咽后淋巴结转移在鼻咽癌分期中的意义

The Role of Retropharyngeal Lymph Node Metastasis in Staging of Nasopharyngeal Carcinoma

背景与目的:鼻咽癌咽后淋巴结转移的发生率高,X92分期系统未明确其在临床分期中的意义,本研究旨在分析咽后淋巴结转移对鼻咽癌预后的影响及评价它在鼻咽癌分期中的意义。方法:收集1999年1月至1999年12月间中山大学肿瘤防治中心放疗科收治的经病理证实、治疗前进行鼻咽和颈部增强CT扫描的初诊鼻咽癌749例。多因素分析采用Cox风险比例模型,根据临床分期的原则,采用风险一致性、风险差异性、预后预测及分布均衡性等指标进行评价。结果:咽后淋巴结转移的发生率为51.5%。T分期、N分期及临床分期晚的患者咽后淋巴结转移发生率分别为57.8%、60.3%和57.9%,高于早期患者的发生率(45.2%、47.6%和38.9%),其差异均有统计学意义(P值分别为0.001、0.001、<0.001)。咽后淋巴结转移患者和无咽后淋巴结转移患者5年总生存率分别为58.7%和72.2%,5年无远处转移生存率分别为74.5%和84.9%,其差异有统计学意义(P均<0.001);多因素分析,咽后淋巴结转移并不是影响鼻咽癌总生存率的独立预后因素,对无远处转移生存率的影响有临界意义(P=0.053)。N0合并咽后淋巴结转移的死亡及远处转移的风险比分别为0.540及0.411,与N1组(0.601及0.555)相似。将其归为N1或T2比较,前者N分期预后的风险一致性较好,但N分期分布极不均衡,N1患者比例达50.2%。后者N分期及临床分期预后的风险差异性明显,且T、N分期及临床分期分布均衡性较好。结论:咽后淋巴结转移对鼻咽癌无远处转移生存率可能有影响,在目前&92分期系统及现行的鼻咽癌原发灶放射治疗模式的情况下,将咽后淋巴结转移归为T2分期内容更符合分期的原则。

BACKGROUND ＆ OBJECTIVE. The prevalence of retropharyngeal lymph node （RLN） metastasis in nasopharyngeal carcinoma （NPC） is high, but its role in ＇92 Fuzhou staging system for NPC is uncertain. This study was to identify the prognostic value of RLN metastasis in NPC, and to evaluate its role in the staging system. METHODS： Clinical data of 749 untreated patients with histologically diagnosed NPC, without metastasis, presented between Jan. 1999 and Dec. 1999 at the Department of Radioation Oncology of Cancer Center of Sun Yat-sen University, were reviewed. All patients received enhanced spiral CT scan on the nasopharynx and whole neck before treatment. Cox regression model was used to investigate the prognostic value of RLN metastasis. According to the principle of the staging system, the indices of hazard consistency, hazard discrimination, and distribution were evaluated to identify the role of RLN metastasis in the staging system for NPC. RESULTS： The occurrence rate of RLN metastasis was 51.5%; the occurrence rates were significantly higher in the patients in advanced T stage, N stage, and clinical stage than in the patients in early stages （57.8% vs. 45.2%, P=0.001 ; 60.3% vs. 47.6%, P=0.001; 57.9% vs. 38.9%, P〈0.001）. The 5-year overall survival rate and 5-year distant metastasis-freely survival rate were significantly lower in the patients with RLN metastasis than in the patients without RLN metastasis （58.7% vs. 72.2%, P〈 0.001; 74.5% vs. 84.9%, P〈0.001）. In multivariate analysis, RLN metastasis was not a prognostic factor for overall survival, but borderline significant difference was observed for distant metastasis-freely survival （P=0.053）. The hazard ratios of death and distant metastasis for NO stage with RLN metastasis were 0.540 and 0.411, respectively, which was similar to those for N1 stage （0.601 and 0.555, respectively）. Classifying RLN metastasis to N1 stage improved the hazard consistency in the N classification, but the distribution was unsatisfactory, and the proportion of N1 stage patients was 50.2%. Classifying RLN metastasis to T2 stage improved the hazard discrimination, with good balances of distribution found in T classification, N classification, and clinical staging. CONCLUSIONS： Based on the enhanced CT image, RLN metastasis tends to affect distant metastasis-freely survival of NPC patients. According to the principle of ＇92 Fuzhou staging system and present patterns of radiotherapy for the primary tumor, classifying RLN metastasis to T2 stage is more reasonable.