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


METHODS
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%).


RESULTS
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).


CONCLUSIONS
These results indicate that patients with pre-malignant oral lesions need long-term follow up.
Hsue
Shue-Sang
SS
Department of Oral Pathology, School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
Wang
Wen-Chen
WC
Chen
Chung-Ho
CH
Lin
Cheng-Chung
CC
Chen
Yuk-Kwan
YK
Lin
Li-Min
LM
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D015331:Cohort Studies; D018450:Disease Progression; D004848:Epithelium / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006965:Hyperplasia; D007972:Leukoplakia, Oral / Q000473:pathology; D017676:Lichen Planus, Oral / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009059:Mouth Diseases / Q000473:pathology; D009062:Mouth Neoplasms / Q000473:pathology*; D009914:Oral Submucous Fibrosis / Q000473:pathology; D011230:Precancerous Conditions / Q000473:pathology*; D013624:Taiwan; D013997:Time Factors; D014860:Warts / Q000473:pathology