Oral leukoplakia, oral submucous fibrosis and erythroplakia
are 3 major types of oral premalignant lesions. Multiple
oral premalignant lesions may possibly develop due to field
cancerization, where carcinogenic exposures can cause simultaneous
genetic defects to the upper aerodigestive tract
epithelium, putting the epithelium at high risk for development
of premalignant lesions at different stages of carcinogenesis.
There have been no epidemiological studies on risk
or protective factors of the disease. A case-control study was
conducted with data from the baseline screening of a randomized
oral cancer screening trial in Kerala, India. A total of
115 subjects with multiple oral premalignant lesions (8–10%
of oral premalignant lesions in our case series) were included:
64 subjects with oral leukoplakia and oral submucous fibrosis,
19 subjects with oral leukoplakia and erythroplakia, 22 subjects
with oral submucous fibrosis and erythroplakia and 10
subjects with all 3 lesions. Individuals without oral lesions
were considered controls (n47,773). The odds ratio (OR)
for ever tobacco chewers was 37.8 (95% confidence interval
(CI)16.2–88.1) when adjusted for age, sex, education, BMI,
smoking, drinking and fruit/vegetable intake. Dose-response
relationships were seen for the frequency (p