Impact of WPOI-5 on Risk of Regional Recurrence in Early Oral Cancer With pN0 Neck

Introduction: Regional recurrence (RR) has been reported to occur in 7%–17% of patients with oral squamous cell carcinoma (OSCC) and pathologically negative (pN0) necks. Risk factors for isolated RR, in the absence of simultaneous local recurrence, are poorly defined. Our aim was to study risk factors for isolated RR in early OSCC with clinically and pathologically negative necks. Methods: Retrospective cohort study of 202 patients with cT1/2N0 OSCC. Results: Among 130 patients undergoing elective neck dissection, 98 were pN0. Five (5.1%) developed isolated RR, and 7 (7.1%) developed any RR. Risk factors for isolated RR were worst pattern of invasion category 5 (WPOI-5) (p = 0.02), and absence of postoperative radiotherapy (PORT) (p = 0.04). Among 170 patients with pN0 or cN0/x necks, risk factors for isolated RR were WPOI-5 and depth of invasion > 10 mm. On multivariate analysis, only WPOI-5 remained significant. Conclusion: Isolated RR may occur in over 5% of patients with early OSCC and pathologically negative necks after elective ND. WPOI-5 would appear to be the most important risk factor for isolated RR in pN0 cases. Further work is required to define the role of PORT in patients with WPOI-5. Level of Evidence: 3.