Comparison of pre-operative ultrasonic depth of invasion (DOI) with histopathological depth of invasion (DOI) in gingivobuccal sulcus squamous cell carcinoma with neck nodal metastasis

Abstract

Introduction: Head and neck carcinomas have the highest incidence among other carcinomas in the several regions of the country with trends still rising in the third population. The tumor mass is not planar but rather grows three-dimensionally, so surgeons should have the knowledge of the third dimension, which is the depth of invasion (DOI). Nowadays advanced techniques have been introduced to measure the preoperative depth of invasion of the primary tumor, i.e., ultrasonography (USG) scans. Ultrasonography (USG) scan is still considered a preoperative gold standard to measure DOI because of its advantages of radiation-free imaging and excellent tumor visualization, economical, non-invasive, and real-time images that can be obtained spontaneously. The primary objective of the study was to evaluate and compare pre-operative ultrasonic depth of invasion (DOI) with histopathological DOI in gingivobuccal sulcus squamous cell carcinoma with neck nodal metastasis.

Materials and methodology: This is a single-center prospective study including 51 patients reporting to our unit from November 2019 to November 2021 who were subjected to surgery. Preoperative USG evaluation of lesion was performed on all patients which recorded DOI.Similarly, postoperatively, all the resected specimens were examined for the histopathological DOI.The value obtained preoperatively from USG examinations was then compared with histopathological DOI postoperatively. Correlation coefficient analysis was studied using a scatter diagram by Karl Pearson and a dependent t-pair test. A chi-square with Yates's correction test was used to study the statistical association between USG DOI and lymph node metastasis (LNM).

Results: A total of 51 patients were included in the study of which 40(78.4%) were male patients and 11(21.6%) were female patients. DOI measured preoperatively from the USG scan in these cases ranged from 6 mm to 37 mm with an average of 19.41 mm. Histopathological DOI measured in all these patients ranged from 1.3 mm to 16 mm with an average of 7.26 mm. A statistical significance was noted between preoperatively measured DOI from the USG scan and postoperatively (histologically) measured DOI with a p-value of 0.0316. Cervical lymph node metastasis was USG positive in 15 (29.41%) patients out of 51 patients. Chi-square test with Yates's correction = 0.2721, P = 0.6020, noted association between the USG DOI and the occurrence of the cervical lymph node metastasis.

Conclusion: DOI is clearly a potentially useful and objectively measurable prognostic tool. USG imaging studies are used preoperatively to locate the extension of the lesion proper and to measure the area of the deepest invasion of the tumour. Preoperatively, DOI data obtained helps the surgeon to plan 3-dimensional clearance of the disease. Although USG scans lack in early detection of bone invasion in gingivo buccal sulcus carcinoma, could be a adjuvant rapid axillary scan in determining the third dimension of tumor that is DOI and cervical lymph node metastasis.

Keywords: Depth of invasion (DOI); Gingivo buccal sulcus (GBS); Oral squamous cell carcinoma (OSCC); Ultrasonography (USG).