Dr. Larry Norton on 35 Years of Breast Cancer
This October, SHARE recognizes both Breast Cancer Awareness Month and 35 years of supporting women affected by breast cancer. In honor of these dual commemorations, we interviewed Dr. Larry Norton, Deputy Physician-in-Chief for Breast Cancer Programs at Memorial Sloan-Kettering, about how breast cancer treatment has changed in the past 35 years.
SHARE: What have been the major changes in thinking about breast cancer over the past 35 years?
Dr. Norton: Thirty-five years is a very long time! There have been so many changes that many volumes of textbooks have been written about them. But it is fair to say that the major shift has been that our understanding of the biology of breast cancer has undergone a revolution commensurate with the overall explosion of information that started with the discovery of the structure of DNA. Thirty-five years ago we thought of breast cancer as a disease exclusively of unregulated cell division, with the pressure of too many cells in the lump forcing some of them into lymphatic channels that flowed into the lymph nodes in the armpit. We thought that if they broke through that filter they could then gain access to the body's bloodstream and that this was the origin of metastases.
We now understand that the reason cancer cells spread is not because of mechanical pressures but because they have abnormal molecules (or normal molecules in abnormal abundance), the products of abnormal DNA, that allow the cells to grow in parts of the body where they do not belong. By assessing these proteins -- including the estrogen receptor, the progesterone receptor, and HER2 -- we can tell a lot about how the cells misbehave and the best way to kill them.
Another consequence of improved understanding is that we hypothesized that lumpectomy and radiation therapy could be just as good a treatment as mastectomy, and for many women this turned out to be true. In the past, if any lymph nodes under the arm were found to have cancer cells we routinely removed them all. But recently we have discovered that most patients who have only one or two cancer-containing lymph nodes do not need further surgery.
SHARE: What's available (e.g., treatments, approaches, etc.) now that didn't used to be available and how have these innovations changed people's lives?
Dr. Norton: When I started as a breast oncologist all women with breast cancer had mastectomies and full axillary dissections, and some were still having radical mastectomies, which removed muscles and much more tissue than simply removing the breast. I remember breast cancer therapy before we had drugs like tamoxifen (and much later the aromatase inhibitors) that prevent estrogen from stimulating the growth of cancers containing estrogen receptors. Our chemotherapy (a poor term: a better term would be "drugs that kill dividing cells") was very toxic, very prolonged, and much less effective than what we have now. We also now have very effective medicines to prevent or manage the side-effects of chemotherapy, like nausea and low white blood cell counts, which we didn't have just a few years ago. Hence, modern breast cancer therapy is generally less mutilating, easier to tolerate, and more effective than in the past.
We also have better means of diagnosis: Better mammograms, MRIs when we need then, better ultrasonography to evaluate possible cysts, etc. This means that we can diagnose cancers at much smaller sizes, leading to less noxious treatments and higher cure rates. And we are starting to make strides in cancer prevention, particularly using the anti-hormone drugs that are also effective as therapies.
SHARE: Where do the greatest challenges in the field lie?
Dr. Norton: The greatest challenge we face is to keep the momentum going at a time of drastically reduced budgets. We have more scientific leads than ever before: A better understanding of the immune system and its complex relationship to cancer, a better understanding of the genes (pieces of DNA) that go wrong in cancer, a better appreciation of the role of new blood vessels and white blood cells that make cancers viable, and many other fascinating topics. This is not a time in history to slow down our efforts, just when the finishing line is in sight!
Want to hear Dr. Norton speak in person? Learn more
Posted September 30, 2011.
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