The probability of breast cancer metastasis is unclear, with individual differences, and is related to various factors such as the pathological type of breast cancer and whether timely and effective diagnosis and treatment are carried out. Clinical research shows that breast cancer has a strong ability to spread to distant sites through bloodstream, and it appears earlier, and the common metastatic sites are lymph nodes, lungs, bones, liver, pleura, brain, etc. In general, if breast cancer is not treated actively and effectively in the early stage, it will develop into a cancerous disease. Generally speaking, if breast cancer fails to undergo active and effective treatment in the early stage and develops into the middle or late stage, the probability of metastasis is very high at this time. In addition, the malignancy degree of highly differentiated breast cancer is relatively low, and metastasis occurs later or is not easy to occur. If the differentiation degree of breast cancer is low, its malignant degree is high, and the probability of metastasis at early stage is also high. Once diagnosed with breast cancer, patients should cooperate with doctors to carry out systematic treatment as early as possible to reduce the probability of metastasis.