Types of genetic testing available for prostate cancer

Types of genetic testing available for prostate cancer
Prostate cancer is the most common form of cancer diagnosed in men in the US. Although typically slow to progress, untreated prostate cancer may lead to serious health problems. Whether you have a family member with prostate cancer or you want to know more about its causes, let’s understand what science has to say about the genetics behind the disease.
Written by Dave Gennert, PhD candidate
Orchid offers advanced genetic testing for couples who want their child to have the best shot of a healthy life. “Genetics for Humans” is where we unpack how genetics impacts our everyday lives and the latest tools to help you build a healthier family.

What is prostate cancer, and how does it impact individuals?

Like all cancers, prostate cancer is uncontrolled growth of the cells that make up the body. The prostate gland itself is an organ only found in men that contributes to the production of semen. Prostate cancer typically starts as abnormal cell growth, causing the prostate gland to become enlarged. This growth in size can cause symptoms such as frequent urges and difficulty urinating as the prostate obstructs the urethra, as well as erectile dysfunction and painful or bloody ejaculate.

If prostate cancer progresses to a more advanced stage, metastasis (or, the spread of cancer cells to the rest of the body) is also possible. When this happens, cancerous cells can detach from the prostate and travel to other parts of the body such as the bones. These metastasizing cells can then start growing, leading to tumors developing in different organs. Cancers are generally more difficult to treat once they reach the metastasis stage, making it important to detect and treat prostate cancer early.

The good news is that 90% of the time, prostate cancers are detected at an early stage. The survival rate for these early-detected cancers is nearly 100%.

How common is prostate cancer?

In the US, prostate cancer is the most common form of cancer in men, affecting 1 in 9 men during their lifetime. In 2020 alone, 191,930 American men were newly diagnosed with prostate cancer. Prostate cancer usually appears in older men, having an occurrence of only 0.2% in men under 50 years old, then increasing with every subsequent decade (1.8% in those 50-59, 4.7% in those 60-69, 8.2% in those 70+).

Ethnicity also plays a role in the prevalence of prostate cancer. Black Americans have the highest rate of prostate cancer, with new diagnoses in 175.2 out of every 100,000 individuals per year. Other ethnic groups (white, 102.3; Hispanic, 92.0; Asian/PI, 5.67; Native American/Alaskan Native, 54.6) have different incidence rates, as well.

Does prostate cancer run in families?

Yes, prostate cancer has a large contribution from genetics and is known to run in families. An estimated 58% of a person’s risk for prostate cancer is believed to be determined by genetics. A family history of prostate cancer is actually one of the major risk factors for developing prostate cancer (along with age, ethnicity, and genetics). “Hereditary” prostate cancer – that is, often cases occurring in multiple first-degree relatives, occurring in successive generations, and with early onset (before 55 years old) – makes up around 5-10% of all prostate cancer cases.

Even without a strong family history of prostate cancer, having an affected close relative is still a significant risk factor. A single first-degree relative diagnosed with prostate cancer doubles one’s own risk; two affected first-degree relatives increases the risk to nearly 5-fold the risk in the general population; three affected first-degree relatives increases the risk to over 10-fold.

What are the genetic causes of prostate cancer?

The genetic causes of prostate cancer can largely be broken down into two categories: high-risk single gene mutations and a combination of many genetic variants.

Single gene mutations

The genetic mutations that lead to families with high incidences of prostate cancer are typically high risk mutations that often lead to more aggressive and earlier-onset forms. One example of these high-risk genetic mutations is found in the gene HOXB13, a gene important in prostate development. Other high-risk mutations include known cancer-causing genes, such as BRCA1 and BRCA2. Perhaps more well-known for their association with breast cancer, mutations in these two genes have been found to increase the risk of prostate cancer in men. Patients with Lynch syndrome, a genetic condition causing hereditary colon cancer, also have a higher risk of developing prostate cancer due to mutations in important DNA-repair genes.

Families with a strong history of prostate, breast, or pancreatic cancer may benefit from genetic testing to find potential high-risk mutations. Talking to a cancer genetic counselor may help determine if single-gene testing is appropriate for you and your family.

