Determining Lung Cancer Stage
The lung cancer stage defines the extent, prognosis and treatment of the disease. The more advanced the cancer, the harder it will be to remove it from the body. Early and late stage patients are generally subjected to any combination of surgery, chemotherapy or radiation therapy. The length and intensity of these methods is what changes as staging progresses.
Doctors perform diagnostic imaging and take biopsy samples to study each patient’s cancerous cells. Through computed tomography (CT scans), chest x-rays and magnetic resonance imaging the exact location and size of a tumor can be found. Diagnostics should also show any spreading to other areas of the body. The ‘TNM’ system is used to describe the results.
T is for tumor size, and is graded from T1-T4. Smaller tumors are assigned a rating of 1a-1b, and are 3 centimeters across or less. A T2 is from 3 to 7 centimeters across and is invading the main bronchus or the visceral pleura (chest cavity inner lining.) A T3 is larger than 7 centimeters and has grown into the chest wall, the chest cavity lining, the diaphragm or the pericardium surrounding the heart.
A T4 may have infiltrated any of the previous areas. In addition, the airways, main blood vessels, bones or lymphatic system above the collarbone can be infected.
N indicates whether the lymph nodes have been infected by the cancer. An assessment graded N0 means they are not. N1, N2 or N3 indicate the disease is no longer localized. It is now using the lymphatic system to travel throughout the body. An N1 or N2 means it is contained in the infected chest area lymph nodes. N3 communicates that the growth has moved to the opposite side of the chest.
M stands for metastasis. Cancers spread through the lymphatic system and in the blood, a process called metastasis. When the disease takes root at a location distant to the origin, it is harder to remove from the patient. An M0 is used when there is no evident metastasis. An M1 or 1a shows it has metastasized locally. A grade of M1b is for malignant cells distant to the original infected area, such as the bones or liver.
Based on the findings of the TNM system, a cancer stage is assigned.