About Liver Tumors

Metastases

What are metastases?

Metastases are cancer cells that have spread beyond the original (primary) cancer site and have established themselves at a distant site. These cancer cells spread through the lymph and vascular (blood vessel) systems involved with the primary cancer site. Metastases generally indicate that cancer cells are widespread within the lymphatic and circulatory systems in the form of "micro metastases", which means that the cancer is in the process of spreading to many areas.

Determining treatment options

The staging system for virtually every primary cancer is unique, identifying the progress of disease for that particular cancer. The stage of the cancer determines the treatment choices. For cancer confined to a specific area, local treatment may be used. Examples of local treatment include excision (surgical removal), or ablation, which means destroying the tumor with radiofrequency (high frequency energy), cryosurgery (freezing), or percutaneous alcohol (alcohol injection), or by blocking the blood supply to the tumor.

Because metastatic cancer has spread, local treatment of the primary cancer will not eliminate the distant sites or the micro metastases that may be involved in the vascular or lymph systems. The presence of distant metastases is, in all cancer staging systems, a symptom of the highest stage of progression. Unfortunately, these high stages are those that respond least well to treatment and have the worst prognosis.

For metastatic cancer, it is necessary to use systemic treatments that travel through the bloodstream and can reach cancer cells throughout the body. Examples of systemic treatments are biological therapy, chemotherapy, and hormone therapy. Metastatic tumors, however, may also require local/excisional treatment if the cancer is accompanied by severe symptoms not resolved by chemotherapy or radiation. This is often seen with neuroendocrine tumors.

Are all liver metastases created equal?

Nearly any primary tumor site can deposit metastases in the liver, since the liver filters blood from throughout the body. Most discussions related to the treatment of metastatic tumors in the liver focus on those originating from primary colorectal cancer sites. In fact, up to 50% of liver metastases are of colorectal cancer origin, while the remainder metastasize from a wide variety of primary cancer sites including sarcomas, breast and kidney, as well as neuroendocrine tumors.

Since the liver is generally the first site of metastatic spread, evidence of metastatic colorectal tumors in the liver does not always mean that the primary cancer has deposited micro metastases in multiple organs. Aggressive surgical intervention while the tumors are limited in number and size and contained within the liver has resulted in reported 25-40% five-year survival rates. Clinical evidence strongly suggests that as the metastatic deposits grow in size and quantity, progression beyond the liver through the circulatory system is inevitable.