Management of neck in clinically node negative, early stage oral cavity squamous cell carcinomas (SCC), especially tongue subsite has been a long-standing controversy. Tumor depth in tongue is shown to predict lymphatic spread but it is difficult to determine pre-operatively and therefore not routinely used in decision-making. We conducted a prospective study to compare the tumor thickness using ultrasonography (USG) and pathological nodal status.
Prospective analysis included 100 patients of early SCC tongue (cT1-T2) with clinically negative neck (cN0), who attended the surgical oncology department at Gujarat Cancer and Research Institute, Ahmedabad, India between September 2013 and September 2015. All the patients underwent USG of tongue pre-operatively to assess the depth of tongue lesion followed by wide local excision of tumor with elective neck dissection (MND). Histopathological findings like pT, pN, differentiation and depth of invasion were compared with pre-op clinical and radiological findings. Relevant statistical tests were used for analysis.
The study had male predominance (62 M: 38 F), with majority in their 5th & 6th decade. Clinically, 44 patients had T1 and 56 had T2 tongue lesion with node negative neck. Pathologically 35 patients were T1 of which 5 had metastatic lymph nodes and 65 were T2 of which 20 had positive nodes. Level II was the most common site for cervical node involvement (48%) followed by level III (28%). Patients were classified according to tumor depth into <2mm, 2-4 mm and >4mm i.e. 22:55:23 sonographically and 20:60:20 histopathologically respectively. Sensitivity of USG for depth< 2mm, 2-4 mm and >4 mm were 100%, 92.3% and 92.3% respectively whereas specificity were 97.6%, 100% and 96.4% respectively. On comparing depth of lesion with node positivity, all the 20 patients with <2 mm depth were node negative, 13 out of 60 with 2-4 mm depth were node positive whereas 12 of 20 with >4 mm depth were node positive. Total 13 patients had recurrence on follow up. Of these, 10 occurred in pN+ patients while 3 in pN0 patients.
Tumor thickness/depth is a significant predictor of nodal metastasis and elective neck dissection should be considered when this depth is 3mm or more. In the present study, ultrasonography was validated as a reliable diagnostic tool in assessing the depth of tumor pre-operatively, with sensitivity and specificity more than 90%.
Tapan Singh Chauhan
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All authors have declared no conflicts of interest.