OP122: Field changes in the clinically normal contralateral mucosa of patients with oral pre-malignant and malignant lesions

Purpose Presence of field cancerization is a major challenge in the management of oral squamous cell carcinomas (OSCC). These multifocal changes are often clinically imperceptible and can occur randomly in areas distant from the primary lesion. The prevalence of field changes in clinically normal contralateral mucosa has not been widely studied. Methods Patients with suspicious oral lesion(s) are evaluated and biopsied at the Oral Cancer Screening Clinic at Roswell Park Cancer Institute. Selected patients with a primary index lesion (IL) that was histopathologically confirmed as oral pre-malignant lesions (OPLs)/OSCC were included in this study. All patients provided a control biopsy from a clinically normal contralateral site. Results Eighty-one patients with IL were identified, 62 with squamous dysplasia (SD), 8 with carcinoma in situ (CIS), and 11 OSCC. Of these, 30 patients (37%) had OPLs/OSCC diagnosed on their contralateral control biopsies (27 mild-SD, 1 moderate-SD, 1 CIS and 1 OSCC). The prevalence of contralateral lesions (CL) was higher in males (45%) when compared to females (27%), though not statistically significant ( p  = 0.09). Other patient factors including age, race, smoking status, alcohol intake, and OSCC history were not predictive of the presence of CLs. Similarly, lesion factors such as location [gingiva (31%) vs. tongue (42%) vs. floor of the mouth (50%), p  = 0.61], IL size [ p  = 0.65], IL clinical appearance [single lesion (37%) vs. multifocal/generalized (35%), p  = 0.87], and IL grade [SD (38%) vs. CIS (26%) vs. OSCC (36%), p  = 0.75] did not predict CLs. Patients with multiple visible OPL/OSCC lesions had greater prevalence of CLs (46%) when compared to single OPL/OSCC (32%), however not statistically significant ( p  = 0.20). Conclusion Over one-third of the patients presenting with OPL/OSCC exhibited unexpected field changes in the clinically normal contralateral sites. Awareness of this fact is important for the treatment planning and follow-up for oral cancer.