Importance: Reports characterizing clinical and histologic features associated with a higher risk for development of malignant lesions in the background of an oral potentially malignant disorder have largely reflected East Asian populations. Long-term studies among the North American population are rare.
Objective: To evaluate risk of malignant transformation (MT) of oral dysplastic lesions by investigating the demographic, social, clinical, and histologic factors that may be associated with an increased rate as well as a decreased time to MT.
Design, setting, and participants: This was a retrospective cohort study with medical record review at a single institution from January 1, 2000, to December 31, 2019, with follow-up for 20 years. Patients were excluded if they were younger than 18 years, the first biopsy diagnosis showed cancer, biopsies were never performed, biopsies were taken from sites outside of the oral cavity, there was no additional follow-up after the first visit, or the biopsy specimen was not characterized on the spectrum of dysplasia.
Exposures: Diagnosis of leukoplakia of oral mucosa, unspecified lesions of oral mucosa, or other disturbances of oral epithelium.
Main outcomes and measures: Main outcome measures included MT rate and time to MT as well as demographic, social, clinical, physical, and histologic features associated with MT.
Results: Thirty-eight of 264 lesions (14%) in 241 patients (132 men and 109 women; mean [SD] age, 64 [13] years) underwent MT. Of the 38 lesions that underwent MT, 19 (50%) underwent transformation by 424 days, 28 (75%) by 870 days, and 34 (90%) by 1600 days. Nodularity, friability, and mass effect were more commonly observed in malignant lesions (nodularity: 42.9% vs 10.0%; difference, 32.9%; OR, 6.72; 95% CI, 3.03-14.89; friability: 42.9% vs 12.8%; difference, 30.1%; OR, 5.11; 95% CI, 1.66-15.69; mass effect: 54.2% vs 10.4%; difference, 43.8%; OR, 10.16; 95% CI, 4.12-25.09). Men were less likely than women to have multiple lesions in the oral cavity (OR, 0.40; 95% CI, 0.22-0.74). Having multiple abnormal sites was associated with higher percentage of MT (OR, 3.38; 95% CI, 1.63-7.01).
Conclusions and relevance: In this cohort study, nodularity and mass effect were associated with lesions that may push, displace, or invade surrounding tissue, and these were more likely to be present in oral dysplastic lesions that ultimately progressed to cancer. There may be less utility in continuing surveillance beyond 5 years.