There are many ways to stand out in a crowd—one way is to look different from those around you.

As cancer progresses, tumour cells develop a number of changes in their DNA that enable them to be more easily detected. One particular type of change to DNA is known as an epigenetic change. Rather than changing the genetic code, epigenetic modifications control how the code is read.

“A major challenge in treating cancer is detecting it early. Finding rare cancer-specific mutations in the blood, especially at earlier stages is difficult,” says Dr. Daniel De Carvalho. “Epigenetic changes, which do not alter the underlying DNA sequence, are not similarly constrained and could provide a new way to detect cancer.”

Dr. De Carvalho and his team took advantage of this phenomenon to develop a blood test that can detect and classify cancer at its earliest stages.

His team profiled thousands of epigenetic changes in multiple cancer types and used the data to predict the presence of cancer DNA in the blood.

They found that epigenetic changes in blood DNA could be used to accurately detect and classify tumours. They have since expanded this research and successfully matched more than 700 tumour and blood samples for a variety of cancer types.

Next steps include testing this method in large studies where blood samples are collected months to years before cancer diagnosis. These studies will help to determine whether the test can be used in the clinic to screen for cancer.

OF FLOWERS AND CANCERS

In nature, the colours that are displayed on flowers’ petals provide an example of epigenetics in action. Despite having the same DNA, epigenetic changes explain why one species of flower can display a variety of different petal colours. Similarly for cancer, epigenetic changes contribute to the  characteristics that differentiate tumour cells from normal cells.

In this study, the researchers looked at a particular type of epigenetic modification called methylation. This alteration includes the addition of tiny chemical structures to DNA that turn genes on and off. By uncovering a new way to profile methylation patterns in blood DNA that are unique to cancer cells, these results reveal a new way to detect cancer. One day, using this technology, individuals may be screened for the earliest stages of cancer using a simple, non-invasive and convenient blood test.

Shen SY, et al. Nature. 2018 Nov;563(7732):579-583. Supported by the University of Toronto’s McLaughlin Centre, the Canadian Institutes of Health Research, Canadian Cancer Society, Ontario Institute for Cancer Research, and The Princess Margaret Cancer Foundation. D De Carvalho holds a Tier 2 Canada Research Chair (CRC) in Cancer Epigenetics and Epigenetic Therapy. T Pugh holds a Tier 2 CRC in Translational Genomics.