Oral squamous cell carcinoma grading systems--analysis of the best survival predictor.

BACKGROUND

The TNM system has been used for decades in an attempt to predict clinical behavior and appropriate therapy for oral squamous cell carcinomas. Histopathologic classifications can be useful as an additional predictive tool. The purpose of this study was to apply four grading systems (Multiparameter Grading System, Malignancy Grading of the Deep Invasive Margins, World Health Organization grading system, and Histologic Risk Assessment) to oral squamous cell carncinomas and evaluate each system based on clinicopathologic parameters and patient survival.

METHODS

The files of 53 patients diagnosed with primary oral squamous cell carcinoma at the Brazilian National Cancer Institute were evaluated. All hematoxylin and eosin-stained slides were reviewed to confirm the original diagnosis and to determine histopathologic grading. Clinicopathologic information was obtained from medical records and tumor registries. Statistical analysis was performed using Fisher's exact test or the chi-square test, the Kaplan-Meier method, and the log-rank test.

RESULTS

The Multiparameter Grading System was statistically associated with pathologic staging (P = 0.02) and lymph node involvement (P = 0.0009). Differences in overall 5-year survival were significant for Histologic Risk Assessment (P = 0.015), pathologic staging (P = 0.001), lymph node status (P < 0.0001), and recurrence (P = 0.0001). Differences in cancer-specific 5-year survival were significant for Histologic Risk Assessment (P = 0.029), pathologic staging (P = 0.002), lymph node involvement (P < 0.0001), and recurrence (P < 0.0001). Poorly differentiated tumors were associated with the worst disease-free survival (P = 0.031) and recurrence (P = 0.043).

CONCLUSION

Of the grading systems evaluated, Histologic Risk Assessment demonstrated the best results for survival prediction in oral squamous cell carcinoma.