Metastatic Disease: The Wandering Cancer

Finding out that one has cancer is a devastating event, one that is compounded upon the further discovery that the disease has metastasized.  Metastatic disease refers to the spread of cancerous cells from an original tumor to other tissues or organs.  This migration happens when the original tumor leaks or ruptures, releasing cancerous cells into neighboring tissues or organs, or into the lymphatic or circulatory systems.

When that migration occurs, the secondary tumor, known as a metastatic tumor, retains the cellular characteristics of the tumor from which the cancerous cells were released: the metastatic tumor is the “child” of the “parent” primary tumor.  For example, if the cancer originates in the colon and subsequently spreads to the liver, the metastatic tumor would have the cellular characteristics of the original tumor in the colon, not the cellular characteristics of the liver.

In many cases of metastatic disease, the formation of new tumors takes place in the lungs when cancerous cells have entered the bloodstream.  The constant cycle of deoxygenated blood returning to the lungs to become oxygenated brings the cancerous cells into intimate contact with lung tissue.  Many intestinal cancers, however, migrate to the liver.  Blood carrying cancerous cells first encounters the liver, for filtration and detoxification, and the cancerous cells find a suitable location for development of the metastatic tumor.

Metastatic disease is commonly seen in advanced cases of cancer.  While treatment modalities for early stage cancers might be very aggressive, i.e., a combination of surgery, radiation therapy and chemo therapy, with the goal to cure the disease, the treatment goal for metastatic disease is often to not make the disease worse.  Lower dose chemotherapy, delivered more frequently, may be more appropriate to maintain a better quality of life for the patient.