(0629) Correlation of Worst Pattern of Invasion With Clinical and Prognostic Variables in Oral Cavity Cancer

Introduction: The worst pattern of invasion (WPOI) has been reported as an adverse prognostic factor of oral cavity squamous cell carcinoma (OCSCC), with the distinction of WPOI-5 (defined as a dispersion of ≥ 1 mm between tumor satellites), from patterns 1 to 4 is the most significant. Our goal was to explore the correlation of WPOI with clinical and prognostic variables.

Methods: This retrospective study included patients diagnosed with OCSCC and surgically treated at a tertiary care multidisciplinary head and neck cancer center between January 1, 2022, and August 31, 2023. Demographic and clinicopathologic characteristics were collected from electronic medical records. A comparison of group 1 consisting of patients with WPOI 1-4 with group 2 of WPOI-5 was performed. Correlations of the pathologic prognostic variables by group were performed. Statistical analysis included chi square and Fisher’s exact test for categorical variables and T-test for continuous variables.

Results: In total, 105 patients met the inclusion criteria; 60% were male with a mean age of 69 years. The WPOI 1-4 (group 1) included 91 patients (87%), whereas the WPOI-5 (group 2) included 14 (13%). There were no demographic differences between the study groups. There was a significant correlation of WPOI-5 with the extent of lymph nodal metastasis (LNM). Pathologic N0 was present in 57% vs 21% of patients in groups 1 and 2, respectively (p = 0.02). The mean number of LNM was 1.1 vs 3.9 in groups 1 and 2, respectively (p = 0.01). ENE was identified in only 5% of patients in the WPOI 1-4 group, compared to 57% of the WPOI-5 group (p = 0.0001). A significant association of WPOI-5 to advanced T stage, lymphovascular invasion, perineural invasion, and depth of invasion was identified.

Conclusions: WPOI-5 associates with clinical and histopathological features indicating a more aggressive local and regional disease than WPOI 1-4. The association with ENE raises the question of whether WPOI-5 is an independent risk factor for ENE, systemic metastasis and mortality.