If bowel cancer spreads to another part of the body, it is called metastatic or secondary (advanced), bowel cancer.
If the cancer in the bowel is not detected at an early stage, and removed and treated, cells can break off from that ‘primary’ tumour, enter the bloodstream or lymphatic system, and spread the bowel cancer to nearby lymph nodes or other parts of the body. A separate tumour may form in another part of the body.
A ’local spread’ is when the cancer has grown through the bowel wall and spread into surrounding tissues in the abdomen and pelvis. The cancer is known as ‘metastatic’ or ‘secondary’ (advanced) if it has spread to another part of the body. Spread to the lymph nodes is the most common.
The liver is the next most common site for bowel cancers to spread because the blood supply to the bowel (through the portal vein that carries blood from the intestines and spleen to the liver) passes through the liver as it returns to the heart. The lungs are also a common site of metastases because of a high blood flow that can carry cancerous cells from the bowel.