Cancer that runs in families isn’t always inherited

May 22, 2017

Genetic does not mean genetic 5-22 inside — Inherited genetic diseases are passed down through families, but family history of a disease doesn’t always mean it’s genetic.

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Learning family members have cancer or other serious illnesses may bring up questions about your risk.

You may be wondering if you’ll get the same type of cancer or if you should get genetic testing for a disease that has affected a few relatives.

“The terms ‘genetic’ and ‘hereditary’ are often used interchangeably when it comes to diseases, but they don’t mean exactly the same thing,” said Kyle Salsbery, a Marshfield Clinic Health System genetic counselor.

Genetic vs. hereditary vs. family history

Cancer is a genetic disease. That means it is caused by changes in our genes that control how cells function. Genetic changes can happen during someone’s lifetime, or they can be passed down from parents.

Some, but not all, genetic conditions are hereditary. Hereditary means they’re passed down from parents.

“If you have a hereditary disease, your parents may be carriers or affected by the disease as well,” Salsbery said.

Scientists can pinpoint several inherited genetic differences that predispose people to certain types of cancer. Breast, ovarian, colorectal and other cancers sometimes are hereditary.

Diseases that are common in your family may not be caused by inherited genetic changes. Salsbery calls these conditions familial. They’re often caused by multiple factors shared among families, like environment and lifestyle. There may be a genetic cause that isn’t a strong factor in developing the disease or that scientists haven’t figured out yet.

Sporadic diseases don’t have an inherited genetic component and aren’t common in your family.

Reasons to get genetic testing

Genetic testing isn’t always needed when you have a family history of cancer. Some examples of when genetic testing is recommended may include:

Early onset of the disease: Diagnosis before age 50 is considered early onset for most cancers.
Multiple generations affected by the same type of cancer.
Cluster of rare cancers in the family.

Genetic testing for diseases that are very common in the general population or involve many risk factors may not be helpful, Salsbery said.

Practical steps after genetic testing

A test that shows a genetic difference that puts you at greater risk for a certain type of cancer doesn’t mean you’re definitely going to get sick or you can’t do anything about it. Maintaining a healthy lifestyle can reduce anyone’s risk of cancer even if they have a strong genetic risk factor.

If testing shows there isn’t a known genetic risk factor for a disease that’s common in your family, it’s still important to keep track of your family history.

“Families tend to share similar environments and lifestyles that can put them at greater risk for certain diseases,” Salsbery said. “You may need more screening than what’s recommended for the average person because of your family history.”

4 responses to “Cancer that runs in families isn’t always inherited”

Eldine Cole

May 25, 2017

When the genetic research at Marshfield Clinic was just getting started, my wife and I both submitted to testing and were paid either 20 or 25 dollars apiece for our participation. Her daughter has had numerous health issues throughout her life and I was wondering if there is information available in my wife's genetic profile that would be of helpful interest to her daughter's medical team in Michigan? If this sounds like a possibility, I could come in to the Research Facility and meet with someone to pursue this more specifically.

Reply
1. Kirsten Shakal, Shine365 Editor
  
  Jun 2, 2017
  
  Hi, Eldine. Thank you for reaching out. I apologize for the delay in our response – I wanted to be sure I tracked down the right information for you.
  
  I spoke with Terrie, a research coordinator at Marshfield Clinic Research Institute, regarding your comment and question.
  
  With the context you’ve provided, she feels your wife was probably involved in a PMRP bio-bank (personalized medicine research project). In these projects, it was determined that results are not shared with participants:
  
  1) Testing does not meet CLIA regulations; it is for research purposes only. In other words, it is not meant for clinical use.
  2) Testing is not comprehensive. We only have a small portion of the DNA, so the data would be limited.
  3) Genetic information from your wife has only a 50-percent chance of being passed down to her daughter. Again, this makes the research information less useful for clinical purposes.
  
  Terrie recommends instead working with a geneticist: https://www.marshfieldclinic.org/Specialties/medical-genetics-services. A genetic counselor will talk through family history with you and help determine the next best steps.
  
  I hope this helps. Please let me know if I can provide you any further information on our genetics team. -Kirstie
  
  Reply
  1. Eldine Cole
    
    Jun 2, 2017
    
    Dear Kirstie,
    You didn't tell me anything I didn't already know but then I had forgotten. Thanks for taking the time to sort out the answers for me. You would be disappointed if no one ever responded to your topics wouldn't you? So at least now you know some people read your posts and give some thought to them. Obviously, not all of the info is relevant to every person but usually there is something for me each week. Keep up the good work.
  2. Kirsten Shakal, Shine365 Editor
    
    Jun 5, 2017
    
    My pleasure, Eldine. Thank you for reading Shine365! I appreciate the followup response. -Kirstie