Combination of many genetic variants

Most cases of prostate cancer, though, don’t occur in family clusters and aren’t caused by single high-risk mutations. Instead, genetic risk is a combination of many genes and genetic markers across the genome. Throughout the genome, the DNA sequence variants that make each person unique also work together to increase or decrease each person’s risk for developing a number of conditions, including prostate cancer.

Is there a genetic test for prostate cancer?

Yes, there are tests available to measure the genetic predisposition to prostate cancer. Testing can be broken down into two types, depending on which genetic factors are measured: testing for specific high-risk single-gene mutations and advanced genetic predisposition screening for increased risk.

High-risk single-gene testing

A strong family history of prostate or other cancers may indicate a high-risk single-gene mutation as a cause. As inherited prostate cancer is often more aggressive with earlier onset, those with inherited cancer risk may wish to seek out genetic counseling to see if single-gene testing is appropriate.

Testing for mutations in a panel of cancer-associated genes will help determine if one of these commonly mutated genes is contributing to a family’s high risk for cancer. Individuals who have previously been diagnosed with prostate cancer may also benefit from genetic testing. The results from these tests may affect the monitoring plan for prostate cancer, lifestyle changes to prevent disease, and even which medications are most appropriate for treating prostate cancer.

Advanced genetic screening

If you are concerned about cancer predisposition but don’t have strong indicators for single-gene cancer mutations, such as family history or previously diagnosed prostate cancer, genetic screening may help assess the risk of developing cancer. Genetic screening can tell you if you are more or less likely to develop prostate cancer than the average person based on your genetic background.

This is done by factoring in all the variants across the genome that we know increase the risk for prostate cancer. Individually, each of these variants has a low impact on risk, but when combined, they can lead to significant risk for disease. A recent study on over 140,000 people identified over 160 of these variants.

Taken together, these risk variants can provide a genetic risk score, unique for each person. An individual’s risk score will tell them their relative risk compared to the general population.Research has shown that the prostate cancer risk score can identify individuals in the 90th-99th percentile for risk (2.69-fold risk) and in the top 1% for risk (5.71-fold risk).

With Orchid’s advanced genetic testing, you can get a sense of your genetic predisposition to prostate cancer and remove some of the guesswork on what you can pass on to your future children.

What actions can I take based on the information from a genetic test for prostate cancer?

If you or your future child has an elevated genetic risk for prostate cancer, the risk of developing prostate cancer at some point in life can be over five times higher than in the general population.

The useful thing about your results is that if you identify certain genetic vulnerabilities that can impact you or your future children, you can potentially do something about it and mitigate these risks. Ways you can act on your results include:

  • Seek cancer genetic counseling early.  If you have a personal or strong family history of early-onset or more aggressive forms of prostate cancer, a genetic counselor can help you understand the risks for you and your family. Your health care team can integrate your family history of prostate cancer, ethnic background, and prostate cancer genetic risk score to better assess your overall risk.
  • Form a plan with your doctor.  If caught in the early stages, prostate cancer has an over 99% survival rate. An elevated genetic risk may call for a more careful screening plan in order to catch prostate cancer early, which may include blood tests (PSA screening) or digital rectal exams. A patient’s genetic background may also impact the effectiveness of various treatment options.
  • Embryo screening to reduce your child’s potential genetic risks.  Embryo screening allows you to assess each embryo’s genetic risk for prostate cancer and other common conditions. This allows you to prioritize the transfer of embryos with the lowest genetic risk and thus reduce your future child’s genetic risks.

Key takeaways

  • Prostate cancer is a common form of cancer, representing the leading cause of cancer in men in the US.
  • Age, ethnicity, family history, and genetic background are the main risk factors for developing prostate cancer.
  • Advanced genetic testing can now quantify the genetic component to prostate cancer for you and your family.
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Orchid offers advanced genetic testing for couples planning on building their family. We use advanced tools and smart, caring humans to help you give your future children the best shot of a healthy life. Conceive with greater confidence and peace of mind
2/18/2021
Genetics
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