Association between Predictors of Oral Potentially Malignant Disorders and Time to Malignant Transformation: a Cohort Study in Taiwan

• Main Authors: Chia-Yu Wong, 翁佳瑜
• Other Authors: 陳信銘
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/77547170801897972006

碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 100 === Background Oral potentially malignant disorders (OPMDs) were all clinical presentations that carry a risk of developing oral squamous cell carcinoma (OSCC). The aim of the study was to identify the natural history of OPMDs with different histological diagnosis, and correlate the outcome of malignant development with interventions corresponded to histological diagnosis in patient with OPMDs. Material and method The retrospective cohort study included patients with biopsy-confirmed OPMDs seen at National Taiwan University Hospital from July 1997 to June 2008 and followed until December 2010. The patients’ clinical and medical variables were identified from medical record, including date of birth, gender, personal habit, clinical presentation of OPMD, histological diagnosis with degree of epithelial dysplasia graded as none, mild, moderate or severe, and management. The outcome of interest was transformation to oral squamous cell carcinoma or oral verrucous carcinoma. To avoid co-existing malignancies, subjects were included 6 months after the date of the index biopsy. Kaplan–Meier estimates and Cox proportional hazard regression were undertaken to explore the simultaneous effects of multiple factors associated with transformation to oral cancer. Result There were 2193 patients included in the study. The majority of patients were men (84.5%), and 84.4% were over 33 years of age. Among all OPMDs, squamous hyperplasia was the most common histological diagnosis (48.1%), and 712 (32.5%) had oral epithelial dysplasia (45 severe, 346 moderate and 321 mild). One hundred and sixty-eight patients (7.7%) developed oral cancer over the follow-up period of 13 years. There was an association between histological diagnosis and time to transformation after adjustment. Patients with oral verrucous hyperplasia or moderate or severe dysplasia had higher hazard of transformation to oral cancer compared to those without dysplasia (HR were 4.1, 3.7, and 5.2, respectively). The association between blade surgery and time to transformation was also significant although attenuated (HR was 0.4). This significance of decreased hazard remained for patients who were diagnosed as having no dysplasia, mild to moderate dysplasia, and verrucous dysplasia. Conclusion OPMD lesions can be categorized as group with lower hazard (no dysplasia and mild dysplasia) and group with higher hazard (moderate to severe dysplasia and verrucous hyperplasia) to malignant transformation. Since both of them are at risk of developing cancer, blade surgery should be performed to reduce the hazard of malignant transformation.