.9% and 87.0%. While GTV field margin recurrence rate was10.9%,distant metastasis rate was 17.4%. [Conclusions] LANC treated by 2 cycles TP regimen followed by IMRT with concurrent cisplatin chemotherapy shows significant shrinkage of tumor volume. The volume of high dose region which caused by normally recovered tissues are decreased by redelineation of target volume in OAR after induction chemotherapy,which have excellent local control rate and short-term treatment outcome.Distant metastasis and GTV field margin recurrence are the most common failure pattern after treatment. The role of long-term treatmentoutcome and clincal value in the treatment of locally advanced NPC needs further study.