Cancer early detection and classification using methylome analysis of cell-free DNA

Principal Investigator: Dr. Philip Awadalla

Affiliation: Ontario Institute for Cancer Research

Start Year: 2021

Cancers are a leading cause of death globally. For common cancers, such as lung cancer, patients diagnosed early have a 70% five-year survival rate, while those diagnosed at later stages have one and five percent five-year survival. The development of an approach for early detection could significantly improve patient survival. Examining fragments of DNA that have been released from cells (cell-free DNA (cfDNA)) in the blood provides an opportunity for non-invasive diagnostic approaches, as DNA released from tumoural and healthy cells can be distinguished from one another. Current biomarker studies assess the genomics of blood samples collected from cancer patients, however detecting cancer at its earliest stages, requires profiling of blood prior to diagnosis. In CanPath, we will identify individuals who developed lung or pancreatic cancer following recruitment and blood sample collection to identify early biomarkers of disease. We will isolate cfDNA from plasma, and profile methylation patterns: a modification of DNA that informs the specific tissue cfDNA is released from. To characterize cancer-specific markers, we will compare pre-cancer blood profiles to matched controls (who have never been diagnosed with cancer). We will identify cfDNA fragments that are uniquely methylated in pre-cancer blood to develop cancer-specific cfDNA markers. Our investigation using pre-cancer plasma from the Ontario Health Study revealed signatures of cancers up to six years before breast, pancreatic or prostate cancer diagnosis. Due to the low incidence of pancreatic cancers, additional samples are required to validate our ability to predict pancreatic cancer and investigate our predictive potential for lung cancer.