Christina Applegate stunned the world by bravely announcing she is battling breast cancer. Fortunately, the "Samantha Who?" star caught the cancer at an early stage.

Now, "Extra" is going one-on-one with NY oncologist Dr. Sharon Rosenbaum, who shared three important tips for breast cancer prevention:

"Get your mammogram every year, and do your own self exam every month," shares Rosenbaum. "Finally, it's very important to know that not all lumps are cancers, so women should not be scared if they do feel something -- but it's certainly something they should see their doctor for."