A genomic test (also called a genomic assay or a gene expression profile test) 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 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 very small study suggests that women diagnosed with early-stage breast cancer consider genomic test results very important when deciding whether to have chemotherapy, but many of them don’t fully understand what the test results mean.
The research was published in the January 2014 issue of Current Oncology. Read “Patients’ perceptions of gene expression profiling in breast cancer treatment decisions.”
Currently there are three genomic tests used to analyze breast cancer genes to predict recurrence:
- Oncotype DX test
- MammaPrint test
- Mammostrat test
While all three tests are somewhat similar, there are differences:
- The Oncotype DX test is used to estimate a woman’s risk of recurrence of early-stage, hormone-receptor-positive breast cancer, as well as how likely she is to benefit from chemotherapy after breast cancer surgery. The Oncotype DX test also is used to estimate a woman’s recurrence risk of DCIS (ductal carcinoma in situ) and/or the risk of a new invasive cancer developing in the same breast, as well as how likely she is to benefit from radiation therapy after DCIS surgery. The Oncotype DX test analyzes the activity of 21 genes and then calculates a recurrence score number between 0 and 100; the higher the score, the greater the risk of recurrence.
- The MammaPrint test is used to estimate a woman’s recurrence risk for early-stage breast cancer. The breast cancer can be hormone-receptor-positive or hormone-receptor-negative. The MammaPrint test analyzes 70 genes to see how active they are and then calculates either a high-risk or a low-risk recurrence score. MammaPrint results can help a woman and her doctor make a more informed decision about whether to use chemotherapy to reduce recurrence risk.
- The Mammostrat test is used to estimate a woman’s risk of recurrence of early-stage, hormone-receptor-positive breast cancer. The Mammostrat test measures the levels of five genes in breast cancer cells. These measurements are used to calculate a risk index score. The higher the risk index, the more likely the cancer is to come back. Women are assigned to a risk category (high, moderate, or low) based on their risk index score.
Genomic test results, when considered with other features of the breast cancer, can help you and your doctor make a more informed decision about whether to use chemotherapy or other treatments to reduce the risk of recurrence.
This study involved 28 women who had been diagnosed with early-stage breast cancer (stage I or stage II) and had genomic testing. To learn what the women thought about the genomic testing, the researchers interviewed 24 of the women and conducted a focus group with the other four women.
The researchers asked the women about:
- how the genomic test results were used in the treatment decision-making process
- their attitudes toward and understanding of the test results
- other factors that affected the treatment decision-making process
The researchers found that the women understood that the genomic test would suggest whether they would benefit from chemotherapy. Still, many of the women thought that the test results were more scientifically valid, more personalized, and more emotionally significant than other information they had been given about breast cancer.
In reality, genomic test results are based on larger population statistics and are not more personalized than other test results. Genomic test results are one of many factors that women and their doctors use to make treatment decisions. Other factors include:
- your age
- your menopausal status
- the size of the cancer
- hormone-receptor protein levels
- cancer grade
- HER2 status
- your personal preferences
Armed with the best information possible, you and your doctor can decide on a treatment plan that makes the most sense for you and your unique situation.
Editor's note: Since this research was published, new genomic tests have come to market. For the most up-to-date information, visit the Breastcancer.org Breast Cancer Tests page.