Genomic Testing for Breast Cancer
Genomic testing for breast cancer involves analysis of a cancerous tumor sample to evaluate the activity and interaction of specific types of genes the body has and how they affect the behavior of the breast cancer, including how likely it is to grow and spread. Genomic testing is beneficial in that it allows physicians to have a better understanding of the patient’s specific breast cancer case and to help make decisions about whether more treatment after surgery would be beneficial. Genomic testing also allows physicians to offer personalized treatment options that are specific to each case based on the genomic test results.
Genomic Tests Available for Breast Cancer
There are several tests that are currently used for breast cancer patients to analyze genes to predict whether the breast cancer will recur. All the tests can be performed by utilizing a sample of the tissue that was removed during the surgical resection of the tumor or from the biopsy.
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 the likelihood of her benefitting from treatment, such as chemotherapy, after surgery. A recurrence score between 0 and 100 is calculated after the Oncotype DX test analyzes the activity of 21 genes. A higher score increases the risk of recurrence of invasive breast cancer.
The Oncotype DX DCIS (ductal carcinoma in situ) test also estimates the recurrence risk of DCIS as well as the risk of a new invasive cancer developing in the same breast by analyzing the activity of 12 different genes.
Another test is the Breast Cancer Index which has two purposes. First, it helps determine the risk of node-negative, hormone receptor positive breast cancer recurring 5 to 10 years after diagnosis by analyzing the activity of 7 genes. Second, it assists with determining the likelihood of a woman benefiting from taking hormonal therapy for an extended time of 10 years.
The EndoPredict test is another option that helps to predict the risk of distant recurrence of early-stage, hormone receptor positive, HER2-negative breast cancer that is either node-negative or has up to three positive lymph nodes by analyzing the activity of 12 genes. The test then combines the risk score with the tumor size and nodal status. The score labels the cancer as either high risk or low risk of recurrence.
MammaPrint is another test that calculates high risk or low risk of recurrence by analyzing the activity of 70 genes. The results of the test can then be utilized in making treatment decisions.
The Prosigna Breast Cancer Prognostic Gene Signature Assay also calculates the risk of recurrence as high, intermediate, or low by analyzing the activity of 58 genes. This test is used more frequently to predict the risk of distant recurrence.
Genomic testing is providing new possibilities in oncology for therapies and treatment options as well as new diagnostic strategies.
When choosing the most appropriate treatment plan for each individual patient, it is important to consider the score of the test in combination with the following:
- Tumor size and staging
- Protein levels of hormone receptors
- Location of the tumor