Massive parallel sequencing of solid tumours - challenges and opportunities for pathologists

The role of pathologists is to provide diagnostic, prognostic and predictive data to enable clinical colleagues to manage patients optimally. Current histo/anatomical pathology is predominantly morphology-based, with the addition of biomarkers, applied largely through immunohistochemistry, fluorescence in-situ hybridization (FISH) and a limited range of polymerase chain reaction (PCR)-based molecular tests. The desire to apply genomics to the clinical care of patients has been facilitated by the human genome project and subsequently by high-throughput technologies known collectively as massive parallel sequencing (MPS, also referred to as next-generation sequencing, NGS). The use of MPS to identify mutations/variants and tissue RNA expression profiles for diagnosis, prognostication and targeted therapy stratification is now a reality in many clinical specialities. If histopathologists are considered experts in solid tumour pathology, MPS potentially falls within their scope; however, it challenges our predominant morphology-based paradigm. This review summarizes and comments on the current and future state of play of MPS for the practising histopathologist. It will focus on somatic mutations in solid tumours and will challenge histopathologists to take further leadership roles in this area.