Comparison of the Cytobrush®, dermatological curette and oral CDx® brush test as methods for obtaining samples of RNA for molecular analysis of oral cytology

M. D. Reboiras-Lopez, M. Perez-Sayans, J. M. Somoza-Martin, P. Gayoso-Diz, F. Barros-Angueira, J. M. Gandara-Rey and A. Garcia-Garcia Comparison of the Cytobrush (R), dermatological curette and oral CDx (R) brush test as methods for obtaining samples of RNA for molecular analysis of oral cytology Objective: Interest in oral exfoliative cytology has increased with the availability of molecular markers that may lead to the earlier diagnosis of oral squamous cell carcinoma. This research aims to compare the efficacy of three different instruments (Cytobrush, curette and Oral CDx brush) in providing adequate material for molecular analysis. Methods: One hundred and four cytological samples obtained from volunteer healthy subjects were analysed using all three instruments. The clinical and demographical variables under study were age, sex and smoking habits. The three instruments were compared for their ability to obtain adequate samples and for the amount of RNA obtained using quantitative real-time polymerase chain reaction (PCR-qRT) analysis of the Abelson (ABL) housekeeping gene. Results: RNA of the ABL gene has been quantified by number of copies. Adequate samples were more likely to be obtained with a curette (90.6%) or Oral CDx (80.0%) than a Cytobrush (48.6%); P < 0.001. Similarly, the RNA quantification was 17.64 +/- 21.10 with a curette, 16.04 +/- 15.81 with Oral CDx and 6.82 +/- 6.71 with a Cytobrush. There were statistically significant differences between the Cytobrush and curette (P = 0.008) and between the Cytobrush and OralCDx (P = 0.034). There was no difference according to the demographical variables. Conclusions: Oral exfoliative cytology is a simple, non-invasive technique that provides sufficient RNA to perform studies on gene expression. Although material was obtained with all three instruments, adequate samples were more likely to be obtained with the curette or Oral CDx than with a Cytobrush. The Oral CDx is a less aggressive instrument than the curette, so could be a useful tool in a clinical setting.