Malignant transformation in 1458 patients with potentially malignant oral mucosal disorders: a follow‐up study based in a Taiwanese hospital

TLDR

Cancer of the oral mucosa typically follows a non‑invasive precursor lesion. This follow‑up study aimed to estimate the rate and timing of malignant transformation in patients with potentially malignant oral epithelial lesions in southern Taiwan. A cohort of 1,458 patients with various pre‑malignant lesions, average age 47.5 years, was followed from 1991 to 2001, with lesions classified into six histological categories and monitored for progression to cancer. During a mean follow‑up of 42.64 months, 44 patients (3.02 %) progressed to oral cancer, with higher rates in dysplastic lesions (8/166) and hyperkeratosis/epithelial hyperplasia (15/423), underscoring the need for long‑term surveillance.

Abstract

It is generally accepted that the development of cancer in the oral mucosa is preceded by an identifiable non-invasive precursor lesion. The aim of this follow-up study was to estimate the rate and the time to transformation in a group of patients from southern Taiwan with potentially malignant oral epithelial lesions.The follow-up time is defined as the duration between the onset of the initial diagnosis and the occurrence of confirmed oral cancer. A total of 1458 patients with histological diagnoses of various pre-malignant oral lesions were followed up between 1991 and 2001. The average age at initial diagnosis was 47.5 years. The histological diagnoses were divided into six categories: epithelial dysplasia with hyperkeratosis/epithelial hyperplasia (8.85%); epithelial dysplasia with submucous fibrosis (2.54%); submucous fibrosis (27.57%); hyperkeratosis/epithelial hyperplasia (29.01%); lichen planus (9.80%) and verrucous hyperplasia (22.22%).Within the cohort of 1458 patients, 44 patients progressed to oral cancer in the same site as the initial lesions with an overall transformation rate of 3.02% and a mean follow-up time of 42.64 months. Eight of the 166 patients with dysplastic lesions and 15 of 423 patients with hyperkeratosis/epithelial hyperplasia progressed to malignancy. The other patients with malignant transformation originated from various pre-cancerous oral lesions and conditions (submucous fibrosis, eight of 402; lichen planus, three of 143; verrucous hyperplasia, 10 of 324).These results indicate that patients with pre-malignant oral lesions need long-term follow up.