Stage 3B cancer is a subcategory of stage 3 breast cancer in which the tumor is of any size and has spread to tissues near the breast. In this stage, the cancer has spread to the surrounding lymph nodes, explains Mayo Clinic.
In stage 3B cancer, the tumor has invaded the breast skin and the chest wall. This stage is characterized by noticeable swelling in the breast area, ulcers and inflammation. At this stage, the cancer may have spread to up to nine lymph nodes. Although this is an advanced stage of breast cancer, several effective treatment options exist, according to the National Breast Cancer Foundation.