The four main ways of cancer metastasis are direct infiltration, bloodway metastasis, lymphatic metastasis and plantation metastasis. 1. Direct infiltration: for example, bladder cancer can directly metastasize to surrounding tissues such as rectum. 2. Bloodway metastasis: it is the most important way of metastasis. Cancer cells can circulate to any part of the body by filling up the blood of the whole body, and lungs and bones are the two most common metastatic locations. 3. Lymphatic metastasis: lymphatic system exists in many parts of the body, and cancer cells can be transferred through abundant lymphatic system, for example, the most common metastatic site of liver cancer is hilar lymph nodes. 4. Plantation metastasis: high level cancer cells can be planted in low level plasma membrane directly after shedding, the most common one is Kukenberg’s tumor, which is formed when stomach cancer metastasizes to ovary.