Having genetic testing available has been a very successful method of assessing risks of cancer in families with strong histories of cancer. When it is positive, we have guidelines to assist caregivers and patients how to potentially manage their risk . When it is negative and there is a known mutation in the family, then that person did not inherit it. We call this a “true negative” and recommend screening as we would other persons based on age without that strong family history.
But what about those people who have a family history but no mutation is found? I often hear this in my clinic, ”Sure, my mother had cancer but it wasn’t genetic so I am not at risk.” This really isn’t the case, so let’s talk about your risk.
First, if you have a strong family history and no mutation was identified, then you have likely met with a genetic professional who looked at your family’s cancer history . If no mutation, then we go back to your family history. We can use different mathematical models to estimate your risk by taking into account for how many people are in your family, cancers diagnosed, and the ages of diagnosis. We will often recommend you start your screening 5-10 years earlier than the earliest age of cancer diagnosed in your family. If your lifetime risk is over 20 percent, we may recommend adding in a breast MRI in addition to a mammogram for your screening.
Remember, the BRCA genes only account for 5-10 percent of all the breast cancers, which means the remaining 90-95 percent of the time, the cancer is related to likely a perfect storm of other risks.
If it doesn’t look like you have a strong family history but you have other risk factors or you just want to know what your risk is, we tend to use another tool that can be found easily on the internet.
This tool, also called the Gail model (after Dr. Gail who developed it), will ask you several questions that helps look at your individual risk. Questions include your age, age you had your first menstrual cycle, age of first birth, number of first-degree family members with breast cancer and your history of breast biopsy. This model only applies to women who are 35 years of age or older.
You and your doctor ay use this tool to identify if you are at high risk (5-year risk of >1.66). If so, you may be a candidate for a prevention medication that blocks estrogen such as tamoxifen if you are premenopausal, or raloxifene, anastrozole or exemestane if you are postmenopausal.
Models are only estimates and no one can tell you for sure your cancer future, so get informed as to your personal risk and make your health care prevention plan with your health provider.