Oral submucous fibrosis transforming into squamous cell carcinoma: a prospective study over 31 years in mainland China.

OBJECTIVE Oral submucous fibrosis (OSF) is an oral mucous disease caused by betel quid chewing. It is controversial whether OSF can transform into oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS In this prospective study, a group of 567 patients with OSF were enrolled from 1986 to 2017 and followed-up until 2019. The cancerous information was collected and analyzed. RESULTS OSF transformed into OSCC in 32 cases (32/567, 5.6%). The patient's age ranged from 20 to 69 years, and the average age was 52 years. The time taken for transformation ranged from 2 to 24 years, the average being 8.6 years. The cancerous transformation occurred in 18 patients (56%) from years 2 to 9, in 13 patients (41%) from years 10-19 and in 1 patient (3%) from 24 years. We analyzed the betel quid chewing habits and found all 32 patients with OSCC-chewed betel quid. Betel quid chewing was most prevalent in patients aged 40-69 years. Sixteen patients had chewed betel quid for 10-19 years (16/32, 50%) and 19 patients (60%) chewed 10-19 slices each day. The OSCC was located in the left or right buccal regions in 23 patients (23/32; 72%) and in the left or right lingual regions in 4 patients (4/32; 12%). Well, moderately and poorly differentiated squamous cell carcinoma was present in 23 patients (23/32; 72%), 4 patients (3/32; 9%), and 5 patients (5/32; 16%), respectively. CONCLUSION Our findings supported that OSF is a real oral premalignant disorder. CLINICAL RELEVANCE The long duration of the transformation from the OSF to OSCC suggests more frequent examinations and corresponding treatments are necessary for OSF patients.