Outcomes for patients with early stage well (WD) or moderately (MD) differentiated oral cavity SCC (OCSCC) can vary. Research is emerging on the impact of Worst Pattern of Invasion (WPI) on oral cavity SCC (OCSCC) prognosis. WPI is a 5-category system which accounts for the nature and density of invasive cell clusters within tumours, rather than the degree of differentiation of overall tumour. WPI may more-accurately prognosticate poor patient outcomes. Aim To examine early-stage OCSCC specimens to determine if WPI more accurately indicates poor patient outcomes than differentiation. This aims to contribute to emerging evidence for WPI in OC SCC grading and is the largest Australian study to date of WPI for OCSCC. Method Patient lists from Princess Alexandra Hospital HN MDT from 01/01/2018-01/05/2022 were examined. Eligible patient data was extracted from EMR. Specimens were re-examined by a senior pathologist (CC) for WPI reporting. Rate of patient outcomes were calculated in WD-, MD-, and PD- groups and compared with WPI I-IV and WPI V. Pearson correlation curves were generated. Inclusion •>18yo •T1-T2N0M0 OCSCC •Treated with curative intent surgery, +/- adjuvant therapies •Must have at least 2 years follow-up or death Exclusion •Treatment of recurrence Ethics Approval: Metro South HREC/2023/QMS/95656 Outcomes: Disease recurrence (primary, nodal, distant), disease-free survival, overall-survival, presence of PNI and LVI, multi-modal therapy administration. Results XX (est. 50, currently 43) patients were recruited (data to be finalised November 2024). It is predicted WPI V will have high specificity for poor patient outcomes and WPI V cases that were WD- or MD- SCC, are more likely to have poorer outcomes than those that were WPI I-IV. Pearson correlation curves were calculated. Conclusion WPI may serve as a better prognosticator tool for OC SCC, particularly those with WD or MD SCC. This study contributes to emerging evidence for WPI reporting for OCSCC.