DR-238 Accurate Discrimination of Major Cancer Types via Whole Genome Somatic Mutation Patterns

The two strongest factors predicting a human cancer’s clinical behaviour are the primary tumour’s anatomic organ of origin and its histopathology. However, roughly 3% of the time a cancer presents with metastatic disease and no primary can be determined even after a thorough radiological survey. A related dilemma arises when a radiologically defined mass is sampled by cytology yielding cancerous cells, but the cytologist cannot distinguish between a primary tumour and a metastasis from elsewhere. Here we use whole genome sequencing (WGS) data from the ICGC/TCGA PanCancer Analysis of Whole Genomes (PCAWG) and the Hartwig Medical Foundation to develop a machine learning classifier able to accurately distinguish among ~30 major cancer types using information derived from somatic mutations alone. This demonstrates the feasibility of automated cancer type discrimination based on next-generation sequencing of clinical samples. In addition, this work opens the possibility of determining the origin of tumours detected by the emerging technology of deep sequencing of circulating cell-free DNA in blood plasma.

Lincoln Stein, Ontario Institute for Cancer Research, Canada