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Understanding Cancer Series

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  • Posted: 10/20/2009

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Slide 1

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Single-Gene Tests: Local Search

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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.

Graphic shows a globe and a continent and a country and a U.S., all appear left to right in order of their decreasing size. Below this row appears a cell , a chromosome, a gene, and then a few chemical bases, also in order of decreasing size. Next a magnifying glass shows that a single gene test is like looking at only the smallest end of the scale, the chemical bases.