# What is Metastasis?

Source: https://oncologyistanbul.com/glossary/metastasis

> The spread of cancer cells from where they first formed to a different part of the body, forming a new tumor there.

Metastasis happens when cancer cells break away from the original (primary) tumor, travel through the bloodstream or lymphatic system, and form a new tumor in another organ or tissue. A metastatic tumor is still named for, and treated based on, where the cancer originated — a breast cancer that has spread to the bone is still breast cancer, not bone cancer. Whether metastasis is present is one of the three factors (alongside tumor size and lymph-node involvement) that TNM staging measures.

## Related
- [TNM staging](https://oncologyistanbul.com/glossary/tnm-staging)

## Authoritative references
- [Wikipedia](https://en.wikipedia.org/wiki/Metastasis)
- [Wikidata](https://www.wikidata.org/wiki/Q181876)

Full glossary: https://oncologyistanbul.com/glossary