If it is not treated, the cancer will grow and spread to nearby parts of the body. For example, it may spread to the bile duct, duodenum (first part of the small intestine) and colon, and to the spleen or lymph nodes, which are part of the body's lymphatic system.

Once the cancer cells get into the bloodstream or lymphatic system they may travel to other areas of the body – most usually the lungs or liver – and start growing there. These cancers are called secondary cancers or metastases.