Mesothelioma is known for its aggressive spread to the rest of the body. While it usually starts on one side of the lung, cancer cells do make its way to the other side of the lung. Here is a closer look at that process.
Metastasis refers to the spread of cancer cells from its original point of development to other parts of the body. As mesothelioma is usually not diagnosed until its later stages, mesothelioma metastasis is usually common at the time of diagnosis. It can also occur as the disease continues to spread.
Where Does Mesothelioma Commonly Spread?
Mesothelioma commonly develops in the chest cavity or the abdominal cavity, affecting vital organs like the lungs and the heart. From there, the cancer can spread to the areas around the lungs, on the side of the body where the original tumor was found.
How Mesothelioma Spreads
The cancer can spread throughout the body in a few ways. Early in the cancer’s development, before metastasis, cancer cells invade nearby healthy tissue through local invasion. When metastasis occurs, cancer cells make their way through the bloodstream or lymphatic system to areas of the body far away from the original location. Once the cells spread, they will be able to invade nearby organs and cause additional tumors to develop.
Mesothelioma can also grow and spread through angiogenesis, a process where new blood vessels in the body are formed. When cancerous cells release molecules that reach healthy tissue, new blood vessels are formed. With a fresh supply of oxygen and nutrients from these blood vessels , cancer cells are able to develop into secondary tumors.
Staging is a way to determine how far the cancer has spread. The treatment and outlook for the cancer largely depends on the stage that the cancer is at, which is derived from the results of physical exams, biopsies and imaging tests like the CT scan or PET scan. A formal staging system only exists for the most common type of cancer, pleural mesothelioma.
The most commonly used system for the growth and spread of pleural mesothelioma is the
AJCC TNM staging system. It’s a system that is based on 3 sources of information, T, which is the extent of spread of the main (primary) tumor, N, the spread of cancer to nearby lymph nodes, and M, whether the cancer has spread or metastasized to other organs of the body. The cancer most commonly spreads to the lung on the other side of the body, and the peritoneum. Lymph nodes are the small, bean-shaped collections of immune system cells, where cancers also spread commonly. Numbers or letters appear after T, N and M to describe each factor. The higher the number, the more advanced the cancer is. These range from T1 – T4, NX – N3, M0 to M1. Once the TNM categories have been assigned, the information is further categorized into stages of I, II, III or IV. The lower the stage number, the better the prognosis.
At Stage I, the cancer has grown in the lining of the chest wall on one side of the chest, which may affect the pleura lining the diaphragm (the breathing muscle) or the mediastinum (the space between the lungs). While it may have spread to the pleura covering the lung, it has neither spread to the lymph nodes nor to distant sites.
At Stage II, mesothelioma has grown into the pleura lining the chest wall on one side of the chest, and also in the pleura coating the diaphragm, the mediastinum and the lung. It has also grown into the diaphragm or the lung itself, but has not spread to the lymph nodes or to distant sites.
Stage III sees the spread of the tumor as far as to the outer lining of the heart, as well as to the lymph nodes in the chest on the same side of the tumor, but not to the opposite side yet.
Stage IV sees the spread of the cancer to the opposite side of the chest, to the heart lining, or into the heart itself, to the lymph nodes, as well as to distant sites.
The cancer spreads to the other side of the lung in the more progressed stages of Stage III and above. Your physician will offer more specific and personalized information on a case-by-case basis. Contact your physician for further information and with any questions you have.