CONCLUSION: The occult metastasis rate for T2 oral cancer can be reduced by ultrasonography (US). Also, the late metastasis rate is considered to be reduced by combining US with frozen section biopsy (FSB) during supraomohyoid neck dissection (SOHND). OBJECTIVES: Early oral cancer has been reported to show occult metastases in 15-53% of patients, but the criteria or methods for the diagnosis of cervical lymph node metastasis are unclear in many studies, and there is no clear definition of occult metastasis. In patients with T2 oral cancer, the diagnosis of lymph node metastasis by US and its pathological diagnosis (pN) after neck dissection were compared to evaluate the usefulness and limitations of US, occult metastasis rate, significance of SOHND as preventive neck dissection, and use of FSB. METHODS: A total of 73 patients with T2 oral cancer were investigated retrospectively. Modified radical neck dissection (MRND) was performed in N+ patients, and SOHND was carried out in N0 patients. FSB was performed in all patients undergoing SOHND. US and pN diagnoses were compared. RESULTS: The occult metastasis rate was 18% when occult metastases were limited to those detected by SOHND and 22% when late nodal recurrences were also included.
CONCLUSION: The occult metastasis rate for T2 oral cancer can be reduced by ultrasonography (US). Also, the late metastasis rate is considered to be reduced by combining US with frozen section biopsy (FSB) during supraomohyoid neck dissection (SOHND). OBJECTIVES: Early oral cancer has been reported to show occult metastases in 15-53% of patients, but the criteria or methods for the diagnosis of cervical lymph node metastasis are unclear in many studies, and there is no clear definition of occult metastasis. In patients with T2 oral cancer, the diagnosis of lymph node metastasis by US and its pathological diagnosis (pN) after neck dissection were compared to evaluate the usefulness and limitations of US, occult metastasis rate, significance of SOHND as preventive neck dissection, and use of FSB. METHODS: A total of 73 patients with T2 oral cancer were investigated retrospectively. Modified radical neck dissection (MRND) was performed in N+ patients, and SOHND was carried out in N0 patients. FSB was performed in all patients undergoing SOHND. US and pN diagnoses were compared. RESULTS: The occult metastasis rate was 18% when occult metastases were limited to those detected by SOHND and 22% when late nodal recurrences were also included.