Cancer Evolution – It’s in the Blood!

In the first of our guest blog posts, Dr. Marco Gerlinger highlights some of the remarkable developments being made in ctDNA analysis, a powerful new technology with the potential to transform tumour predictions and treatment outcomes.

Photo credit: Csutkaa via / CC BY-NC-SA

Photo credit: Csutkaa via / CC BY-NC-SA

Cancer cells are masters in adapting to changing environments. This allows them to colonise other organs, to form metastases and also to acquire drug resistance. Darwinian evolution is thought to be a key driver of this adaptability. Randomly acquired mutations encode for novel phenotypes and some of these phenotypes may allow individual cells to survive changes in the environment1.

This adaptability is a key reason for the high rates of mortality from metastatic cancers. Treating a cancer that cannot evolve would probably be an easy task – maybe as straightforward as eradicating a bacterial infection with antibiotics. Thus, there is great need to understand how and why cancers readily evolve and to use this information to design more effective treatment approaches for ever-changing cancers.
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Predicting evolutionary futures

Photo credit: Living in Monrovia / / CC BY-SA

Photo credit: Living in Monrovia / / CC BY-SA

One of the striking achievements of cancer genomics and its allied bioinformatics has been to construct phylogenetic trees depicting the trajectories of sub-clones in cancers and their ancestral relationships. It’s like taking a peek back in time at the origin and prior evolutionary history of the malignancy.

But what about the converse? Is it possible to infer, from features of cancer cells, what their future potential or ability to evolve into more malignant, metastatic or drug-resistant phenotypes may be? There’s no doubt this would be extremely useful, particularly in the context of early diagnosis and intervention.

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‘Drivers’ and ‘Passengers’: who’s in charge?

Genome sequencing has revealed that a plethora of gene mutations can co-exist in individual cancers: thousands in some cases 1,2. Based on Darwinian theory, we assume that whilst most are irrelevant, buried in the background is a modest number of mutations (perhaps counted in single figures) that are functionally active in a way that contributes to cancer clonal development. The ‘offspring’ of the cells with these mutations will be more successful than the cells that surround them. Continue reading

NCRI 2015 – Evolutionary tales in leukaemia

NCRI 2015

At the 2015 NCRI Conference Professor Mel Greaves, our founding author, was given the Lifetime Achievement Award by CRUK

This post is a synopsis of the lecture I gave at the National Cancer Research Institute (NCRI) conference in Liverpool on the 2nd November 2015 – minus some anecdotes about mentors and colleagues – you needed to be there to hear those. It’s my personal, historical narrative of tackling the challenge involved in unravelling the biology and causes of childhood leukaemia. Continue reading

How many mutations does it take?

For some time before we had the benefit of cancer genomics, it was generally believed that for a cancer to disseminate and become potentially lethal, it would have had to accrue several mutations that, collectively, would provide a kind of ‘full house’ for malignancy.

It was further assumed that, in the absence of rampant genetic instability, the critical set of mutations would arise one at a time and that it would, therefore, take time to assemble a ‘full house’ set. The linear relationship of cancer incidence to age (in log-log plots) was taken to indicate that four to six rate-limiting mutational events might be involved 1,2. However this inference rested on some questionable biological assumptions 3. Continue reading

Background: Darwin’s branching tree of evolutionary phylogeny

Transmutation notebook B

Charles Darwin’s Transmutation notebook B, 1837

Since the turn of this century, cancer genomics has strongly endorsed the Darwinian view of cancer biology 1,2. Interrogation of the genomes of single cancer cells and multi-regional small biopsies of tumours have allowed us to construct evolutionary histories, or phylogenies, of cancer clones – revealing genetic and cellular architectures very reminiscent of Darwin’s iconic drawing of evolution or speciation 2. Continue reading

Background: What has evolution got to do with cancer?

Charles Darwin by Ernest Edwards albumen print, 1865-1866 NPG x1500 © National Portrait Gallery, London

Charles Darwin
by Ernest Edwards
albumen print, 1865-1866
NPG x1500
© National Portrait Gallery, London

‘No man, even under torture, can say exactly what a tumour is.’
J. Ewing, 1916

What exactly is cancer? Can we capture its biological essence in a few words or a phrase? For the ancient Greeks, it was a manifestation of black bile, or constitutional melancholy. The common understanding today is that it reflects renegade, mutant cells proliferating out of control, with a potentially lethal consequence: a territorial hijack of essential, normal tissue functions. Continue reading

Time for a new perspective on cancer?

Charles Darwin by Julia Margaret Cameron albumen print, 1868 NPG P8 © National Portrait Gallery, London

Charles Darwin
by Julia Margaret Cameron, albumen print, 1868, NPG P8
© National Portrait Gallery, London

Evolution by natural selection is the foundation law of biology. So we shouldn’t be surprised that it has great relevance to cancer.

‘Nothing in biology makes sense except in the light of evolution’
Theodosius Dobzhansky, 1973

Almost 40 years ago, Peter Nowell first championed the idea that cancer is, fundamentally, a process of somatic cell evolution 1. Since then, the concept has been validated and elaborated, such that the striking parallels with Darwinian speciation by natural selection in ecosystems have been highlighted on many occasions 2,3,4. Continue reading