OP228: Elucidating risk factors for oral leukoplakia affecting gingivae among a Japanese population

Abstract

Purpose Population screening studies in Japanese have confirmed that oral leukoplakia (OL) affecting the gingivae (gingival leukoplakia: GL) is the most frequent location of OL. We investigated a cohort of patients with GL and their clinic-pathological features were compared with patients with OL affecting other sites (n-GL). Methods Among 204 subjects diagnosed with OL (GL:114, n-GL:90) during 09-11 in 4 city hospitals in Japan, 151(74%) subjects (GL:88, n-GL:63) (age: 64.4 ± 12.7) were recruited. OL was diagnosed by WHO criteria (Warnakulasuriya et al., J Oral Pathol Med, 2007). They were interviewed for risk factors and investigated by patch testing for dental materials, biopsy for dysplasia recording and detection of aldehyde dehydrogenase (ALDH2) polymorphism in saliva by Real-Time PCR for SNP genotyping (rs671) and screened for HPV-DNA by GP5+/6+PCR from paraffin-embedded tissues among selected subjects (n = 31). Results There were no significant differences by age (mean ages: GL, 65.9; n-GL, 62.3) or in tobacco and alcohol use in the two groups. Eighty-one percent of GL were seen in association with prosthesis and 27% close to amalgam fillings. Metal allergy test was positive in 58% of the GL but was not significantly higher compared to the n-GL (41%). Higher dysplasia grades were found in n-GL (P = 0.018). Alcohol intolerance (flush reaction) was higher in n-GL (73%) (P = 0.035). The homozygous ALDH2∗2/2 and 2∗1/2, which work less efficiently in alcohol metabolism was higher in n-GL (55%) than in GL (41%). HPV-DNA was not detected in any of the samples. Conclusions GL had lower dysplasia scores compared to n-GL, but the risk factors appear similar. Oral leukoplakia in n-GL may be associated with aberrant oxidative pathway of alcohol metabolism in Japanese. There was no evidence to support a causal relationship between HPV-DNA detection and GL nor n-GL (Funded by Sasakawa GB Foundation).