Aims: To test the validity of an invasive pattern grading score (IPGS) developed for oral squamous cell carcinoma (OSCC) as a prognostic indicator and to elucidate the relationship between the IPGS and clinical parameters.
Methods and results: The IPGS was applied to a total of 153 cases of OSCC. There were significant correlations between IPGS and distant metastasis (P = 0.01) or recurrence (P = 0.001). However, there were no significant correlations between IPGS and gender, age, size or extent, location, status of lymph node metastasis, clinical staging, or histological grading. Cases of OSCC with higher IPGS were associated with poor patient survival (P < 0.001) and higher probability of tumour recurrence (P = 0.001). Intraobserver (kappa = 0.74) and interobserver agreement (kappa = 0.67) were very satisfactory.
Conclusions: Our study confirms the validity of the IPGS, an indicator that is simple and easy to use. IPGS not only provides histological assessment of biological behaviour, but also offers an independent prognostic factor that may influence the treatment of OSCC.