Single-Gene Tests: Local Search
Single-gene tests focus on a specific location in a patient's genome. Using this approach, scientists have looked for single genes linked to cancer. This research has revealed some important discoveries such as gene changes called mutations located within the BRCA1 or BRCA2 genes that may confer a significantly increased risk of breast and ovarian cancer. And some single-gene tests continue to inform treatment decisions. For example, colon cancer patients may be tested for a K-ras mutation, or breast cancer patients for HER2 gene activity, before treatment is planned.
A geographical analogy helps depict the scale of the search involved in single-gene tests.