The prevalence of occult metastases in nonsentinel lymph nodes after step‐serial sectioning and immunohistochemistry in cN0 oral squamous cell carcinoma

Abstract

To examine the prevalence of isolated tumor cells (ITC) and micrometastases (MM) in nonsentinel lymph nodes (NSN) using additional step-serial sectioning and immunohistochemistry (IHC) as for sentinel lymph nodes (SN). Prospective, consecutive, and clinically controlled trial. Fifty-one patients with oral cavity squamous cell carcinoma (OSCC) T1-T2 and clinically N0 neck underwent surgical treatment including sentinel-node biopsy (SNB) assisted selective neck dissection (SND). The location of the SN was determined using dynamic and planar lymphoscintigraphy and SPECT-CT. The harvested NSN from the neck dissections underwent the same histopathologic examinations as the SN using step-serial sectioning (SSS) at 150-micron intervals. Two sections from each level were stained with hematoxylin-eosin (H&E) and cytokeratin antibodies (AE1/AE3) and examined for tumor deposits. Results were compared with the previous routine examination of the NSN. A total of 403 NSN were examined with a median of 8 per patient. A total of 1/51 patients (2%) had involvement of an additional NSN not found on routine examination. This was the only lymph node with involvement not detected previously. However, this patient had metastases in SN and in another NSN detected on routine examination. The overall incidence of occult metastasis (SN + NSN) was 21.6% (11/51) as previously reported. The incidence of occult metastases in NSN after additional SSS and IHC was 2%. The risk of NSN involvement would seem to be extremely low in patients with early OSCC and negative SN. This study further validates SNB as an accurate staging tool for cN0 early OSCC.