Grading systems and perineural invasion in oral squamous cell carcinoma - a disease-specific survival analysis

Abstract

Background: Oral squamous cell carcinoma (OSCC) is an aggressive cancer, with prognosis influenced by clinical variables as well grading systems and perineural invasion (PNI), which are associated to poorer outcomes, including higher rates of recurrence and metastasis. This study aims to evaluate OSCC using three grading systems and assess the impact of PNI and clinicopathologic parameters on patient survival.

Material and methods: Eighty-one primary OSCC samples were analyzed. Histopathological evaluations were performed utilizing Malignancy Grading of the Deep Invasive Margins, WHO grading system, and the Histologic Risk Assessment. S-100 immunohistochemistry was used to detect PNI. Five-year disease-specific survival (DSS) curves were generated using the Kaplan-Meier method, and the Cox proportional hazards model analyzed prognostic significance.

Results: Advanced clinical stage was significantly associated with reduced survival (p-value <0.001, HR = 4.07). Patients without regional lymph node involvement had better survival (p-value 0.002, HR = 0.37). Higher histologic risk assessment scores were linked to worse outcomes. Multifocal neural invasion significantly correlated with poorer survival compared to unifocal invasion (p-value 0.017, HR = 4.20). Patients undergoing surgery followed by adjuvant therapies had better survival rates.

Conclusions: Besides clinical stage and histological grade, PNI also showed to be a crucial prognostic factor in OSCC, necessitating aggressive treatment strategies.

Figure 1

A - WHO/Broders (2005) (Well-differentiaded x moderately/poorly differentiated); B - Malignancy grading of deep invasive margins (≤8 points x ≥9 points); C - Histologic risk assessment by Brandwein-Gensler et al. (2005) (≤2 points x ≥3 points); D - Neural Invasion - Foci (unifocal x multifocal).

Figure 2

A-F: Photomicrographs of perineural invasion (PNI) (arrows) in OSCC, affecting nerves of different sizes as well multifocal involvement. A and B - PNI in different regions of the same tumor (H&E, 10x). C- Presence of PNI in adjacent regions in the same tumor, involving minor nerve (H&E, 10x). D - Same region as in photomicrographs C, with S100 staining (10x). E and F: Another case of multifocal PNI, involving a major nerve (H&E and S100, 4x, respectively).