Some colon cancers are secondary to colon polyps or choroidal adenomas, and some colon cancers develop directly. At the beginning, the mass is small and invades the shallow part of the intestinal wall, that is, within the mucosa or in the mucosal layer, and many patients have no symptoms. If the tumor progresses further, the tumor will increase in size and infiltrate deeper into the intestinal wall, it may invade into the submucosa, muscle layer or even the plasma layer. If the tumor invades the muscular layer, lymph node metastasis may occur, including intra-hypophyseal lymph node metastasis and root lymph node metastasis may also occur. If the mass increases further and breaks through the intestinal wall, it may invade the organs surrounding the intestinal wall, including the bladder, kidney, and even the abdominal and pelvic walls, and may develop distant metastases, including liver and lung metastases.