鼻咽癌Ib区是否常规预防照射的临床分析

Prophylactic irradiation at the level Ib for nasopharyngeal carcinoma: should that be a routine?

目的通过分析鼻咽癌Ib区转移的发生率及其转移规律,探讨Ib区是否需要常规进行预防照射,为准确进行颈部放疗靶区的个体化设计、减少颌下腺照射提供证据。方法收集2001年1月～2005年6月病理确诊的初治鼻咽癌患者疗前增强CT/MRI影像学资料,颈部转移淋巴结分区方法采用SOM分区法。结果共338例可评价,颈部淋巴结转移率75.1%。颈部Ⅰb、Ⅱa、Ⅱb、Ⅲ、Ⅳ、Ⅴa、Ⅴb及锁上区淋巴结转移率分别为0.9%、49.1%、60.7%、26.0%、5.9%、9.5%、3.8%和0.9%,跳跃性转移率为2.4%;按转移风险(以>5%为高危区域)分析其转移的规律为:(1)当发生Ⅱ区淋巴结转移时,高危区域为同侧Ⅲ、Ⅳ、Ⅴa、Ⅴb区;(2)Ⅲ区淋巴结转移时,高危区域为同侧Ⅱ、Ⅳ、Ⅴa、Ⅴb区;(3)Ⅳ区淋巴结转移时,高危区域为同侧Ⅱ、Ⅲ、Ⅴa、Ⅴb、锁上区;(4)Ⅴa区淋巴结转移时,高危区域为同侧Ⅱ、Ⅲ、Ⅳ、Ⅴb、锁上区;(5)Ⅴb区发生淋巴结转移时,高危区域为同侧Ⅱ、Ⅲ、Ⅳ、Ⅴa、锁上区;(6)一侧颈发生淋巴结转移时,高危区域为对侧Ⅱ、Ⅲ、Ⅴa区。结论Ⅰb区淋巴结转移的发生率极低;当颈部任何区域发生淋巴结转移时,Ⅰb区均非高危区域。Ⅰb区不常规预防照射符合鼻咽癌淋巴结转移规律。

Objective To assess the necessity of routine prophylactic irradiation at the level Ib for nasopharyngeal carcinoma（NPC）.Methods Newly diagnosed NPC patients between January,2001 and June,2005 were enrolled in this study.The nodal distribution in each region was calculated from the data of transversal contrast enhance CT or magnetic resonance scan of the head and neck.Results Cervical node involvement was found in 75.1% of the 338 patients enrolled.The rates of involvement at levels Ib,IIa,IIb,III,IV,Va,Vb and in the supra-clavicular region were 0.9%,49.1%,60.7%,26.0%,5.9%,9.5%,3.8% and 0.9%,respectively.Skip metastasis occurred only in 2.4% of the cases.The high risk region（defined by a probable risk5%） of nodal metastases was（1） the ipsilateral levels III,IV,Va,and Vb in case of level II involvement,（2） the ipsilateral levels II,IV,Va,and Vb in case of level III involvement,（3） the ipsilateral levels II,III,Va,Vb and the supra-clavicular region in case of level IV involvement,（4） the ipsilateral levels II,III,IV,Vb and the supra-clavicular region in case of level Va involvement,（5） the ipsilateral levels II,III,IV,Vb,and the supra-clavicular region in case of level Vb involvement,（6） the contralateral levels II,III,and Va in case of unilateral cervical node involvement.Conclusions Nodal involvement in NPC patients rarely occurs at the level Ib,which is not a high risk region whatever the regions may be to have lymph node metastasis and therefore does not need routine prophylactic irradiation.