Introduction

Oral cavity cancer is one of the most common cancers in India.^[1,2] Carcinoma tongue is the most common site of oral cavity cancer worldwide. The management of carcinoma tongue has been challenging because of its aggressive lymph nodal spread and adverse effects of treatment on Oral and pharengeal function. Advanced disease has a poor prognosis and drastically effects the quality of life. Squamous cell carcinoma is the most common malignancy of the tongue.^[3,4]

Cervical lymph node metastases is the most important prognostic factor in oral cavity cancers.^[5] So the management of cervical lymph node metastases has attained a most important role in the management of carcinoma tongue. The role of prophylactic neck dissection in carcinoma tongue has been a topic of debate since long since its incorporation into the management protocol of carcinoma tongue.^[6,7]

Aims and Objectives

To ascertain the role of prophylactic neck dissection in cN0 tongue cancers

To assess the role of tumour thickness as a guide for the choice type of neck dissection in tongue cancers

Subjects and Methods

A single institutional study by the department of Surgical Oncology in a teritiary care centre. Biopsy of the tumour site has been done and biopsy proven carcinoma tongue cases have been included in the study.

Inclusion criteria

All cases of SCC of anterior 2/3^rd of tongue

Exclusion criteria

Patients of posterior 1/3^rd of tongue malignancies

Patients with lymph node metastasis

Duration: June 2018 to December 2019

A total of 110 cases of carcinoma tongue were recorded. 50 cases out of the 110 cases were cN0. All the cases were operated by wide local excision of primary tumour and modified radical neck dissection. After the histopathological assessment tumours were divided into two categories, tumours with thickness more than 4mm and those with thickness less than 4mm. Pathological node positivity in both these categories is studied. All the cases were followed up and those with positive nodes were advised post-operative radiotherapy.

Results

Among 110 cases studied 50 cases have no clinical nodes at presentation and 60 had cervical lymph node metastases at presentation.

Among the 50 cases with no clinical nodes at presentation, histopathology showed that 20 cases (40%) had primary tumour less than 4mm and 30 cases (60%) had primary tumour more than 4mm.

10 of the 20 cases (50%) with tumour thickness less than 4mm had lymph node metastases on pathological assessment and 24 of the 30 cases (80%) with tumour thickness more than 4mm had lymph node metastases on pathological assessment.

Among the the category of tumor thickness less than 4mm, 4 cases (20%) had lymph node metastases to level 1, 3 cases (15%) had lymph node metastases to level 2, 3 cases (15%) had lymph node metastases to level 3, 1 case (5%) had lymph node metastases to level 4.

Among category of tumour thickness more than 4mm, 10 cases (33.3%) had metastases to level 1, 9 cases (30%) had metastases to level 2, 5 cases (16.6%) had metastases to level 3, 3 cases (10%) had metastases to level 4 and 4 cases (13.33%) had metastases to level 5.

Discussion

Cervical Lymph node metastases is the most important prognostic factor in squamous cell carcinoma of tongue.^[8] The incidence of cervical lymph node metastases in carcinoma tongue is about 40 to 50%.^[9] Identification of patients at risk of cervical lymph node metastases can improve the survival in the patients. Imaging can detect suspected cervical lymph node metastases but its sensitivity has been less.^[10,11] Hisptopathological factors like tumour thickness and grade have been increasingly used as a guide to cervical lymph node metastases.^{[12,13,14,15]}

In our study we had lymph node spread to all levels of cervical lymph nodes in rumours more than 4mm and up to level 4 in tumours less than 4mm thickness. The percentage of nodes involved is clearly in association with tumour thickness. 80 percent of tumours more than 4mm thickness had cervical lymph node metastases whereas only 50 percent of rumours less than 4mm thickness had cervical lymph node metastases. There is multiple level involvement and increased number of nodes involved in association with tumour thickness. There is a definite role of elective prophylactic neck dissection in carcinoma tongue. Based on our study we found that supraomohyoid neck dissection for tumours less than 4mm thickness and modified radical neck dissection for tumours more than 4mm is the most appropriate choice of neck dissection.

Conclusion

The role of neck dissection is the most important step in the management of carcinoma tongue. Prophylactic neck dissection has a definitive role in clinically node negative tongue cancers. Type of neck dissection based on our results showed supraomohyoImid neck dissection would be sufficient for tumours less than 4mm and modified radical neck dissection for tumours more than 4mm thickness. Even most advanced imaging techniques like PET scan and SLNB could not completely derail the need for prophylactic neck dissection in carcinoma tongue.