It invades surrounding tissue and spreads to nearby or distant organs (metastasis).
The pathologist who evaluates cancer cells in biopsied tissue designates the cancer as being stage I, II, III, or IV, in terms of the degree of metastasis.
Metastasis is very serious in MTC because chemotherapy and radiation therapy are not effective in controlling its spread.
The most common sites in the body where metastasis occurs are the liver and lungs.
"Gene Therapy and Chemotherapy Combine to Stop Breast Cancer and its Metastasis."
Since MTC is slow growing, metastasis may not be obvious.
For example, research in 2003 found that a combination of chemotherapy and gene therapy stopped breast cancer and its metastasis (spread to other organs or parts of the body).
In about 15 percent of cases, physicians find some degree of cancer spread (metastasis).