There are several online tools that assess breast cancer risk. A good one is the Breast Cancer Risk Assessment Tool from the National Cancer Institute, which uses the “Gail method” to calculate a woman’s risk of developing breast cancer over the next five years, as well as lifetime risk. You can complete it online and discuss the results with your health care provider, who can then advise you on what steps, if any, you should take.
The assessment asks about several breast cancer risk factors, such as age at first menstrual period, when you had your first child (or if you had no children), and whether you have a first-degree relative with breast cancer or have had a breast biopsy. Not all risk factors are included, however, and the tool is not for all women, such as those who have already had breast cancer or precancerous changes.
To be included in tamoxifen or raloxifene trials, higher-risk women have been defined as having at least a 1.7 percent chance of developing breast cancer in the next five years. But there is no official cutoff for defining increased risk, and the U.S. Preventive Services Task Force, in its latest recommendations, concluded that women who are most likely to benefit from these drugs have an estimated five-year breast cancer risk of three percent or higher. The greater your risk, the greater the benefit.
Keep in mind that even if you have higher-than-average risk, your absolute risk is still low. For example, if the calculator says you have a three percent risk of developing breast cancer in the next five years, this means there’s a 97 percent chance that you won’t develop it.