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Tumor markers are proteins found in blood or urine when cancer is present. Although they are not used to diagnose cancer, the presence of certain markers can help predict how aggressive a patient’s cancer may be and how well the cancer may respond to certain types of drugs.
Tumor markers relevant for breast cancer prognosis include:
HER2. The American Cancer Society recommends that all women newly diagnosed with breast cancer get a biopsy test for a growth-promoting protein called HER2/neu. HER2-positive cancer usually occurs in younger women and is more quickly-growing and aggressive than other types of breast cancer. The HER2 marker is present in about 20% of cases of invasive breast cancer. Two types of tests are used to detect HER2:
- Immunohistochemistry (IHC)
- Fluorescence in-situ hybridization (FISH)
Either test may be used as long as it is performed by an accredited laboratory. Tests that are not clearly positive or negative should be repeated.
Treatment with trastuzumab (Herceptin) or lapatinib (Tykerb) may help women who test positive for HER2. In 2008, the FDA approved a new genetic test (Spot-Light) that can help determine which patients with HER2-positive breast cancer may be good candidates for trastuzumab treatment.
Other Markers. Other markers that may be evaluated include CA 15-3, CA 27.29, CEA, ER, PgR, uPA, and PAI-1.
Gene Expression Profiling
Gene expression profiling tests (Oncotype DX, MammaPrint) examine a set of genes in tumor tissue to determine the likelihood of breast cancer recurrence. These tests are also used to help determine whether adjuvant (following surgery) drug treatments should be given. The American Society of Clinical Oncology and the National Comprehensive Cancer Network recommend that gene expression profiling tests be administered to newly diagnosed patients with node-negative, estrogen-receptor-positive breast cancer (only Oncotype DX is approved for this use). Based on the results, a doctor can decide whether a patient who has had surgery may benefit from chemotherapy.
Other Factors for Predicting Outlook
Tumor Size and Shape. Large tumors pose a higher risk than small tumors. Undifferentiated tumors, which have indistinct margins, are more dangerous than those with well-defined margins.
Rate of Cell Division. The more rapidly a tumor grows, the more dangerous it is. Several tests measure aspects of cancer cell division and may eventually prove to predict the disease. For example, the mitotic index (MI) is a measurement of the rate at which cells divide. The higher the MI, the more aggressive the cancer. Other tests measure cells at a certain phase of their division.
Effect of Emotions and Psychological Support
Recent evidence has not supported early reports of survival benefits for women with metastatic breast cancer who engage in support groups. However, some studies have suggested that psychotherapy, group support, or both may relieve pain and reduce stress, particularly in women who are suffering emotionally.
Stress has been ruled out as a risk factor either for breast cancer itself or for its recurrence.
Review Date: 11/08/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine,
Harvard Medical School; Physician, Massachusetts General Hospital.
Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M.,
Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
