A genomic test (also called a genomic assay) analyzes the activity of a group of genes linked to the risk of a particular disease. The tests are done on blood or tissue samples. For example, a genomic test may help figure out if a woman diagnosed with early-stage, hormone-receptor-positive breast cancer has a high, medium, or low risk of recurrence (the cancer coming back), as well as if she's likely to benefit from chemotherapy to reduce that risk.
A study found that an experimental genomic test on a group of genes linked to the risk of hormone-receptor-positive breast cancer may be able to help predict risk. Still, it's not clear how useful the test is. The test is also expensive.
In the Million Women Study, researchers used the test to look at differences in the activity of 14 genes (called single-nucleotide polymorphisms or SNPs) in more than 10,000 women diagnosed with breast cancer and more than 10,000 women not diagnosed with breast cancer. Test results were reported as breast cancer risk scores based on the activity of the 14 SNPs in each woman.
The researchers wanted to see how closely the risk scores were linked to actual breast cancer diagnoses:
- The women with the highest risk scores (the highest 20%) were twice as likely to be diagnosed with breast cancer compared to women with the lowest risk scores (the lowest 20%).
- The genomic test was most useful in predicting the risk of hormone-receptor-positive breast cancer. The test wasn't useful in predicting the risk of hormone-receptor-negative breast cancer.
Because the genomic test risk scores were only weakly linked to actual breast cancer risk, the researchers concluded the experimental test doesn't offer much value compared to assessing risk based on family and personal health history.
Doctors are continuing to look for better ways to figure out each woman's individual risk of breast cancer. The goal is to create a personalized screening and breast health plan tailored to that risk. In the meantime, it's a good idea to do all you can to reduce your risk of breast cancer. You can learn about some steps you can take to keep your risk as low as it can be in the Breastcancer.org Lower Your Risk section.