Why Genetic Testing Is So Important
- One of the most empowering aspects of modern prostate cancer care is the emphasis on tailored treatment. This means your care plan isn’t a one-size-fits-all solution; instead, it’s a collaborative effort between you and your medical team, shaped by what truly matters to you.
- Genetic testing, which can help your team identify key factors about your cancer that might help them determine the best treatment approach, plays a key role in tailored treatment.
- Every patient with metastatic prostate cancer should consider having genetic testing. This becomes more important if your cancer has stopped responding to hormonal therapy — a state known as castration-resistant prostate cancer.
- After a diagnosis, it’s crucial to speak to your doctor about genetic testing and if it is necessary/could be helpful for your individual case.
“The journey of understanding prostate cancer so that you can better treat it and fight it starts from day one,” Dr. Eleni Efstathiou, a medical oncologist at Houston Methodist Leading Medicine, tells SurvivorNet, stressing the idea of “shared decision making.”
Read MoreGenetic Testing: Tailoring Treatment to You
One of the most empowering aspects of modern prostate cancer care is the emphasis on tailored treatment. This means your care plan isn’t a one-size-fits-all solution; instead, it’s a collaborative effort between you and your medical team, shaped by what truly matters to you.
Genetic testing can help doctors determine whether your cancer is more likely to respond to certain treatment approaches.
“In my clinic … we have integrated a systematic approach to genomic testing,” Dr. Efstathiou explains. “…It is the testing that helps you understand the DNA of the tumor and the DNA of the patient.”
“There’s germline testing, which is trying to better understand if there is a mutation within the DNA of the patient that leads to not only the cancer evolving, but also progressing. And then there’s the testing of the tumor that lets you understand whether there are mutations on there that can be targeted, or whether there are mutations that can tell you how aggressive this cancer is. So you can make plans to be also more aggressive on the treating end,” she adds.
Dr. Efstathiou explains that at Houston Methodist, it has become policy to offer all patients with advanced prostate cancer genetic testing. If your oncologist or treatment center does not recommend genetic testing, it is something you can and should bring up.
These genetic tests can also pick up mutations that could put your family members at risk.
“If we find that in your own DNA there is a mutation that is cancer causing … We need to talk to you about that, because it could cause another cancer beyond prostate cancer,” she says. “And importantly, there’s [a chance] that your kids, or somebody who’s your sibling, may have a mutation. So we offer that testing to them as well. And that knowledge provides you the opportunity to screen early for such cancers and save lives. For me, it’s one of the most important parts of our practice.”
Dr. Efstathiou explains that the chances of finding such a mutation in men with advanced prostate cancer are about 12%.
However, with more comprehensive germline testing, such the one performed at Houston Methodist, these chances rise to 15-16%.
Next-Generation Sequencing
Next-Generation Sequencing (NGS) is a type of molecular testing. It is a comprehensive panel that looks for alterations or mutations in your tumor.
It’s like a modern toolbox used by scientists to quickly and affordably read the instructions of an organism’s DNA or RNA. This has helped researchers read a lot of genetic information fast, like reading a whole book, so they can understand entire sets of genes, find differences in genes, and study how genes work in a really big way.
To collect a sample for testing, your doctor will use part of your tumor tissue or do a small blood draw. Tumor-specific testing like this is called somatic testing.
Which Mutations Matter For Prostate Cancer?
Current national guidelines recommend that anybody diagnosed with metastatic prostate cancer undergo genetic testing. Those with node positive disease or high risk prostate cancer may also benefit.
DNA damage is an ongoing occurrence that necessitates a sophisticated web of repair mechanisms to uphold the integrity of the genome.
In healthy cells, DNA may sometimes act strangely. When that happens, DNA is repaired via several mechanisms including the homologous recombination repair (HRR) pathway. In the presence of HRR gene mutations (HRRm), cells are unable to effectively repair broken DNA — and that could lead to cancer.
The most well-known of these homologous recombination repair genes are called BRCA1 and BRCA2.
Another genetic test done for prostate cancer is checking for homologous recombination repair gene deficiency (HRD). HRR gene mutations occur in approximately 25% of patients with advanced prostate cancer.
Up to 15% of men with metastatic and 10% of men with localized prostate cancer have mutations in homologous recombination repair (HRR) genes, such as BRCA2, BRCA1, ATM, CHEK2, PALB2, and mismatch repair (MMR) genes (MLH1, MSH2, PMS2 and MSH6).
After a diagnosis, it’s crucial to speak to your doctor about genetic testing and if it is necessary/could be helpful for your individual case.
Why Get Genetic Testing
Once again: everybody who is diagnosed with metastatic prostate cancer should talk to their doctors about getting genetic testing.
Testing tumors for specific genetic changes is important for two reasons. First, as more targeted drugs enter the market, it is increasingly possible to target the specific alterations that drive someone’s tumor. And second, some of these genetic alterations, known as germline alterations, are associated with familial predisposition to the disease, which may prompt screening in other family members.
Types of NGS Testing On The Market
There are a number of tests you may encounter, depending on where you are getting treatment and what you are getting treatment for.
Here are some of the common ones currently on the market:
- FoundationOne®CDx looks at 324 genes in solid tumors and says it can takes up to 12 days for results. Test results include microsatellite instability (MSI) and tumor mutational burden (TMB) to help inform immunotherapy decisions.
- OmniSeq Insight provides comprehensive genomic and immune profiling for all solid tumors. It looks for 523 different genes. Test results include microsatellite instability (MSI) and tumor mutational burden (TMB), as well as PD-L1 by immunohistochemistry (IHC).
- Cobas EGFR Mutation Test v2 identifies 42 mutations in exons 18, 19, 20 and 21 of the epidermal growth factor receptor (EGFR) gene. It is designed to test both tissue and plasma specimens with a single kit, and allows labs to run tissue and plasma on the same plate simultaneously.
Questions To Ask Your Doctor
- What sort of genetic testing do you recommend in my case?
- Am I a good candidate for next-generation sequencing?
- What are my chances of having a mutation that has a targetable drug?
- How long will it take to get my NGS testing results?
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