Genetic and Other Testing

It is important for you to discuss with your physician the tests necessary to thoroughly define your diagnosis of metastatic breast cancer. Certain tests can determine the type (or subtype) of metastatic breast cancer that you have and any mutations. These are particularly important to determine the best treatment options for you.  You will want to consider some of the following more common tests.

  • Estrogen and Progesterone Receptors: A test to measure the amount of estrogen and progesterone (hormones) receptors in cancer tissue. If there are more estrogen and progesterone receptors than normal, the cancer is called estrogen and/or progesterone receptor positive. This type of breast cancer may grow more quickly. The test results show whether treatment to block estrogen and progesterone may stop the cancer from growing.
  • Human Epidermal Growth Factor Type 2 Receptor Her2/NEU: A laboratory test to measure how many HER2/neu genes there are and how much HER2/neu protein is made in a sample of tissue. If there are more HER2/neu genes or higher levels of HER2/neu protein than normal, the cancer is called HER2/neu positive. This type of breast cancer may grow more quickly and is more likely to spread to other parts of the body. The cancer may be treated with drugs that target the HER2/neu protein, such as trastuzumab and pertuzumab.
  • Multigene tests: Tests in which samples of tissue are studied to look at the activity of many genes at the same time. These tests may help predict whether cancer will spread to other parts of the body or recur (come back).

There are many types of multigene tests. The following multigene tests have been studied in clinical trials:

Oncotype DX

This test helps predict whether early-stage breast cancer that is estrogen receptor positive and node negative will spread to other parts of the body. If the risk that the cancer will spread is high, chemotherapy may be given to lower the risk.


A laboratory test in which the activity of 70 different genes is looked at in the breast cancer tissue of women who have early-stage invasive breast cancer that has not spread to lymph nodes or has spread to 3 or fewer lymph nodes. The activity level of these genes helps predict whether breast cancer will spread to other parts of the body or come back. If the test shows that the risk that the cancer will spread or come back is high, chemotherapy may be given to lower the risk.

Based on these tests, breast cancer is described as one of the following types:

  • Hormone receptor positive (estrogen and/or progesterone receptor positive) or hormone receptor negative (estrogen and/or progesterone receptor negative). ER+/PR+ or ER-/PR-

  • HER2/neu positive or HER2/neu negative.
  • Triple negative (estrogen receptor, progesterone receptor, and HER2/neu negative).

This information helps the doctor decide which treatments will work best for your cancer.

Genetic Testing For Inherited Gene Mutations: 

The National Comprehensive Cancer Network (NCCN) recommends everyone diagnosed with metastatic breast cancer get testing for BRCA1 and BRCA2 gene mutations. These tests are called expanded panel testing or multi-gene testing. Panel tests look at 28-84 genes, depending on the specific test. If you have a BRCA1/2 gene mutation, talk with your health care provider about your options.

There are many advantages to testing including determining how high-risk and moderate-risk gene mutations can help health care providers personalize medical care. Some other gene mutations that can mean increased risk

  • ATM
  • CDH1
  • CHEK2
  • NBN
  • NF1
  • PALB2
  • PTEN
  • TP53

Risk-lowering options for genetic breast cancer

  • Risk lowering drugs (tamoxifen or raloxifene)
  • Prophylactic mastectomy
  • Prophylactic oophorectomy


Other Testing

FoundationOne CDX - is a test for people with any type of advanced cancer. It uses comprehensive genomic profiling (CGP) to search 324 genes for cancer-relevant mutations in the DNA of your tumor. The results of the test may help you and your doctor explore treatment options.

For mutations: PIK3CA is the most commonly mutated gene in HR+/HER2- advanced breast cancer.PIK3CA mutations can be detected in tissue or plasma specimens and are generally stable. Primary or metastatic breast cancer tumor tissue may be tested with the QIAGEN therascreen® PIK3CA RGQ PCR Kit is an FDA-approved companion diagnostic (CDx) test for the detection of 11 mutations in the PIK3CA gene using genomic DNA (gDNA) extracted from formalin-fixed, paraffin-embedded (FFPE) breast tumor tissue or circulating tumor DNA (ctDNA) isolated from K2EDTA anticoagulated peripheral whole blood plasma taken from patients with breast cancer.