Stage 1 breast cancer is localized to its origin
Stage 1 breast cancer is invasive but is smaller than 2 centimeters. It has already begun to spread to healthy tissue but has not traveled anywhere besides its location of origin. There are two stages of stage 1 - stage 1A and stage 1B. In stage 1A, there is absolutely no lymph node involvement. In stage 1B, there are only small amounts of lymph node involvement and the tumor is less than 2 centimeters in size.