Abstract
ObjectiveThe localization pattern of metastatic sentinel lymph node (SN) and non-SNs and pathologic analysis of metastatic lymph nodes in SN lymphatic basin dissection (SLBD) were investigated in patients with cT2/T3cN0 oral squamous cell carcinoma (OSCC). MethodsThis prospective multicenter trial involved 10 institutions nationwide in Japan. A total of 57 patients were enrolled. The lateral neck was divided into 5 lymphatic basins. The lymphatic basin containing SNs was defined as the SN lymphatic basin.All patients underwent SLBD with backup selective neck dissection (I-III) combined with primary tumor removal. When SNs were found outside of levels I-III, including in the contralateral neck, SLBD was performed by removing the compartments containing SNs separately. SN metastasis was classified as isolated tumor cells (ITCs), micrometastasis, or macrometastasis. ITCs are defined as a lesion no larger than 0.2 mm in largest dimension and are classified as pN0. ResultsSN metastasis was observed in 22 cases. All metastatic lymph nodes, including false-negative cases, were detected in the SN lymphatic basin. Isolated tumor cells in the SNs did not affect prognosis, whereas micrometastasis tended to have poor prognosis.After adjusting for other risk factors, a positive SN remained a significant predictor of poor 5-year overall survival in pT2-4 OSCC. ConclusionSLBD for intraoperative SN biopsy is a sufficient therapeutic procedure and is valuable for determining pathologic nodal stage in OSCC. SN positivity was demonstrated to be an independent predictor of poor prognosis in patients with pT2-4 disease undergoing SLBD with backup selective neck dissection (I-III).
Highlights
There has been extensive debate about neck dissection in clinically N0 oral squamous cell carcinoma (OSCC), and it remains controversial whether the appropriate treatment strategy is watchful waiting, elective neck dissection (END), or sentinel lymph node biopsy (SNB) [1,2,3,4,5]
SN positivity was demonstrated to be an independent predictor of poor prognosis in patients with pT2-4 disease undergoing SN lymphatic basin dissection (SLBD) with backup selective neck dissection (I-III)
A prospective randomized controlled trial demonstrated that clinical T1/T2 OSCC patients who underwent ipsilateral END at the primary surgery had better disease-free survival (DFS) and overall survival (OS) than those who underwent therapeutic node dissection [6]
Summary
There has been extensive debate about neck dissection in clinically N0 (cN0) oral squamous cell carcinoma (OSCC), and it remains controversial whether the appropriate treatment strategy is watchful waiting, elective neck dissection (END), or sentinel lymph node biopsy (SNB) [1,2,3,4,5]. A prospective randomized controlled trial demonstrated that clinical T1/T2 OSCC patients who underwent ipsilateral END at the primary surgery had better disease-free survival (DFS) and overall survival (OS) than those who underwent therapeutic node dissection (watchful waiting followed by neck dissection for nodal relapse) [6]. END is effective for controlling neck metastasis in patients who might subsequently develop occult neck metastasis. A recent phase III trial and a non-inferiority/equivalence study in early OSCC demonstrated that SNB is oncologically equivalent to END in cT1/T2cN0 OSCC [11, 12]
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