The risk and interval to malignancy of patients with laryngeal dysplasia; a systematic review of case series and meta-analysis

BACKGROUND: Laryngeal dysplasia is a pre-malignant condition with wide variability in rates of malignant transformation reported in the literature. The management and follow-up strategies of these lesions vary widely.

OBJECTIVES: To assess the risk of and interval to malignant transformation in patients with laryngeal dysplasia, the effect of different treatment modalities on malignant transformation and the effects that risk factors such as smoking, excessive alcohol intake and histological grade may have on this.

TYPE OF REVIEW: Systematic of observational studies with attempted meta-analysis.

SEARCH STRATEGY: A structured search of Medline (1966 to January 2010), EMBASE (1980 to January 2010), CINAHL (1981 to January 2010) and Cochrane databases (CENTRAL, Cochrane Library, 1995 to January 2010).

RESULTS: Nine hundred and forty cases from nine studies were included in the analysis. Overall malignant transformation rate was 14% (confidence interval 8, 22) and mean time to malignant transformation was 5.8 years. The malignant transformation rate is higher with increased severity of dysplasia grade - severe/CIS 30.4%versus mild/moderate 10.6% (P < 0.0002). Treatment modality did not show significant effects.

CONCLUSIONS: Laryngeal dysplasia carries a significant risk of malignant transformation. This risk triples with increasing severity of dysplasia. Transformation often occurs late and is not related to the grade of dysplasia. There is little evidence, therefore, to support the early discharge of patients with mild/moderate dysplasia, which is practised by some clinicians.