MULTIVARIATE-ANALYSIS OF OCCULT LYMPH-NODE METASTASIS AS A PROGNOSTICINDICATOR FOR PATIENTS WITH SQUAMOUS-CELL CARCINOMA OF THE ORAL CAVITY

BACKGROUND. The biologic aggressiveness of squamous cell carcinoma of the oral cavity is reflected in its ability to metastasize to regional cervical lymph nodes. Patients with clinically negative cervical lymp h nodes are believed to have a good prognosis; however, the prognosis of patients with lymph node metastasis occurring after excision or rad iotherapy of the primary tumor is poor. METHODS. Univariate and multiv ariate analyses for occult lymph node metastasis (ONM) in 172 patients with clinically negative cervical lymph nodes were performed by the a uthors to elucidate the clinical and histologic tumor risk factors to enhance their ability to predict ONM. A multivariate Cox proportional hazards model and Hayashi's quantification theory type II were used to analyze prognostic factors and to determine the probability of ONM. R ESULTS. Using Cox's proportional regression model, the factors linked to cancer specific survival were selected: tumor differentiation (P = 0.0330), mode of carcinoma invasion (P = 0.0175), and ONM (P = 0.0433) . Pathologically identified metastatic lymph nodes were found in 21.5 % of the cases studied (37 of 172 cases). The 5-year cancer specific s urvival was 94.0 % for patients without lymph node metastasis, and 51. 0 % for patients with ONM (P < 0.0001, log rank test). The most signif icant predictors for ONM of each of the clinical and histologic factor s, in descending order, were: mode of carcinoma invasion, intensity of lymphocytic infiltration, degree of differentiation, number of mitoti c figures, and type of growth by means of Hayashi's quantification the ory type II. The presence or absence of ONM in 147 of 172 patients (85 .5%) was correctly predicted by the score at the point of intersection of the two curves, which was -0.03. Further investigation revealed th at 28 of 32 new cases were differentiated accurately by means of this diagnostic system. CONCLUSIONS. The results of the current study sugge st that this method of analysis can establish a reliable predictor of ONM, thereby facilitating correct choices for surgical procedures to e nhance the survival rates of patients with clinically negative cervica l lymph nodes. (C) 1997 American Cancer Society.