There's some really interesting—and rather disturbing—research coming out of the UK on the nature of cancer cells and why advanced-stage cancers are so difficult to treat.
Scientists have long known that the same type of cancer can play out in very different ways, from a genetic perspective, in one patient compared to another. But this new research shows that, even within the same patient—even within the same tumor—different samples of cancer cells have more genetic differences than they have similarities.
That's a very big deal. It means that cancer cells aren't just cells that grow uncontrollably. They also mutate. Which means that they evolve. That fact has serious implications for cancer treatment. Just like bacteria can evolve to become resistant to antibiotics, cancer cells can evolve resistance to the treatments we throw at them. At Not Exactly Rocket Science, Ed Yong explains how this discovery fits into the bigger picture of why curing cancer is so damned difficult:
For a start, cancer isn't a single disease, so we can dispense with the idea of a single "cure". There are over 200 different types, each with their own individual quirks. Even for a single type – say, breast cancer – there can be many different sub-types that demand different treatments. Even within a single subtype, one patient's tumour can be very different from another's. They could both have very different sets of mutated genes, which can affect their prognosis and which drugs they should take.
And now we know that's true within a tumor, as well. At the Cancer Research UK blog (where Ed used to work), Henry Scowcroft has a nice summary of how this one discovery explains three perplexing problems we've long had with cancer cells:
Firstly, cancer is very difficult to cure after it has spread. This is despite years of progress in chemotherapy and radiotherapy, two techniques that can offer respite to people with advanced cancer.
Secondly, most advanced cancers eventually become resistant to every type of drug used to treat them – both 'traditional' chemo and these newer agents. This is quite extraordinary: tumours can work out how to cope with chemicals that they've never 'seen' before – a biological superpower far beyond that of infectious diseases. Just consider how it's taken 'multidrug resistant' bacteria like MRSA decades to evolve. Yet cancers can do this in a matter of months or even weeks. How?
And finally, researchers haven't yet managed to develop tests to predict how a patient's disease will progress, nor monitor their progress (a field called 'biomarker' research) – this is despite years of research, and a lot of tantalising pilot studies. Sometimes researchers detect a promising 'signal' by looking at samples from a handful of patients, only for this to disappear in larger numbers of people.
Read Ed Yong's full story on this research.
Read Henry Snowcroft's full story on this research.