HER2 Levels Drop if HER2-Positive Cancers Respond to Chemo Plus Herceptin Before Surgery

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HER2-positive cancers have too many copies of the HER2/neu gene, which make too much of the HER2 protein. A study found that when HER2-positive breast cancers respond well to chemotherapy and Herceptin (chemical name: trastuzumab) before surgery, HER2 protein levels in the blood drop. These results were reported at the 2010 European Breast Cancer Conference.

Treatment given to weaken and destroy breast cancer before surgery is called neoadjuvant treatment. Neoadjuvant treatment isn't routinely used to treat early-stage breast cancer, but may be used if the cancer is large, aggressive, or advanced-stage. Chemotherapy is typically the neoadjuvant treatment given.

HER2-positive breast cancers tend to be aggressive, so doctors may recommend neoadjuvant treatment for them. Herceptin, a targeted therapy, is not approved by the U.S. Food and Drug Administration to be used before surgery, but doctors sometimes use it that way.

The way a cancer responds to treatment before surgery can affect the type of surgery that is done, as well as other treatments given after surgery. So having a good way to judge how a cancer is responding to treatment before surgery is helpful. This study suggests that measuring HER2 protein levels in the blood before and after neoadjuvant treatment of HER2-positive breast cancers might be a good way to do this.

In this study, 90 women diagnosed with HER2-positive breast cancer and 85 women diagnosed with HER2-negative breast cancer were treated with chemotherapy before surgery. The HER2-positive breast cancers also were treated with Herceptin before surgery. The researchers measured the women's blood levels of HER2 protein before and after the neoadjuvant treatment.

After the women completed the neoadjuvant treatment and had surgery to remove the cancer, the researchers looked at tissue removed during surgery to see how many had a very good response to the neoadjuvant treatment. Researchers use the term "complete pathologic response," which means there were no active cancer cells in the tissue.

All the women had HER2 protein in their blood before adjuvant treatment, but levels were twice as high in women diagnosed with HER2-positive breast cancer compared to women diagnosed with HER2-negative breast cancer.

Two groups of women diagnosed with HER2-positive breast cancer were the most likely to have a complete pathologic response to the neoadjuvant treatment:

  • women who had the highest HER2 protein levels before neoadjuvant treatment
  • women whose HER2 protein levels dropped by 20% or more after neoadjuvant treatment

Based on the results, the researchers believe that measuring the drop in blood HER2 protein levels before and after neoadjuvant chemotherapy and Herceptin may help predict which women are most likely to benefit from Herceptin given before surgery.

More research is needed to better understand how HER2 protein levels in the blood can help plan treatment for HER2-positive breast cancer. Stay tuned to Breastcancer.org for the latest news on research discoveries that may lead to better ways to diagnose and treat breast cancer.

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