Why do tumours metastasize to local lymph nodes?

Answer 1

Lymph is an almost-clear fluid that drains waste from cells. This fluid travels in vessels to the Lymph Nodes, small bean-shaped structures that filter out unwanted substances, such as cancer cells and bacteria, out of the fluid. Lymph Nodes can become filled with cancer cells.

The spread of cancer to other sites is called metastasis.

Answer 2

Cancer cells can slip through tissue. But the lymphatic system is sort of the sewer pipes of our cells and tissue. It is an easy path for the cancer cells.
I am a melanoma survivor because my darling wife's sharp eyes noticed a funny looking spot on my back that changed.
My Dr. suggested and performed a wide excision and removed the sentinel node. They injected blue dye around the site of the cancer and then went and searched for the blue lymph node or the one that serviced that area of my back. They removed it and biopsied it. It had no cancer. If cancer had been found, they would have removed all those lymph nodes in that area.

Answer 3

The lymphatic system is one of the body's first defenses against infection. They are supposed to work to contain the infection and keep it from spreading further, thus when you get a sore throat it is often accompanied by inflamed lymph nodes, the same with cancer. However, sometimes the lymph nodes can't keep up with the invasion so to speak and it spreads further.