New Findings for HER2-Positive Breast Cancer
Human epidermal growth factor receptor 2 (HER2) is an important marker in breast cancer. When tumor biopsies are conducted, the tissue is always tested to see if it produces large amounts of HER2. The presence of HER2 indicates that the tumor is very aggressive and grows rapidly, but will likely respond to trastuzumab (Herceptin®). An important SABCS presentation relating to HER2-positive breast cancers is discussed here. NOAH Trial: Using Trastuzumab before Surgery Trastuzumab routinely has been used to treat women with metastatic breast cancer for several years; in the last few years, several trials showed that in combination with chemotherapy, it was very effective in women with early-stage HER2-positive breast cancers (adjuvant treatment). In contrast, using trastuzumab before surgery was investigated in the NeOAdjuvant Herceptin trial (NOAH). Locally advanced breast cancers are aggressive tumors. Although these cancers are located in one breast and have not spread to other parts of the body, they are too large to be removed by surgery. In general, patients with locally advanced breast cancers are treated with chemotherapy before surgery (called neoadjuvant treatment) in an effort to shrink the tumor. If the tumor becomes smaller after chemotherapy, the tumor is surgically removed and patients are then given more chemotherapy after surgery (adjuvant treatment). In the NOAH trial, trastuzumab was added to neoadjuvant chemotherapy for patients with HER2-positive locally advanced breast cancers. After more than half the patients were followed for at least three years, investigators reported almost twice as many patients showed a complete response to treatment (that is, the tumor was completely eradicated) when 14 Spring 2009 Volume 118 News From SABCS 2008 trastuzumab was added to chemotherapy. There were fewer negative events (defined as growth of the tumor, relapse or death) in the trastuzumab group. Patients also appeared to live longer after neoadjuvant treatment; however, this observation may result from chance. Trastuzumab,when given with certain chemotherapy agents called anthracyclines,can make the heart weaker.Because anthracyclines were included in chemotherapy regimens in this trial,investigators carefully followed the heart function of all patients and reported no major heart-related side effects in this trial. Based on these results, the authors concluded that all patients with HER2-positive locally advanced breast cancer should be given trastuzumab along with chemotherapy before surgery. Chemotherapy after Surgery Is Recommended for All HER2-Positive Tumors In current clinical practice, patients who have small tumors or low-grade tumors (consisting of cells that do not divide rapidly) are considered at low risk for relapse. After surgery, these patients are frequently not given chemotherapy. Two studies presented at SABCS looked at the number of patients who relapsed after their breast tumor was removed. One study looked at patients with small tumors who are not generally considered candidates for adjuvant therapy. The second study looked at patients with low-grade tumors that were considered candidates for adjuvant treatment. Both studies showed that patients whose tumors were HER2-negative lived longer than patients whose tumors were HER2-positive. Based on these findings, the authors of both studies suggest that patients with small or lowgrade HER2-positive tumors should be considered high risk and they should be considered candidates for adjuvant chemotherapy or hormonal therapy.
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