People Who Die of Cancer Die of Metastatic Disease

Metastatic Cancer

Cancer that has spread from the place where it first started to another place in the body is called metastatic cancer. The process by which cancer cells spread to other parts of the body is called metastasis.

In metastasis, cancer cells break away from where they first formed (primary cancer), 

travel through the blood or lymph system, and form new tumors (metastatic tumors) in other parts of the body. 

The metastatic tumor is the same type of cancer as the primary tumor. National Cancer Institute

Metastatic cancer has the same name and the same type of cancer cells as the original, or primary, cancer. For example, breast cancer that spreads to and forms a metastatic tumor in the lung is metastatic breast cancer, not lung cancer.

Under a microscope, metastatic cancer cells generally look the same as cells of original cancer. Moreover, metastatic cancer cells and cells of original cancer usually have some molecular features in common, such as the presence of specific chromosome changes.

Treatment may help prolong the lives of some people with metastatic cancer. In general, though, the primary goal of treatments for metastatic cancer is to control the growth of cancer or to relieve symptoms caused by it. Metastatic tumors can cause severe damage to how the body functions and most people who die of cancer die of metastatic disease.

source: National Cancer Institute