Targeted Therapy: The New Frontier in Breast Cancer

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Dr. Max Gomez, CBS News Medical Correspondent, hosted a panel discussion at Memorial Sloan Kettering on how precision medicine has launched a revolution in the treatment of breast cancer and many other types of cancer. Medical oncologists José Baselga, Maura Dickler, and David Hyman participated in the discussion.

The experts explained that cancer occurs when normal cellular processes go awry, often due to genetic mutations that are acquired sometime during a person’s life. “It is not dissimilar from having a very powerful car…that has the gas pedal stuck,” said Dr. Baselga. “That thing is going to continue to go very, very fast until it crashes.” By identifying a genetic mutation and its downstream effects, researchers can stop many cancers in their tracks.

The development of trastuzumab (Herceptin®) — a targeted therapy that blocks a mutated receptor in a highly aggressive type of breast tumor known as HER2-positive breast cancer — illustrated the value of this approach. Before the drug was available, many women with HER2-positive breast cancer survived less than six months. Today, more than 90 percent of women with HER2-positive tumors who are treated with trastuzumab are cured.

Thanks to advances in genomic sequencing, it is easier and faster than ever to identify the specific genetic mutations that lead to cancer in individual tumors — including breast tumors that are dependent on receptors for estrogen, progesterone, and HER2, as well as the so-called “triple negative” tumors that do not rely on any of these receptors. Memorial Sloan Kettering’s Kravis Center for Molecular Oncology currently sequences the genomes of 1,000 tumors each month. Doctors use information from these tests to determine which therapy or combination of therapies may be most effective in treating a particular tumor. In the near future, blood tests may be used to obtain much of the same information, reducing the need for biopsies. They may also be able to apply the principles of precision medicine to intercepting breast cancer before it begins to take hold.