Comparison of the histologic risk assessment model between lower lip and oral squamous cell carcinoma

The histologic risk assessment (HRA) grading system was proposed as a practical measure to predict clinical outcome and its effectiveness has been shown in several studies. It has been suggested that the HRA model might exhibit differences among various oral subsites. The aim of the present study was to compare this system between squamous cell carcinomas (SCCs) of the lower lip (LL) and oral cavity.

All primary SCCs located in the LL and oral cavity were retrieved and graded using the HRA model. Data regarding risk score (RS), perineural invasion (PNI), lymphocytic infiltration (LI) and worst pattern of invasion (WPOI) were compared between LL and oral SCCs using χ² analysis (P<0.05).

There were a total of 33 LLSCCs, of which 15, 8 and 10 were categorized as low-risk (RS=0), intermediate-risk (RS=1-2) and high-risk (RS≥3) tumors, respectively. Corresponding values in the 48 oral SCCs were 7, 15 and 26 cases. Significant differences in RS (P=0.00), LI (P=0.01) and WPOI (P=0.01) were observed between LL and oral tumors.

The HRA model could be included among the various factors suggested to be different between lip and oral SCCs. Low-risk tumors were more prevalent in the lip which corroborates the less aggressive nature of these cancers. Considering the significantly higher LI in LL SCCs, inflammation may be regarded as an important factor in regulating the invasive behavior of these tumors.