Germline Genetic Testing for Prostate Cancer

Cancer is caused by a combination of genetic and environmental risk factors. Mutations (abnormal DNA) in certain genes have been identified that greatly increase the risk of certain types of cancer, including prostate cancer. In the US, prostate cancer is the second most common type of cancer affecting men and is the second most common cause of cancer death in men. Genetic testing can help identify known mutations that increase prostate cancer risk and predict cancer severity. This testing can also help identify potentially increased cancer risk in family members.

Key takeaways:
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    Cancer has both inherited genetic risk factors and acquired environmental risk factors.
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    Germline genetic testing can find inherited gene mutations. Specific germline mutations have been identified that increase the risk of several types of cancer.
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    Germline genetic testing can help determine the best treatment for prostate cancer and other cancers.
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    Men with severe prostate cancer or a family history of related cancers should undergo germline genetic testing.

Cancer explained

Cancer occurs when mutations in DNA cause cells in the body to grow and divide uncontrollably, forming tumors and metastasizing (spreading) to other parts of the body. Cancer cells begin as normal cells, but damage to the DNA in those cells transforms them into cancer cells. Normally, cells repair damaged DNA or die off, but certain mutations can lead to cancer or an increased risk of cancer.

DNA damage can come from environmental exposures, such as ultraviolet radiation or certain chemicals, or it can be inherited from a parent. Gene mutations passed from parents to children are called germline mutations, meaning that those abnormal genes are present in eggs and sperm. When germline mutations are inherited, they are present in every cell of the body and can be passed on to offspring. Under the right conditions, these mutations prevent normal DNA repair and cell death, leading to cancer.

What is germline genetic testing?

Germline genetic testing looks for known mutations in specific genes in a person’s DNA. For this type of testing, DNA can be collected from any healthy cells in the body, typically from a cheek swab. Specific mutations in certain genes have been identified that increase the risk of specific types of cancer. Germline genetic testing is different from genetic testing performed on cancer cells. Somatic genetic testing looks at specific mutations inside cancer cells. Both somatic and germline genetic testing can be used to help determine what cancer treatments will work best for an individual.

Genes associated with prostate cancer

Genes are sequences of DNA that are used to make specific proteins. If the gene for a protein has a mutation, it can prevent that protein from functioning properly. Prostate cancer risk is associated with specific mutations in many different genes. Inherited mutations of the BRCA1 and BRCA1 genes, typically associated with breast cancer, are present in 11.8 percent of men with metastatic prostate cancer, compared with only 4.6 percent of men with localized prostate cancer. Other genes involved in prostate cancer include ATM, HOXB13, MLH1, MSH2, MSH6, PMS2, and others. Each of these genes associated with prostate cancer risk encodes proteins that are involved in DNA repair. When cells cannot repair damaged DNA it normally leads to cell death, but it can also lead to cancer.

How is germline genetic testing used?

Germline genetic testing is used to help guide treatment strategies, predict cancer outcomes, and identify familial cancer risk. There are many ways to treat cancer, but some cancers respond better to certain therapies depending on the genetic makeup of the cancer cells. Some known mutations in healthy cells have also been found to predict how well specific cancer treatments will work. This includes a class of targeted cancer drugs called PARP inhibitors that can be very effective in people with these specific mutations.

Genetic testing is not only useful for the person being tested; it can also help determine cancer risk for family members who may carry the same mutation. Genetic counseling with an oncologist or genetic counselor is needed to understand how your specific genetic makeup affects the risk of cancer for yourself and your family members.

Who should have germline genetic testing?

Not all men who have prostate cancer need germline genetic testing. Testing is recommended for men at higher risk of having specific germline mutations based on the severity of their prostate cancer or a family history of certain types of cancer, including breast, ovarian, and prostate cancer. Germline genetic testing is not recommended for men with localized prostate cancer (cancer that has not spread to lymph nodes or other parts of the body) and no family history of related cancers. If you have prostate cancer you should speak to your doctor about whether genetic testing can help you and your family.

Cancer and germline genetic testing

Germline genetic testing is a powerful tool in the fight against prostate cancer and other common, deadly cancers. Certain germline mutations passed from parents to their children can significantly increase the risk of prostate cancer. Those same mutations can also increase the risk of other cancers, such as breast cancer and colon cancer, in both the individual being tested and their immediate family. Germline genetic testing can help doctors find the best treatment for prostate cancer as well as help family members understand whether they are at higher risk of certain cancers. Germline genetic testing is not useful for everyone with prostate cancer; talk to your doctor about whether genetic testing is right for you.

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