Researchers at UHN have recently drawn a molecular portrait that provides the first complete picture of localized, multi-focal prostate cancer—a disease in which multiple tumours develop within the prostate. This exciting study also unveils a new gene subgroup driving this tumour development.
The study, led by PM Senior Scientist Dr. Robert Bristow, involved the molecular profiling of 74 patients with Gleason Score 7 index tumours—this is the classification system used to evaluate aggressiveness in prostate tumours. Of these, whole-genome sequencing was done on 23 multiple tumour specimens from five patients whose prostates were removed at surgery. By analyzing the genetics of the different cancers within each prostate, "aggression scores" were assigned to each cancer, which revealed that even small cancers can contain aggressive cells capable of altering a patient's prognosis. Moreover, detailed analysis showed that two members of the MYC cancer gene family were at play in development of the disease and one of them, C-MYC, was the culprit in driving aggressive disease.
Dr. Bristow says that about half of all prostate cancer patients either have C-MYC or L-MYC mutations, but never both. "Our findings suggest that we are getting closer to subtyping the cancer based on which gene is present to determine a patients' disease aggression in terms of the risk of spread outside the prostate gland at time of treatment. Using this data we aim to develop a clinical test within the next three years that is capable of informing doctors and patients about specialized treatments for each prostate cancer patient."
This work was supported by the Movember Foundation through Prostate Cancer Canada, the Ontario Institute for Cancer Research, the Government of Ontario and The Princess Margaret Cancer Foundation.
Spatial genomic heterogeneity within localized, multifocal prostate cancer. Boutros PC et al. Nature Genetics. 2015 May 25. [Pubmed abstract]