Breast cancer is the most common cancer among women and the second leading cause of cancer death among American women. In 2009, approximately 194,280 patients are estimated to be diagnosed with invasive breast cancer and 62,280 with carcinoma in situ. An estimated 40,610 will die from the disease. For a medium-risk women, the incidence of breast cancer is one in eight.
Tumor markers in breast cancer used in the clinic include CA 15-3, CEA (carcinoembyonic antigen) and CA 27-29. All have a low sensitivity and specificity, and therefore are not useful in detecting early breast cancer. CA 15-3 levels are increased by approximately 5-30% of patients in Phase 1 of the disease, 15-50% with step 2, 60-70% of stage 3 and 65-90% Stage 4. CA 15-3 measurements were also elevated in 15-20% of women with benign breast conditions, 50-60% with liver disease, lung cancer 20-70%, 15-60% of gastrointestinal and colorectal cancer , and 40-60% of cases of ovarian cancer. CEA is more common in colorectal cancer, 27-29 whereas CA is more specific for breast cancer. These three tumor markers have not been validated for monitoring treatment in patients with advanced, especially if the cancer can be assessed with conventional techniques. The American Society of Clinical Oncology recommends the use of CEA, CA 15-3 and CA 27-29 in only one metastasis, while the European Group on Tumor Markers recommended for use in disease surveillance in general.
With current technology, circulating tumor cells were found in very rare cases of early breast cancer. Circulating tumor cells detected and identified in two patients with metastatic breast cancer is associated with worse outcomes. Circulating tumor cells can also predict response to treatment.
There is much research underway to investigate new biomarkers for early detection of breast cancer. Based markers include blood cells, DNA, RNA, peptides, sugars and autoantibodies. Breast-based markers as nipple breast ductal fluid and fine needle aspiration (FNA) are also the cells, DNA, RNA, proteins, sugars, and autoantibodies.
In the future it is likely that a combined approach to simultaneously measure multiple markers would be more successful in detecting early breast cancer. Ideally, a panel of biomarkers should be able to detect breast cancer in asymptomatic patients, and improve the accuracy of mammography. A reliable biomarker signature May serve as news of breast cancer, even in normal mammograms and physical examination, and would also indicate more intensive diagnostic evaluation and / or preventive treatment.