A noninvasive genetic screening test to detect oral preneoplastic lesions.

JF Bremmer, BJM Braakhuis, EJ Ruijter Schippers, A Brink, HMB Duarte, DJ Kuik, E Bloemena, CR Leemans,
I van der Waal and RH Brakenhoff.

 

Abstract (Link to PubMed Abstract)

Early diagnosis of oral squamous cell carcinoma (OSCC) may have a major impact on survival and quality of life. Recent studies have shown that the majority of OSCC is preceded by precursor lesions characterized by genetic alterations. The aim of this study was to develop and evaluate a noninvasive screening test for oral preneoplastic lesions, based on genetic alterations as marker. Various methods to obtain a high yield of cells by brushing a small area of the oral mucosa were compared. A novel genetic assay, multiplex ligation-dependent probe amplification (MLPA), was applied that enables the measurement of gains and losses at 40 different chromosomal locations in one PCR reaction using 150 ng DNA. MLPA was performed on DNA of normal and dysplastic oral mucosa as well as of OSCC with the intention to select a specific probe set for accurate detection of precursor lesions in the oral cavity. The assay was correlated to loss of heterozygosity analysis using microsatellite markers, and evaluated on noncancer subjects and patients with oral leukoplakia. A noninvasive sampling method was developed with DNA yields ranging from 150 to 600 ng. Using 120 probes, we could detect large differences with MLPA in the number of alterations between normal vs dysplastic and dysplastic vs tumor tissue with P-values <0.001. A significant correlation was found between the number of alterations as detected by MLPA and the analysis for allelic loss. The available data enabled the selection of a set of 42 MLPA probes, which had the power to optimally discriminate between normal and dysplastic tissue. Our data show that MLPA is a sensitive, reliable, high-throughput and easy-to-perform technique, enabling the detection of genetic alterations on small noninvasive samples and can be considered a promising method for population-based screening of preneoplastic lesions in the oral cavity.Laboratory Investigation (2005) 85, 1481-1488. doi:10.1038/labinvest.3700342; published online 29 August 2005.

 

Editor comment

Oral and pharyngeal cancers cause significant morbidity and mortality, yet there has been little improvement in survival rates in the past 30 years. Despite improved surgical approaches, vastly improved reconstruction techniques, and advances in radiation and medical oncology, the single most effective route to improving the long-term outcome of oral squamous cell carcinoma is early diagnosis.

 

Oral cancer is widely perceived as a heterogeneous group of disorders with markedly different biological properties, which are caused by a series of clonally selected genetic changes in key tumour-suppressor genes, oncogenes and DNA-repair genes.

 

Currently, there are no widely accepted reliable predictors of the outcome in individual patients with oral preneoplastic lesions. However, recent studies have shown that the majority of oral squamous carcinomas are preceded by precursor lesions characterized by genetic alterations. Ploidy analyses have been advocated by Sudbø et al., but the usefulness of this technique which has not yet been confirmed by others.

 

In this paper by Bremmer, et al., a non-invasive screening test for oral preneoplastic lesions, based on genetic alterations as markers, was developed and evaluated. They showed that detection of genetic alterations on small non-invasive samples from the oral mucosa is possible to conduct. Of more importance would be to assess if the method would be useful to predict the development of malignant transformation. Nevertheless, this is an interesting approach and hopefully this and other genetic techniques can be used to identify risk groups of patients with mucosal lesions which will transform into oral squamous carcinomas.