Cancer Genetics Program

Cancer is a common disease. One out of every 3 Americans will develop cancer during their lifetime. Many of us have one or more family members affected by cancer. The good news is that about 90% is sporadic and caused by a variety of factors, including genetic makeup and environmental influences. Only about 5% to 10% of cancer is hereditary. It is important to identify families with a hereditary susceptibility to cancer because in many cases they can take steps to reduce their risk or prevent cancer from occurring.

Characteristics of hereditary cancer susceptibility include:

The same or related types of cancer in two or more close relatives on the same side of the family (close relatives are parents, siblings, children, grandparents, grandchildren, aunts, uncles, nieces, and nephews)

  • Cancer in multiple generations
  • An early age at diagnosis (usually under age 50) 
  • Multiple primary tumors or bilateral cancer (like cancer in both breasts)
  • A pattern of cancer consistent with a specific hereditary cancer syndrome (e.g. breast & ovarian or colon & uterine)

If you are concerned about the possibility of hereditary cancer risk in your family, you may want to begin by documenting your family history.

  • List all family members on both sides of the family and their relationship to you (e.g. paternal grandmother, maternal uncle)
  • List current age or age at the time of death; include cause of death if known
  • For family members with cancer, list the type of cancer they had and their age at diagnosis
  • If there is a question about the diagnosis try to clarify with medical records.  For example, “female cancer” could be cervical, uterine, or ovarian and all have different implications if the family is being evaluated for a possible hereditary cancer risk
  • Think about possible environmental influences (e.g. smoking, asbestos exposure)

For additional information about the importance of your family’s health history and to access the My Family Health Portrait Web Tool see the Surgeon General’s Family History Initiative at 

Click here for a printable brochure about Cancer and Your Family Tree

Click here for general information about cancer biology, diagnosis, and treatment from CancerQuest