What term refers to the spread of tumor or cancer cells from their original site?

The term that describes the spread of tumor or cancer cells from their original site is known as metastasis. This process involves the dissemination of cancerous cells through the bloodstream or lymphatic system to other parts of the body, where they can establish new tumors. Metastasis is a critical concept in oncology because it significantly affects the staging, treatment options, and prognosis of cancer patients.

Proliferation generally refers to the rapid increase in the number of cells, which can occur in both healthy tissues and tumors, but it does not specifically imply the movement to different locations in the body. Invasion refers to the local spread of cancer cells into surrounding tissues but does not encompass the broader process of spreading to distant sites. Diffusion, while it describes the movement of substances from areas of higher concentration to areas of lower concentration, is not specifically related to cancer cell movement or tumor behavior. Thus, metastasis is the most accurate term for the described phenomenon.