In Stage I and II, the cancer is considered early but may have begun to invade nearby tissue or lymph nodes. Stage III is more advanced and may involve multiple lymph nodes or nearby structures. Stage IV, also known as metastatic breast cancer, occurs when cancer spreads to distant organs like the lungs, liver, or bones.The prognosis of breast cancer depends on the stage at diagnosis, tumor biology, hormone receptor status, and response to treatment. Each stage is determined by factors such as tumor size, lymph node involvement, and whether the cancer has spread to other parts of the body.There are five main stages of breast cancer, ranging from Stage 0 to Stage IV. Stage 0 (carcinoma in situ) represents the earliest form, where abnormal cells are confined within the ducts or lobules.