MAY 12, 2017 2:29 PM PDT

How Scientists 'Carbon Dated' Colorectal Cancer


By diving deep into the cancer history of one patient, scientists say they’re able to ‘carbon date’ the cancer down to the precise stage level. The technique revealed unique aspects of cancer genomics and the metastatic process - information which could ultimately guide doctors in making more effective diagnostics for their patients.

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"One of the questions patients often ask is how long a cancer has been present before causing symptoms or spreading to other organs,” said Dr. Nicola Valeri, Leader of the Gastrointestinal Cancer Biology and Genomics Team at The Institute of Cancer Research, London, and the study co-leader. "Our study for the first time is able to answer those questions for an individual patient by effectively 'carbon dating' the cancer at different stages in its development.”

To get down to such a level, the team focused on a single case of bowel cancer. While some studies are impressive by the sheer size of patients that were included in the study, the current study is impressive by the incredible depth of information gleaned from just a single patient.

In particular, the case study was unique in that the patient had developed metastatic cancer was attributed to a biopsy needle track. The phenomenon is known as needle tract seeding, and it occurs in the rare case when cancerous tissues form along the needle track where the tissue was sampled.

This information allowed researchers to better pinpoint different stages in the patient’s cancer progression. The needle tract seeding provided a timeline for when the cancer metastasized to the chest wall. Then, using genome sequencing data from primary and metastatic sites, the team could “[infer] the complete chronology of the cancer by exploiting the time of needle tract seeding as an in vivo ‘stopwatch’.”

"We found that in this case the patient's disease advanced much faster than we had expected - within a year of the original tumour forming. If we could provide this kind of information more routinely for patients, it would be extremely valuable in guiding decisions on treatment and follow-up,” said Valeri.

The team postulate, based on the rapid advancement of the metastasis within the first year, that major genetic instabilities were the main drivers behind the cancer’s spread. That is, large chromosomal deletions, duplications, or translocations could be quite accurate predictors of a cancer’s aggressiveness.

"The mathematical techniques we borrowed for our study were originally developed to measure the time when new species of plants and animals arose during evolution. Our research was able not only to track the genetic evolution of the cancer, but also to put precise timings on each stage in a cancer's progression,” said Dr. Andrea Sottoriva, the study co-leader. "Tracking, or even better predicting, a cancer's behaviour will be key to planning new treatment strategies that target tumours with drugs at exactly the right time for maximum effect."

Additional source: Institute of Cancer Research

About the Author
Doctorate (PhD)
I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at
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