National Research Council. "5 Biologically-Based Technologies." Saving Women's Lives: Strategies for Improving Breast Cancer Detection and Diagnosis. Washington, DC: The National Academies Press, 2005. 1. Print.
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Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis
New technologies should be developed in conjunction with experts in the current best practices for breast cancer detection and diagnosis.
Novel diagnostic approaches need to be validated in large-scale clinical studies.
CLUES TO BREAST CANCER: INDIVIDUAL BIOMARKERS
Broadly defined, a biomarker is an objectively measurable characteristic that can be evaluated as an indicator of normal biological processes, disease, or response to therapeutic intervention.15,65 The search for biomarkers of breast cancer should not be confused with the search for inherited, or germ-line, mutations that affect the likelihood of developing breast cancer. Although the discovery of such mutations is important to assess breast cancer risk and may, ultimately, lead to the identification of the causes of breast cancer, the presence of such mutations does not indicate or predict the presence of breast cancer in an individual.
Biomarkers are being sought—and some have been identified—across a wide spectrum of events in the development of breast cancer, as shown in Table 5-1. The clinical use of breast cancer biomarkers is currently limited largely to prognosis, predicting response to therapy, and monitoring patients with diagnosed malignancy, but biomarkers hold considerable potential for risk assessment, screening, diagnosis, and the identification of therapeutic targets.11,18,38,44,55,58,65 Fulfilling that potential will not be easy. There are considerable biological and technical challenges to both the discovery and development of assays to detect early events in cancer development.18,44,55
The search for cancer biomarkers is proceeding along parallel paths: the “hypothesis-driven” assessment of candidate genes or proteins and the “discovery-based” comparison of gene expression and proteomic profiles.55,58 The potential uses and limitations of bioassays based on individual biomarkers for breast cancer are reviewed in this chapter. Molecular profiles of breast cancer, as revealed by DNA microarrays and proteomic analysis, are also discussed later in this chapter.
Biomarker Assays May Complement Mammography
Research on cancer detection has long been inspired by the search for a single, specific biomarker: a molecule or compound produced at such high levels by newly malignant or premalignant cells that it could be detected in an easily obtained fluid or tissue sample. This ideal marker would appear in all patients with a specific type of cancer and be absent or below a definable threshold in individuals without the disease. Its concentration in the sampled
