The ripple effect: What to know when your prostate cancer is hereditary

Gloria Morris, MD, PhD (photo by Jim Howe)

Upstate medical oncologist Gloria Morris, MD, PhD, who specializes in cancer risk assessment and genetic testing for hereditary cancers, answers six important questions about prostate cancer:

What percentage of prostate cancers are hereditary?

“Only a very small percentage of all cancers are hereditary.

“Even though prostate cancer is among the most commonly diagnosed cancers in men — analogous to breast cancer being the most common in women — only 10 percent of men with aggressive forms of prostate cancer may have a hereditary component. That is, they may have inherited the predisposition to develop prostate cancer by inheriting a gene mutation, which can also overlap to cause a predisposition for breast cancer.”

Since the genetic connection between breast and prostate cancers became evident in recent years, genetic counselors now look at the cancer risk for both male and female family members of men with hereditary prostate cancer. She says, “when I see women with hereditary breast cancers, I always look around for its ripple effect. There could be other women or men in her family who could benefit from genetic testing.”

If you have a specific gene mutation, does that mean you will develop cancer?

“It does not mean that a person is doomed to develop prostate cancer or breast cancer,” Morris says.

Instead, she says someone who learns of a genetic mutation may need earlier and more frequent screening to stay ahead of any possible cancer development, especially if the person has a family history of cancer.

(Click here for a podcast where Gloria Morris, MD, PhD, discusses the hereditary factors involved in prostate cancer.)

How many genes are we talking about?

“Eight to 10 breast cancer genes are known to increase the risk of prostate cancer if that same mutation is passed on.

“The genes that have been identified in men who have aggressive prostate cancers actually are breast cancer genes,” she says. “BRCA2, for example, imposes up to a 7% lifetime chance of developing prostate cancer in men. The risk for breast cancer developing in a woman with that gene is much higher, anywhere from 40% to 80% over one’s lifetime.”

Who should consider genetic testing?

“A man who has several family members with prostate cancer or multiple family members with other possibly associated cancers — colon, ovarian and breast cancers all overlap to possibly elevate a prostate cancer risk.

“Through blood testing and/or saliva testing, we can send for DNA sequencing of the known hereditary prostate cancer genes.”

Morris says commercially available genetic test kits may only test for portions of genes and may not target the ones most relevant to an individual. Instead, she recommends seeking care at an established clinical genetics program.

The program at the Upstate Cancer Center accepts referrals directly from patients or from primary care providers.

Are mutations passed on to children?

“In our numbered pairs of chromosomes, we inherit — usually — one copy that is normal from one parent, and one copy that might be mutated. When those chromosomes split, when we pass on half our genes to each child, there is a random 50/50 chance of passing on that mutation.”

The parents, children and siblings of a person with a hereditary form of prostate cancer are recommended to be tested for that mutation.

At what point should children be tested?

“For the gene mutations that could cause adult-onset cancers, we recommend testing anytime over the age of 21. There are a lot of psychological impacts of carrying a gene mutation. However, understanding the ramifications is a good idea.”

This article appears in the fall 2019 issue of Cancer Care magazine.