Breast Cancer is an important disease that affects many women, excluding self-examination and screening by mammogram, nothing helps women or their physicians to know what risk they run of suffering from breast cancer during the course of their lives. There have been many studies detailing the relative risks of breast cancer based on different factors and applications to calculate the breast cancer risk, but none implemented in a way to show lifetime risk. This paper presents an on-line tool (called Breast Alert) to calculate the lifetime breast cancer risk for women using a proposed model. With Breast Alert, physicians can make a quick screening for women when they consult. It is easy to use and intuitive. In a few minutes, physicians can have a lifetime breast cancer risk. This tool does not replace tests like self-examination, breast screening or detection by other options, but allows for the proper precautions to be taken and calls attention to the expected lifetime risk. Nowadays, 300 women (between 20 and 75 years old) from different countries have used the system and most of them (80%) have a higher than normal chance of contracting breast cancer. With these results, it is important to alert of the importance to make an early prevention of breast cancer in different women groups.