Evaluation of the 10 %-rule in sentinel lymph node biopsy for clinically node-negative oral squamous cell carcinoma

Roosmarijn S Tellman ¹, Dominique N V Donders ¹, Rutger Mahieu ¹

⁰Department of Head and Neck Surgical Oncology, University Medical Center Utrecht, the Netherlands.

Oral Oncology +

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November 21, 2024

View abstract on PubMed

Summary

The 10%-rule effectively identifies metastatic sentinel lymph nodes in early-stage oral cancer. Applying this rule per neck side is recommended, but increasing the threshold is not advisable for accurate staging.

Area Of Science

Oncology
Surgical Pathology

Background

Sentinel lymph node biopsy (SLNB) is crucial for staging early-stage oral squamous cell carcinoma (OSCC).
The 10%-rule defines sentinel lymph nodes (SLN) intraoperatively based on gamma counts relative to the hottest lymph node (LN).
The intraoperative accuracy of the 10%-rule in OSCC requires further evaluation.

Purpose Of The Study

To evaluate the intraoperative performance of the 10%-rule in early-stage OSCC.
To explore potential modifications or alternative criteria for SLN identification.

Main Methods

Retrospective analysis of 66 patients with clinically node-negative OSCC and positive SLNB (2014-2023).
Ex-vivo measurement of radioactivity in all harvested LNs.
Assessment of metastatic LNs against the 10%-rule and evaluation of alternative thresholds.

Main Results

Out of 233 LNs, 98 were metastatic and 190 met the 10%-rule.
The 10%-rule correctly staged 69 of 70 metastatic neck sides.
Increasing the threshold to 20% correctly staged 68 sides but excluded 18 LNs; applying the rule per side identified one additional metastatic LN not affecting upstaging.

Conclusions

The 10%-rule is effective for intraoperative identification of metastatic SLNs in OSCC.
Consideration of applying the 10%-rule on a per-neck-side basis is recommended.
Increasing the threshold percentage beyond 10% is not advised.

Keywords:

10%-rule Oral squamous cell carcinoma Sentinel lymph node biopsy