"Mirror Image Biopsy:" An Emerging Tool for the Identification of Field Cancerization.

Background: The most dreaded word - "Cancer" - comprises a wide category of diseases that can attack and conquer any part of the body, metastasis being the primary cause of death around the world. Early detection, appropriate care, and treatment of patients play a major role in bringing down the cancer burden leading to a higher chance of cure. Patients debilitated by oral cancer carry a high probability of developing multiple primary tumors due to repeated exposure to carcinogens and this concept is known by field cancerization. Aims and Objectives: This study was carried out to better define the incidence of field cancerization in patients diagnosed with carcinoma in the oral cavity, by histopathological examination of the so-called "mirror image biopsies" and its immunohistochemical evaluation using P53 expression. Materials and Methods: Incisional biopsies were taken from the contralateral oral cavity site of 30 patients histologically diagnosed with OSCC in D Y Patil Dental College and Hospital, Navi Mumbai. The H and E stained OSCC tissues of these patients were histologically graded and tabulated into well-differentiated, moderately differentiated, and poorly differentiated squamous cell carcinoma. The H and E stained "Mirror image" tissues were analyzed histologically to observe for dysplastic changes by three observers. Finally, the p53 stained "Mirror image" tissues were visually analyzed and scored for staining intensity and precentage of positive cells. Results: The OSCC cases were histologically graded and divided using Broder's classification, among which 90% showed well-differentiated squamous cell carcinoma and 10% showed moderately differentiated squamous cell carcinoma. There were no poorly differentiated OSCC cases. The "mirror image" biopsy sites were histologically graded using the WHO classification of oral epithelial dysplasia (2017) which revealed that eighteen patients(60%) showed mild dysplasia, 11 patients (37%) had moderate dysplasia, and 1 patient (3%) revealed severe dysplasia. The p53 stained MIB tissues were visually analyzed out of which 10 were scored as negative, 12 cases as mild, 7 as moderate, and 1 as strongly positive. The histopathological diagnosis of H and E-stained MIB tissues was correlated with the IHC diagnosis of P53-stained MIB tissues. Of 18 mild dysplasia cases, 8 were scored as negative, 7 as mild and 3 as moderate. Similarly, out of 11 moderate dysplasia cases, 1 was scored as negative, 5 as mild, 4 as moderate and 1 as strongly positive. However, the correlation between these two, showed no statistical significance ( Conclusion: all efforts should be made to exclude simultaneously developing multiple primaries at the initial evaluation, as the consequences of missing such a precancerous lesion can be disastrous. OSCC patients must be subjected to a long-term and careful follow-up. Identifying those sites with increased risk for second primary tumors effectively improves early diagnosis and prognosis.