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Cancer Genetics

Risk Factors and Family Lines



My mother-in-law has just been diagnosed with breast cancer for the second time. I know having a family history of breast cancer is a risk factor. I`m wondering if this puts my daughter at a greater risk since it is her father's mother who has cancer? Does it make a difference in the risk factor if the breast cancer is on the mothers side of the family or the fathers side of the family? Thanks for your help.


This question is a little bit hard to answer with the information provided.  Hereditary forms of breast cancer are rare, but can be inherited from either parent, so the father's side of the family is important.  The other features in the family history that affect risk are the number of affected relatives, their ages of onset and whether or not there were multiple tumors or other related tumors (breast cancer in both breasts, ovarian cancer, etc), and ethnic background (Ashkenazi Jewish descent, for example). 

Based on the information provided, I'm not sure what the risk to your daughter would be.  It's unclear at what age your mother-in-law had cancer and whether this second cancer is a recurrence or a new tumor.  If it's in the other breast, it is likely a new tumor, which would make hereditary forms more likely, but still low unless there is Ashkenazi Jewish heritage or other family history.  If you are concerned, genetic counseling may be helpful for your family to explore these issues in more detail.  A genetic counselor in your area can be found on the website listed below.

Related Resources:

National Society of Genetic Counselors Resource Center
Inherited Breast Cancer

For more information:

Go to the Cancer Genetics health topic, where you can:

Response by:

Doreen M Agnese, MD Doreen M Agnese, MD
Clinical Associate Professor of Surgery and Internal Medicine
College of Medicine
The Ohio State University