Challenges and opportunities of next-generation sequencing: a cytopathologist's perspective

Molecular cytopathology has gene sequencing as its core technology. Until recently, cytological samples were only tested by sequential single-gene mutational tests. Today, with the better understanding of the molecular events involved in malignancy and the mechanisms of pharmacotherapy, larger gene panels are more informative than a single biomarker. Next-generation sequencing (NGS), matched with the multiplex capture of targeted gene regions and analysed by sophisticated bioinformatics tools, enables the simultaneous detection of multiple mutations in multiple genes. With the development of miniaturised technology and benchtop sequencers, it is not unlikely that NGS will soon be adopted for routine molecular diagnostics, including cytological samples. This review addresses (1) the most relevant methodological and technical aspects of the NGS analysis workflow and the diverse platforms available; (2) the issues related to daily practice implementation, namely, the cytological sample requirement and the validation procedures; and (3) the opportunities that NGS offers in different fields of cytopathology, to increase mutation detection sensitivity in paucicellular smears and to extend the analysis to a larger number of gene regions. Cytopathologists involvement and coordination in this rapidly evolving field is crucial for the effective implementation of NGS in the present and future cytological practice.