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First Comprehensive Genetic Analysis of Breast Cancer Could Change Treatment

Research published by Nature shows there are four distinct types of breast cancer and that genetic changes occurring as cancer cells spread are vastly different for each type. Judy Woodruff talks to National Cancer Institute’s Dr. Harold Varmus for more on what the research could mean for treatment in the future.

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    Next, new research that's changing our understanding of cancer.

    Scientists say they have found new insights into four genetically distinct types of breast cancer, potentially altering the way doctors one day treat the disease.

    The findings were published yesterday in the journal "Nature" as part of a comprehensive genetic analysis of breast cancer.

    Among other discoveries, researchers say that a rare but deadly form of breast cancer bears a genetic resemblance to the kinds of tumors found in lung and ovarian cancers.

    Doctors also learned that the two most common forms of breast cancer, both of which rely on estrogen to fuel their growth and have been treated similarly in the past, are actually genetically distinct from one another.

    Well, for more on this, I'm joined by Dr. Harold Varmus. He's director of the National Cancer Institute. The institute helped to lead the work as part of a larger project to map genetic changes in cancer.

    Dr. Varmus, thank you for being here.

  • DR. HAROLD VARMUS, National Cancer Institute:

    My pleasure.


    So, tell us what is significant about what you found about these four types of breast cancer.


    Well, these four types have actually been known for some time based on work done nearly a decade ago that was intent on characterizing which genes were off and on in breast cancer types.

    And to the surprise of many, it was possible to form four large groups that most breast cancers could fit into.

    What these studies show — and they are part of a much larger effort that the Cancer Institute and the Human Genome Institute are carrying out on many different types of cancer — is that by using a variety of new techniques to sequence the genome, to count the number of copies of genes, to look at which genes are being read out and which proteins are being made, that we can begin to look at the heterogeneity of these four groups and define certain commonalities within the groups that give us — will give us some insight into which therapies are most appropriate and what kind of new therapies might be envisioned.


    So, is this telling you that the genetic markings are more important than just about any other distinction to these breast cancers?

    I mean, we mentioned…


    Well, in general, all cancers have been traditionally characterized by the way they appear under the microscope and the organs in which they arise.

    But as we learn more and more about cancer of every type, including breast, what we learn is that the drivers of cancer are mainly mutations and changes in chromosome organization or numbers of copies of genes, and that those are the instruments that drive a cancer and therefore become ways of categorizing cancer, ways of designing new therapies that specifically target those changes, and markers for knowing whether or not these cancers will respond to conventional existing therapies.


    So, was this a shocking piece of information?


    It wasn't shocking, no.

    We have been going through many kinds of cancers, and many more are to come within this large study.

    And what we're trying to do is to create a warehouse, a compendium of information. The project is called the Cancer Genome Atlas.

    It's an atlas, a warehouse, a storehouse, a database which everyone is free to look at, because all this information is being made publicly available.

    If you go to our website and look at the Cancer Genome Atlas, you will see the information. You can — all these papers are freely accessible to everyone.

    And the point is that we know that every time we approach a cancer with these technologies and look at many hundreds of individual cancers of a certain traditional grouping, like pancreatic cancer or liver cancer or gastric cancer or breast and other cancers that have been published, that we're going to see interesting patterns.

    Every cancer looks different. Every cancer has similarities to other cancers. And we're trying to milk those differences and similarities to do a better job of predicting how things are going to work out and making new drugs.


    And how will that affect the treatment of these cancers? I mean, do you already know how that might happen, or is that just…


    Well, we have an idea.

    First of all, there is the long-range view that, as we understand exactly what's wrong, we will make targeted therapies that are specific for cancers that have certain kinds of genetic aberrations.

    But even in the more immediate future, it's going to be possible to put together our understanding, our description of the genetic changes in a cancer and the responses to existing therapies. And that's the piece that we still miss.

    And one way in which I believe that patients who have cancer now and are being treated now can make a major contribution to the development of more effective and more accurate treatment, using existing therapies.


    So, this — you're saying this could make a difference in the very near future?


    In the next few years. It is not going to change practice overnight.

    Some of the ideas that are in this paper, the connection you mentioned between some of the genetic changes seen in a certain particularly severe from a breast cancer and ovarian cancer, for example, suggest that those cancers have an instability in their genome that can be addressed with some existing therapies. And those therapies are being tested now in those breast cancer patients.

    But what remains to be figured out is how we get the clinical information together with the genetic information in the kind of database that we can all use to begin to predict who is going to respond to which drugs.


    And why is that as hard as it is? What would make that easier?


    Well, in part because it's hard to get the clinical information into a form that can be put into a database that is interpretable.

    Some of this is a matter of learning how to massage the data so we make the correlations that are truly helpful.

    The second is that we need to overcome a reluctance to provide personal clinical information and genetic information to a database that will help others, to provide the right kinds of consent forms and privacy protections that allow this all to happen.

    And I would urge patients who have cancer now to think of themselves as information donors who can benefit not just others who will have cancer later, but themselves over the next few years.

    Because cancer patients are living longer and better lives, thanks to better symptom control, more effective therapies, and a deeper understanding of cancer that has come about through research over the last decade.


    So, finally, just to broaden this out, what are your hopes, Dr. Varmus, for this larger genetic study of all kinds of cancer?


    Well, I believe that we are going to have a much deeper appreciation of what kinds of abnormalities in cancer cells and in the surrounding cells that feed and respond to cancers are vulnerabilities that will allow us to make better predictions of which kinds of drugs will work to treat these cancers.

    They also become markers that allow or enable early detection. They become signposts for thinking about what the environmental causes of cancer might be and for thinking about how we can prevent cancers more effectively.

    But this is not just all about treatment. And we need to think imaginatively about how we prevent cancers, which is the ultimate goal.


    It must be very exciting for you.


    Well, it's a difficult problem that we think we're making great progress against these days. And it is an affirmation of the importance of medical research to the nation.


    Dr. Harold Varmus, we thank you very much for being here.


    Pleasure. Thanks.