[The role of retropharyngeal lymph node metastasis in staging of nasopharyngeal carcinoma].
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 Radiation 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 N0 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.
State Key Laboratory of Oncology in South China, Guangzhou, Guangdong 510060, P. R. China.
Ling-Long
LL
Tang
Li-Zhi
LZ
Liu
Jun
J
Ma
Jing-Feng
JF
Zong
Ying
Y
Huang
Ai-Hua
AH
Lin
Tai-Xiang
TX
Lu
Nian-Ji
NJ
Cui
D000293:Adolescent; D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology* / Q000532:radiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000532:radiotherapy; D009367:Neoplasm Staging; D010614:Pharynx; D011379:Prognosis; D015996:Survival Rate; D014057:Tomography, X-Ray Computed