Development of a New Outcome Prediction Model in Early-stage Squamous Cell Carcinoma of the Oral Cavity Based on Histopathologic Parameters With Multivariate Analysis

The aim of this study was to evaluate the histopathologic parameters that predict lymph node metastasis in patients with oral squamous cell carcinoma (OSCC) and to design a new assessment score on the basis of these parameters that could ultimately allow for changes in treatment decisions or aid clinicians in deciding whether there is a need for close follow-up or to perform early lymph node dissection. Histopathologic parameters of 336 cases of OSCC with stage cT1/T2 N0M0 disease were analyzed. The location of the tumor and the type of surgery used for the management of the tumor were recorded for all patients. The parameters, including T stage, grading of tumor, tumor budding, tumor thickness, depth of invasion, shape of tumor nest, lymphoid response at tumor-host interface and pattern of invasion, eosinophilic reaction, foreign-body giant cell reaction, lymphovascular invasion, and perineural invasion, were examined. Ninety-two patients had metastasis in lymph nodes. On univariate and multivariate analysis, independent variables for predicting lymph node metastasis in descending order were depth of invasion (P=0.003), pattern of invasion (P=0.007), perineural invasion (P=0.014), grade (P=0.028), lymphovascular invasion (P=0.038), lymphoid response (P=0.037), and tumor budding (P=0.039). We designed a scoring system on the basis of these statistical results and tested it. Cases with scores ranging from 7 to 11, 12 to 16, and ≥17 points showed LN metastasis in 6.4%, 22.8%, and 77.1% of cases, respectively. The difference between these 3 groups in relation to nodal metastasis was very significant (P<0.0001). A patient at low risk for lymph node metastasis (score, 7 to 11) had a 5-year survival of 93%, moderate-risk patients (score, 12 to 16) had a 5-year survival of 67%, and high-risk patients (score, 17 to 21) had a 5-year survival of 39%. The risk of lymph node metastasis in OSCC is influenced by many histologic parameters that are not routinely analyzed in pathologic reports. These significant independent factors were graded to design a scoring system that permits accurate evaluation of the risk of metastasis with accuracy independent of the traditional TNM system or isolated histologic parameters. The need for neck node dissection can be predicted depending upon the scores obtained.