Who Should Consider Genetic Testing?

The majority of cancers are considered to be sporadic or occur by chance, and in patients without a family history of cancer. Only a small portion of all cancers, approximately 10%, is considered to have an underlying hereditary cause. This happens when individuals are born with specific genetic changes that can predispose them to cancer. 

A gene is like a blueprint that gives your body instructions on how to properly grow and develop. At Moffitt, we are interested in an important group of genes known as "tumor suppressor" genes. Their role is to give the body instructions on how to prevent certain types of cancers from growing. If a person is born with a genetic change (called a mutation) that causes that gene not to work, then that person’s body is not as protected against cancer.

A genetic test analyzes these genes to determine if they are, or are not, working as they should be. Modern technology is used to read through this group of genes to identify if a mutation is present.

Features that could indicate a possible hereditary predisposition to cancer include:

• Diagnoses at unusually young ages, specifically under age 50
• A history of multiple cancers in the same person
• Bilateral cancers, such as cancer of both breasts or both kidneys
• Diagnoses of rare cancer types, like ovarian or pancreatic cancers
• Strong family history of cancer, especially if there are multiple family members with the same cancer type or related cancer types (i.e. breast and prostate)
• Certain ethnicities, such as those with Ashkenazi Jewish, that are known to have higher risks of inherited cancer
• Tumor testing that identified a genetic marker within the tumor

In general, it is best practice to initially test a family member who has had cancer. Testing the person most likely to have a hereditary risk is the most informative way to obtain information for the cancer risk in the remainder of the family.