Malignant Transformation Rate of Oral Submucous Fibrosis: A Systematic Review and Meta-Analysis

Abstract

Oral submucous fibrosis (OSF) is a chronic progressive condition affecting the oral cavity, oropharynx and upper third of the oesophagus. It is a potentially malignant disorder. The authors collated and analysed the existing literature to establish the overall malignant transformation rate (MTR). A retrospective analysis of medical and dental scientific literature using online indexed databases was conducted for the period 1956 to 2021. The quality of the enrolled studies was assessed by the Newcastle-Ottawa Scale (NOS). A meta-analysis using a random effects model of a single proportion was performed along with statistical tests for heterogeneity. The overall proportion of malignancy across all studies was 0.06 (95% CI, 0.02-0.10), indicating an overall 6% risk of malignant transformation across all studies and cohorts. Sub-group analyses revealed strong differences in proportion of malignancy according to ethnicity/cohort; Chinese = 0.02 (95% CI 0.01-0.02), Taiwanese = 0.06 (95% CI, 0.03-0.10), Indian = 0.08 (95% CI, 0.03-0.14) and Pakistani = 0.27 (95% CI 0.25-0.29). Overall, the MTR was 6%; however, wide heterogeneity of the included studies was noted. Geographic variations in MTR were noted but were not statistically significant. Further studies are required to analyse the difference between cohort groups.

Keywords: areca nut; betel nut; malignant transformation rate; oral cancer; oral potentially malignant disorders; oral squamous cell carcinoma; oral submucous fibrosis.

Figure 1

PRISMA flow chart of the screened and included studies.

Figure 2

Comparison of cohort size and percentage of malignancies as reported per study. Logarithmic regression utilised for Indian cases and linear regression for Chinese cases.

Figure 3

Comparison of cohort size and rate of malignant transformation of OSF as reported per study. Linear regression analysis for all data sets.

Figure 4

Forrest plot indicating the proportion of malignant transformation of OSF cases (95% confidence intervals) with weighting (%) attributed to each included case. Meta-analysis was performed on a subgroup basis (according to cohort ethnicity) and on an overall basis (including all data sets) [5,7,8,9,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28].

Figure 5

Funnel plot of the standards errors on the y-axis plotted against the arcsine of the pro-portion on the x-axis. This indicates a broadly symmetrical distribution of studies which suggests a low level of publication bias—there is some study heterogeneity.