Attempting to define sentinel node micrometastasis in oral squamous cell carcinoma.

OBJECTIVE The aim of this supplemental study of a sentinel node (SN) biopsy (SNB) trial for oral squamous cell carcinoma (OSCC) was to assess the effectiveness in identifying micrometastasis and determining whether elective neck dissection (END) is necessary. MATERIALS AND METHODS Twenty-three patients with pathologically positive SNs were included. The sizes of the metastatic lesions in positive SNs (SMSNs) were classified and the rates of occult metastasis of non-SNs were compared. RESULTS The patients were divided according to the SMSN:<0.2 mm (group A, n=3);0.2 mm to <2.0 mm (group B, n=7);and ≥2.0 mm (group C, n=13). The rates of occult metastasis in groups A, B, and C were 0% (0/3), 14% (1/7) and 23% (3/13), respectively. CONCLUSION Rare cancer cell distribution to nodes other than SNs was observed in the patients with SN metastatic lesions of at least smaller than 0.2 mm in size, suggesting the possibility of defining SN micrometastasis in N0 OSCC.