Is It Feasible To Perform Sentinel Lymph Node Biopsy With Only Blue Dye In Early Oral Cancer? A Large Cancer Center Experience.

Background: Oral cavity squamous cell carcinoma is one of the most common cancers in south Asia. Sentinel lymph node biopsy has a good accuracy using combination of lymphoscintigraphy and blue dye technique in oral cancer; however, the limited availability of lymphoscintigraphy facilities in many developing countries requires exploration of alternative techniques. The need for the present study was to evaluate the feasibility and role of sentinel lymph node biopsy in identifying the occult lymph node metastasis using methylene blue dye alone. Material and methods: We conducted a prospective study in 94 patients with early oral cancer (cT1, T2 and cN0) in a high volume tertiary care cancer centre in North India from 2013 to 2016. Patients having negative neck nodes on clinical examination and ultrasound were included in study. Intra operatively, one ml of methylene blue dye was injected at the interface of tumor and palpable normal tissue in four quadrants. After 10-15 minutes incision in neck was given and any visualized blue nodes were dissected and sent for frozen section, routine histopathology and immunohistochemistry (IHC) for cytokeratin. Elective neck dissection was done in all patients as per institutional protocol. Results: A total of 94 patients (79.8% male and 20.2% female) with mean age of 46.23 years (range 20-77 years) were included in this study. Smokeless tobacco was the commonest risk factor. Tumor sub sites were tongue (45.7%), buccal mucosa (38.3%), and lip (16%). Identification rate of sentinel lymph node was 93.61% with mean blue node (1.83±1.03). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy for frozen section and histopathology were 84.6%, 100%, 100%, 93.9% and 95.5% respectively. IHC detected two micrometastases and one isolated tumor cells. Occult lymph node metastasis was seen in 27.6% cases. The lymph node distribution was as level IA (5.7%), IB (48.6%), IIA (37.1%), and III (8.6%). None of the patient had lymph metastasis to level IV or V. Majority of the patients (57.4%) had pathological T2 disease. We did not encountered anaphylactic or allergic reactions to methylene blue dye in our study. Surgical procedures performed were as wide local excision only (84%), WLE with or without marginal or segmental mandibulectomy (14.9%), SOND (42.6%), ESOND (45.7%), MND (11.7%), and bilateral neck dissection (7.4%), reconstruction with local flaps (34%). Pathological TNM stage was as T1 (46.8%), T2 (53.18%), N1 (23.4%) and N2 (5.31%). Conclusion: Thus we conclude that SLNB with blue dye alone in early oral cancer is feasible. It can be used successfully with good sensitivity and negative predictive value in limited resource countries like India. Immunohistochemistry contributes to SLNB increasing sensitivity and negative predictive value to improve diagnostic value. [ABSTRACT FROM AUTHOR]

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