COMPARISON OF CLINICAL AND PATHOLOGICAL STAGING INCORPORATING DEPTH OF INVASION IN ORAL CARCINOMA

Abstract

BACKGROUND: Head and neck cancers account for about 30% of malignancies in our country. Among them, about 50% are oral cancers. Around 80-90% of oral cancers are directly attributable to tobacco use which is the major predisposing factor for oral malignancy. The growing numbers of oral malignancy gives us a dire need to strengthen the diagnostic and management protocol of the mass. The treatment options as well as prognosis of these patients depends on the TNM Staging as outlined by AJCC. The 8th Edition of AJCC Staging incorporates a 3rd dimension- ―Depth of Invasion‖ which has posed a new challenge for pre treatment staging of oral cancer, as histopathological examination of the resected specimen has been the gold standard for assessing the depth of invasion. Moreover, the difficulty in accurately assessing the depth of invasion pre treatment by clinical examination and imaging as well as incorporating depth makes pre treatment staging difficult and can differ from pathological staging. The difficulties that arise in case of clinical assessment of depth of invasion like trismus, difficult accessing of posterior part of oral cavity, complex anatomy of subsites like hard palate, retromolar trigone where soft tissue is less and reaches bone soon after it crosses mucosa or periosteum. The difference in the Clinical and Pathological Staging may require a re-look or modification in the management options, particularly with regard to adjuvant treatment. xvii OBJECTIVES: 1. To Stage the primary tumor in oral cavity by clinical examination and contrast enhanced computed tomography incorporating the greatest diameter and the depth of invasion in squamous cell carcinoma of oral cavity staged T2 to T4. 2. To stage the primary tumor by histopathological examination of the resected specimen incorporating the tumor dimensions and depth of invasion in squamous cell carcinoma of oral cavity staged T2 to T4. 3. To compare the clinical, radiological and pathological staging in the above tumors and to document the implications on treatment and outcome METHODS: The study included 75 patients with biopsy proven oral carcinoma staged T2 to T4 according to AJCC classification (8th edition) at R.L. Jalappa Hospital And Research Centre, Kolar from December 2018 to November 2020. Clinical and radiological assessment of Depth of invasion was documented preoperatively by means of clinical palpation and CECT respectively, and clinical staging was established. Postoperatively, pathological Depth of invasion was noted and pathological staging was done. Subsite wise analysis was done of DOI as well as Staging. RESULTS: This cross sectional comparative study done in Kolar, had 79% of patients as female, with majority of patients ranging in the age group 51-60 years. The most common site involved was Buccal mucosa and lower GBS due to the usage of quid in those areas overnight. xviii The bone involvement was noted in 4 patients in CT scan whereas histopathological bone invasion was noted in 8 patients. The comparison of clinical, radiological and histopathological DOI was done subsite wise. In buccal mucosa, DOI was underassessed in 4 patients in lesions with DOI<10mm, whereas overassessed in 2 patients with DOI>10mm. 2 patients were downstaged in T stage. In subsite alveolus, 3 patients showed minor discrepancy in Depth of invasion, and 2 patients showed discrepancy in the T staging. In anterior 2/3rd tongue, 4/9 patients showed discrepancy in the assessment of Depth of invasion. In subsite Retromolar trigone, 2/6 patients showed minor discrepancy in DOI assessment. In Nodal staging, 2 patients were upstaged to N3b due to Extracapsular extension, whereas 2 were upstaged to N2b. 19 patients were downstaged from clinical to pathological staging. CONCLUSION: There may be significant difference in the DOI assessed clinically when compared to histopathology, thereby affecting treatment planning and outcome. Also, there are certain sites where mucosa lies over the periosteum, making it difficult for the assessment of the DOI.