What Is Prostate Cancer Genomic Testing?
Genomic testing has become an important part of customizing prostate cancer treatment. It can help men with high-risk prostate cancer have a more effective treatment so they can reduce their risk of dying of prostate cancer.
Genomic testing looks at your overall DNA, and genes just in the cancer tissue. This is done to learn more about the cancer. It may help your doctor understand how fast-growing (aggressive) the cancer is. This can help them decide which treatments are more likely to work.
There are two types of genomic testing:
- Germline testing. This looks at the genes you were born with. These genes are found in almost every cell in your body and are inherited from your parents.
- Somatic testing. This looks at genetic changes that are just in the cancer cells.
These tests can give different types of information, so your doctor may recommend one or both.
Genomic testing is a type of biomarker testing for prostate cancer. You can learn more about biomarker testing in Understanding Prostate Cancer Biomarker Testing.
What Does Genomic Testing Tell My Doctor?
Genomic testing can help your doctor better understand the nature of your prostate cancer. Depending on the type of test, it may give information that helps answer questions such as:
- How fast-growing (aggressive) is the cancer likely to be?
- Is the cancer more likely to spread?
- How likely is the cancer to come back after treatment?
- Are there treatments that may work well for this cancer?
Genomic testing is just one tool that a doctor can use. The results are considered along with other information, such as your PSA level, biopsy results, cancer stage, overall health, and previous treatments.
Understanding Germline Testing
Germline testing looks for genetic changes that you were born with. Because these genetic changes are found in every cell of your body, the test can be done with a blood or saliva sample.
Some inherited genetic changes can increase a person’s risk of prostate cancer. Some may also affect how aggressive the cancer is.
It’s important to know that finding an inherited genetic change may have implications for your family’s risks. Your doctor or a genetic counselor can explain what your test results may mean for you and your relatives.
Understanding Somatic Testing
Somatic testing looks for genetic changes just inside the prostate cancer cells. Somatic testing can give information about the genetic features of your cancer. This may help your doctor decide which treatments will work best for you.
The test is most often done with a sample of cancer tissue taken during a prostate biopsy. If the cancer has spread to lymph nodes, bone, liver, or lung, tissue from any of those may also be tested. There is also an FDA-approved somatic test for blood called the FoundationOne Liquid CDX test that looks at more than 300 genes.
Who Should Consider Genomic Testing?
Not every person with prostate cancer needs genomic testing. The National Comprehensive Cancer Network (NCCN) recommends genomic testing for men with any of these:
- A family history of prostate cancer
- High- or very-high-risk localized prostate cancer
- Locally advanced prostate cancer
- Metastatic prostate cancer
- Ashkenazi Jewish ancestry
- Intraductal or cribriform (very aggressive) prostate cancer cells
How Can Genomic Testing Help Treatment?
The most important benefit of genomic testing is that it may help doctors customize your treatment. There are some examples below.
If You Have Prostate Cancer Surgery…
If you have surgery to remove your prostate, genomic testing may help doctors better understand your risk of the cancer returning. This may help guide decisions about using early follow-up treatment, such as radiation therapy or hormone therapy.
If You Have Advanced Prostate Cancer…
Genomic testing can be important for men with prostate cancer that has spread outside the prostate gland (advanced). This is because certain gene changes may make the cancer more likely to respond to specific treatments.
For example, some prostate cancers have changes in the genes BRCA1 and BRCA2. These genes normally help repair damaged DNA. Changes in these genes are known for their link to breast and ovarian cancer. In men with prostate cancer, they are linked to aggressive prostate cancer.
For some men with metastatic castration-resistant prostate cancer (mCRPC) and BRCA1 or BRCA2 gene changes, medicines called PARP inhibitors may be a treatment option.
Genomic testing can also look for microsatellite instability-high (MSI-high) gene changes. MSI-high prostate cancer is a rare subtype of prostate cancer. It occurs in 3% or less of prostate cancers. For men with mCRPC cancer and MSI-high gene changes, the immunotherapy medicine pembrolizumab may be a treatment option.
Should I Have Genomic Testing?
Genomic testing can give important information about prostate cancer, but it is not needed for every person with prostate cancer.
If you have high-risk localized prostate cancer, advanced prostate cancer, or other features that may make genomic testing useful, talk with your cancer doctor about genomic testing.
You can ask:
- Would genomic testing give useful information about my prostate cancer?
- Should I have germline testing, somatic testing, or both?
- Could the results change my treatment options?
- Could the results have implications for my family members?
- Should I meet with a genetic counselor?
Genomic testing is an important tool for customized prostate cancer care. If you think you may benefit from genomic testing, ask your doctor about it.