How Does Cancer Spread in the body?

There are 4 different ways by which cancer can spread in the body. Some cancers have a predilection to spread by a certain way.

Cancer can spread through local tissue, the lymph system, and the blood:

• Local Tissue Spread -
  The cancer spreads from where it began by growing into nearby areas.
• Lymphatic Route -
  The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymphatic vessels to the draining lymph nodes in the adjoining other parts of the body. (The lymphatic or lymph system involves an extensive network of vessels that passes through almost all our tissues to allow for the movement of a fluid called lymph. Lymph circulates through the body in a similar way to blood. There are about 600 lymph nodes in the body)
• Blood or Haematogenous Route -
  The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
• Perineural Spread -
  The cancer cells can spread along the nerve in the region of the tumor. Adenoid cystic carcinoma is a type of cancer that has a special predilection of spread by this route.

Cancer may spread from where it began to other parts of the body. When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumour) and travel through the lymph system or blood.

The metastatic tumour is the same type of cancer as the primary origin of the tumour. For example, if tongue cancer spreads to the lung, the cancer cells in the lung are actually tongue cancer cells and it is termed as metastatic tongue cancer.