SENTINEL LYMPH NODE BIOPSY AS A PROGNOSTIC TOOL IN EARLY ORAL CANCER USING METHYLENE BLUE DYE

Abstract

Introduction: Limited availability of lymphoscintigraphy facilities in Egypt and developing countries requires exploration of alternative methods of SLN detection. Sentinel Lymph Node (SLN) biopsy using a combination of radioisotopes and methylene blue dyes (MBD) have a good accuracy rate in predicting subclinical neck nodal metastases in head and neck cancers. Objectives: Evaluation of the effectiveness of SLN using MBD alone and frozen section of early oral cancer with N0 neck patients in the identification of occult neck micrometastasis and confirmation of the role of SLN in post-surgical follow up. Materials and methods: 12 Patients with cN0 early (T1, T2) oral squamous cell cancers underwent SLN biopsy using peri tumoural MBD injection. Stained SLN nodes were sent for frozen section analyses. Patients had microscopic metastases in SLN underwent modified radical neck dissections and the rest underwent selective neck dissections. Paraffin sections were performed in all cases and immune-histochemistry (IHC) studies were performed on negative lymph nodes. Results: Three cases (25%) SLN couldn't be detected, while nine cases (75%) the blue sentinel lymph node could be identified. Preoperative ultrasound examination of only two cases were not similar to the intraoperative frozen histopathology which reveals the presence of micrometastasis, therefore functional neck dissection was indicated in these two cases and all the frozen sections histopathology were similar to the postoperative paraffin sections. Considering HPE on paraffin fixed blocks as the gold standard, FS had a sensitivity, specificity, and NPV of 95.8 %. IHC with cytokeratin increased the sensitivity (100 %) and NPV (100 %) of histopathology at the loss of specificity (87.5 %) and PPV (62.5 %). Conclusion: SLN biopsy is useful and reliable for patients with early oral cancer that can benefit from reducing unnecessary functional and esthetic complications for N0 patients by reducing the incidence or extent of neck dissection.