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Luck, not lifestyle, may be to blame for more cancers than previously thought

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  • HARI SREENIVASAN:

    Next: the role of chance, what we might call bad luck, in who gets cancer.

    Jeffrey Brown has our look.

  • JEFFREY BROWN:

    According to a new study from the Johns Hopkins University School of Medicine published today in the journal "Science," more cases of cancer than have commonly been thought can be primarily explained by random DNA mutations that occur during cell division, rather than by heredity, lifestyle choices, or environmental influences.

    The study looked at 31 types of cancer, including leukemia, bone, testicular, ovarian and pancreatic cancers. Breast and prostate cancers were not included in the study.

    Cristian Tomasetti is one of the authors of the report and a biomathematician at Johns Hopkins. He joins me now from Baltimore.

    Well, thank you for joining us.

    It seems important, first, perhaps, to explain what you were looking at. What does bad luck or chance mean when it comes to getting cancer?

    CRISTIAN TOMASETTI, Johns Hopkins University School of Medicine: Yes, what it means is that every time a cell, in particular a stem cell, the lonely stem cells, every time it divides, a random mutation can occur and can hit the DNA of this cell.

    And if that mutation happens to be in a gene that is the key regulator and known to be associated with cancer, so let's say a bad mutation, that may lead us to cancer. So that's what we meant for bad luck.

  • JEFFREY BROWN:

    Well, so were you and other researchers surprised to find that there — that bad luck, in a sense, played such a large role in so many cancers?

  • CRISTIAN TOMASETTI:

    Yes.

    I would say that I think it's been known that luck, together with environmental factors like smoking or sun exposure, as well as inherited factors, are three fundamental — three components. And I think what was surprising and unexpected, in a sense, was how large, how important this component of the bad luck turned out to be.

  • JEFFREY BROWN:

    Well, so, you mention the other — the other causes for cancer.

    You are not saying — we should be real clear about this, right? You're not suggesting that people should change their behavior and do things that we know do cause cancer?

  • CRISTIAN TOMASETTI:

    Right. Thank you for mentioning that.

    That's actually very important. I really hope no one takes, you know, this work as saying that, because that would be completely wrong.

  • JEFFREY BROWN:

    It's also important to say, I think, that different types of cancer are different, right, that some tissues seem to be more prone to this random mutation…

  • CRISTIAN TOMASETTI:

    Correct.

  • JEFFREY BROWN:

    … and some more tied to environmental or hereditary traits?

  • CRISTIAN TOMASETTI:

    Yes.

    In fact, I was going to — that was the next thing I was going to say, which is that when we talk about the two-thirds due to bad luck, this is an analysis done across many, many tissues. But there are very important differences.

    For example, it's undeniable the huge impact that smoking has on lung cancer or that sun exposure has on skin cancer. So, the study doesn't contribute — say anything against what we already know to be important.

  • JEFFREY BROWN:

    Well, so what implications would there be for doctors and future research in all this?

  • CRISTIAN TOMASETTI:

    Yes.

    Probably, the biggest implication is that we need to focus resources even more on ways to detect cancer at early stages, when they are still curable, so early detection, and this in particular in developing new methodologies that enable us to find those cancers at much earlier stages.

  • JEFFREY BROWN:

    All right, Dr. Cristian Tomasetti of Johns Hopkins, thank you so much.

  • CRISTIAN TOMASETTI:

    Thank you.

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