Screening Techniques I will now discuss the technical aspects of genetic screening for breast cancer by presenting the major techniques used, how these techniques differ, and which ones are currently the most promising. Mammography is a procedure offered to the general public base d on gender and age, is relatively inexpensive, and whose main goal is to provide early detection of breast cancer. Genetic screening applies only to high risk individuals, is much more expensive, and whose main goal is only to determine risk of developi ng breast cancer at some point in a woman's lifetime. The discovery of mutations through genetic screening does not guarantee that a woman will ever develop the actual disease. In contrast, a positive mammography indicates that a tumor is already presen t in the body.
Many tumors are already very large by the time they are even detected through a mammogram.
The major obstacle in developing successful screening techniques involves the size and complexity of breast cancer genes. BRCA1 and BRCA2 are both very large genes with many exons and a substantial number of different mutations. It is inconceivabl e that one test could detect every possible mutation. Also complicating the issue is the continuing discovery of additional genes that may be involved in breast cancer susceptibility. The techniques I will discuss here pertain only to BRCA1 and BRCA2, b ecause researchers have the most knowledge about these particular genes.