Purpose: The aim of this study was to determine whether tumor depth affects upstaging of the clinically node-negative neck, as determined by sentinel lymph node biopsy with full pathologic evaluation of harvested nodes including step-serial sectioning (SSS) and immunohistochemistry (IHC).
Patients and Methods: One hundred seventy-two patients with cT1/2 N0 squamous cell carcinoma (SCC) of the oral cavity/oropharynx undergoing primary resection and either sentinel node biopsy (SNB) or SNB-assisted neck dissection as a staging tool for the cN0 neck. Harvested nodes were examined with hematoxylin-eosin staining, SSS, and IHC. Patients upstaged by SSS/IHC were denoted pN1mi.
Results: One hundred one of 172 patients were staged pN0, with 71 (41%) patients upstaged. Increasing tumor depth was associated with higher likelihood of upstaging (P < .001). Tumor depth showed a positive correlation with nodal stage according to TNM classification (P < .001). Tumor depth greater than 4 mm appears to be the most appropriate cutoff for risk stratification, although tumors in the oropharynx may require a lower value.
Conclusion: Tumor depth is an important prognostic factor for patients with SCC of the oral cavity or oropharynx. Tumors greater than 4 mm are associated with greater risk of upstaging; however, this optimum cutoff value may vary between primary tumor sites.