What does "metastasis" mean in the context of cancer?

Metastasis refers to the process by which cancer cells spread from the original (primary) site of the tumor to other, often distant, parts of the body. When cancer cells metastasize, they can penetrate the walls of lymphatic and blood vessels, allowing them to travel through the bloodstream or lymphatic system to establish new tumors in other organs or tissues. This is a critical aspect of cancer progression and is associated with more advanced stages of the disease, as metastasis can complicate treatment and significantly worsen the prognosis. Understanding metastasis is essential for developing effective treatment strategies and for managing patients in clinical practice.