Neck observation is appropriate in T1-2, cN0 oral squamous cell carcinoma without perineural invasion or lymphovascular invasion

Objectives Management of cN0 neck, elective neck dissection (END) or observation, remains controversial for T1-2 oral squamous cell carcinoma (OSCC). To allow for the safe observation of cN0 neck, it is mandatory to define predictors with high negative predictive value (NPV) for cervical lymph node (LN) status. Materials and Methods Pathologic re-evaluation was performed in tumors of 253 consecutive patients with T1-2, cN0 OSCC. The predictive roles of pathologic parameters for cervical LN status in guiding neck management were investigated. Results Cervical LN metastasis (LN+) occurred at a similar rate between observation and END groups (20.8% vs. 22.2%, p = 0.807), indicating poor discriminatory value for cervical LN status by clinical judgment. Compared with T classification, tumor thickness and differentiation, PNI/LVI (perineural invasion/lymphovascular invasion) demonstrated the highest NPV (85.5%). Hypothetically using PNI/LVI status to guide neck management, a dramatic reduction in overtreatment rate could be achieved (54.2% to 20.2%), with a minimal increase in undertreatment rate (6.3% to 9.9%). In patients without PNI or LVI (PNI/LVI-), the ultimate neck control rate (96.9% vs. 96.3%, p = 1.000) and 5-year disease-specific survival rate (91.1% vs. 92.8%, p = 0.863) were equivalent between observation and END. However, a significantly higher incidence of neck recurrence was found with observation (16.9% vs. 6.5%, p = 0.031), with 93.8% occurring within one year and 73.3% being successfully salvaged. Conclusion Observation under close follow-up for the first year is appropriate in T1-2, cN0 OSCC without PNI or LVI, for the achievement of equivalent ultimate neck control and 5-year disease-specific survival rates compared with END.