Massively parallel DNA sequencing from routinely processed cytological smears

BACKGROUND Data generated by next-generation sequencing technologies have a pivotal role in precision medicine. These high-throughput techniques are preferentially performed on fresh tissue, but there is an increasing need for protocols adapted to materials derived from formalin-fixed, paraffin-embedded tissue and cytology specimens. METHODS The aim of this work was to show that cytological material collected from archival smears processed for routine diagnoses could be used for massively parallel sequencing and array-based genomic analysis for further studies. RESULTS As a proof of concept, data obtained from May-Grünwald Giemsa- and Diff-Quik-stained archival smears were shown to be in keeping with those obtained from matched frozen controls. CONCLUSIONS The quality of DNA extracted from routinely processed smears is compatible with the multitargeted sequencing of a large series of genes of interest with methods such as array-based genomic analysis and whole-exome sequencing.