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[Analysis of risk factors in the prediction of distant metastases of head and neck squamous cell carcinomas].

OBJECTIVE
To investigate the risk factors related with distant metastases (DM) from head and neck squamous cell carcinomas (HNSCC).


METHODS
A retrospective study was carried out to review the histopathological data from 532 HNSCC patients treated in Bethune International Peace Hospital from February 1978 to February 1998. The incidence and the risk factor for DM were evaluated in a model that included the following factors: sex, age, clinical staging, T and N staging, site of primary tumor, depth of primary tumor infiltration, histological grade of primary tumor, presence of cervical lymph node metastasis, number of positive neck nodes and levels involved, and presence of extracapsular nodal spread. Univariate chi2 test and multivariate stepwise logistic regression model were used for the analysis. Statistical analysis of overall survival was performed using Kaplan-Meier method.


RESULTS
Sixty cases (11.3%) presented distant metastases in 532 patients of head and neck squamous cell carcinomas. In a univariate analysis, it was confirmed that the following variables correlated to DM, i.e., clinical staging (P = 0.0126), T classification (P = 0.0082), site of primary tumor (P = 0.0011), depth of primary tumor infiltration (P = 0.0005) , presence of cervical metastasis (P = 0.0057), number of positive neck nodes (P = 0.0149) and levels involved (P = 0.0034), presence of extracapsular nodal spread (P = 0.0118). In a multivariate analysis, the most significant risk factors for DM were the site of primary tumor and the depth of primary tumor infiltration. Kaplan-Meier analysis showed that overall survival rates of 60 HNSCC patients who presented distant metastases were 51.7% at 1 year, 13.3% at 3 years, 6.5% at 5 years, respectively.


CONCLUSION
The site of primary tumor and the depth of primary tumor infiltration are the key risk factors in determining the development of DM in HNSCC patients. Patients with laryngeal and hypopharyngeal carcinomas and patients with primary tumor infiltrating muscular, bone or cartilage level have the highest risk of developing DM.