Risk Factors Associated with Malignant Transformation of Oral Epithelial Dysplasia: A Retrospective Review

Abstract

Oral epithelial dysplasia (OED) is regarded as a potentially premalignant lesion; however, there is no general consensus on the malignant transformation rate or the associated risk factors.1 The purpose of this study is to report on the malignant transformation rate of OED in a tertiary care center and perform an analysis of potential clinical and histologic risk factors to better predict which lesions will transform. A retrospective chart review was performed for all patients with a diagnosis of OED at Sunnybrook Health Sciences Centre in Toronto, ON, Canada, between 2015 and 2018. Each case was assessed for malignant transformation, as well as potential risk factors. An array of statistical analyses was performed to determine the association of a multitude of clinical and histologic risk factors on outcomes. Of the 201 patients who presented with OED, 17% (34) transformed into oral squamous cell carcinoma with an average time to transformation of 33.4 months (range: 1-149 months). Seven cases had no dysplasia (hyperkeratosis) at the initial biopsy, and 12 showed only mild dysplasia. The most common site of transformation was the ventrolateral tongue (41%), followed by the buccal mucosa (29%). No significant difference was noted in malignant transformation between genders (18 male and 16 female). Risk factors were divided into 2 broad categories: lesion-specific factors (clinical appearance, location, multifocality, degree of dysplasia, and molecular characteristics) and patient-specific factors (smoking, alcohol consumption, smokeless tobacco/betel-quid use, and immunodeficiency). Beyond the well-described risk factors including smoking and alcohol and betel-quid use2, our results show both local and systemic factors that are associated with progression. We emphasize the importance of risk factor analysis in patients with a histologic diagnosis of low-grade dysplasia as close surveillance in these cases is otherwise less emphasized. It is important to understand that risk factors are dynamic, and if a patient’s risk profile changes, closer follow-up may be warranted for lesions with minimal or no dysplasia.