Improved diagnostics of “concealed” metastases in patients with сТ1–2N0М0 oral squamous cell carcinoma

Introduction. Oral squamous cell carcinoma is associated with a high risk of regional metastasis even in early stages (T1–2N0M0). Morphological examination reveals concealed metastases in 20 % of removed clinically unaffected lymph nodes.Objective – to evaluate the effectiveness of flow cytometry for detection of concealed metastases in sentinel lymph nodes as an indication for cervical lymph node dissection in patients with stage сT1–2N0M0 oral squamous cell carcinoma.Materials and methods. This study included 27 patients, including 13 patients (48.1 %) with stage T1N0M0 cancer and 14 patients with stage T2N0M0 cancer (51.9 %). At the first stage, all participants underwent primary tumor removal and cervical lymph node dissection with sentinel lymph node examination. After mobilization, half of these lymph nodes was used for routine morphological examination followed by immunohistochemical examination, while the second half of them was analyzed using flow cytometry. Then we compared the results obtained.Results. We examined 46 removed sentinel lymph nodes from 27 patients. Conventional histological examination revealed 4 concealed metastases (8.7 %). Polymerase chain reaction allowed us to detect another 16 metastases (37.8 %). Levels I, II, and III lymph nodes were most frequently affected. Flow cytometry demonstrated that 20 % of patients with a <4 mm invasion had concealed metastases, whereas patients with a 4 to 8 mm invasion had concealed metastases in 60 % of cases. Median follow-up time was 20.4 ± 11.7 months (range: 2.2 to 42.5 months; median 19.5 months). All participants were alive during this time. Seventeen out of 27 patients with stage T1–2N0M0 disease (63 %) were found to have concealed metastases, while the remaining ten patients (37 %) had no metastasis. One patient with stage T1N0M0 oral floor squamous cell carcinoma underwent the removal of the primary tumor and sentinel lymph node. Morphological examination and flow cytometry showed no metastatic lesions. After 14.8 months, the patient developed ipsilateral regional CN3 metastasis. The three-year progression-free survival rate was 94.7 ± 5.1 %.Conclusion. Highly sensible and rapid flow cytometry can become the method of choice in the diagnosis of metastases and deciding on cervical lymph node dissection in patients with cN0 disease. The study is still ongoing.