Stage 4 Non-Small Cell Lung Cancer

Stage 4 non-small cell lung cancer (metastatic lung cancer) is the most advanced stage of lung cancer. Nearly 40% of people newly diagnosed with lung cancer already have stage 4 disease. Stage 4 lung cancer is not curable, but it is treatable, and many clinical trials are in progress looking at new treatments to improve survival. 
Definition of Stage 4 (Metastatic) Non-Small Cell Lung Cancer
Stage 4 non-small cell lung cancer defines a tumor of any size that has spread (metastasized) to another region of the body or to another lobe of the lungs. 
Oncologists use the TNM system to further define stages of lung cancer. A simplified description of the TNM system includes: 

T that refers to tumor size: 

T1 – A tumor is less than 3 cm (1 ½ inches) in size 
T2 –The tumor is greater than 3 cm 
T3 – The tumor can be any size, but is near the airway or has spread to local areas such as the chest wall or diaphragm 
T4 – The tumor is any size, but is located in the airway, or has invaded local structures such as the heart, or the esophagus. A tumor is also considered T4 if cancer cells are present in the space between the layers lining the lungs (malignant pleural effusion).
N refers to lymph nodes: 

N0 – No nodes are affected 
N1 – The tumor has spread to nearby nodes on the same side of the body 
N2 – The tumor has spread to nodes further away but on the same side of the body 
N3 – Cancer cells are present in lymph nodes on the other side of the chest from the tumor, or in nodes near the collarbone or neck muscles
M represents metastatic disease: 

M0 – No metastases are present M1 – The tumor has spread (metastasized) to other regions of the body or the other lung
Using the TNM system, stage 4 lung cancer is described as: 

T (any), N (any), M1 – Meaning a tumor of any size, with or without nodes, that has metastasized (spread) to another lobe of the lung or to a distant region of the body
Symptoms of Stage 4 (Metastatic) Non-Small Cell Lung Cancer
Symptoms of stage 4 lung cancer may include 
Symptoms due to the presence of a tumor in the lungs such as: 

Persistent cough 
Coughing up blood (hemptysis) 
Shortness of breath 
Pain the chest, back or arms 
Repeated episodes of pneumonia or bronchitis 
Symptoms due to spread of the tumor to other regions of the body, for example: 

Pain in the back, hips, or ribs if the tumor has spread to bone 
Difficulty swallowing due to a tumor being near or invading the esophagus 
Headaches, vision changes, weakness, or seizures if a tumor spreads to the brain
And symptoms related to metastatic cancer in general: 

Weight loss 
Loss of appetite
Treatment of Stage 4 (Metastatic) Non-Small Cell Lung Cancer
Because stage 4 lung cancer has spread beyond the lungs it is considered inoperable, that is, surgery would be unable to remove all of the tumor and offer a chance for a cure. But stage 4 lung cancer is treatable. In those that are able to tolerate chemotherapy, both traditional chemotherapy and/or the newer targeted therapies may improve survival and help with the symptoms of lung cancer. Many clinical trials are in progress looking at combinations of chemotherapy and targeted therapies. 
Radiation therapy may be recommended as a palliative therapy –- therapy that is done to control symptoms but does not result in a cure. This can be helpful for some people to control bone pain (due to tumors spreading to bone), bleeding from the lungs, tumors that are obstructing the airways and causing shortness of breath, or brain metastases that are causing significant symptoms, such as headaches or weakness. 

It is important to discuss any treatment you are considering with your doctor and your loved ones, so you can carefully weigh the risks and benefits of treatment. 

Prognosis With Stage 4 (Metastatic) Non-Small Cell Lung Cancer
The overall 5-year survival rate for stage 4 lung cancer is sadly less than 10%. The median survival time (time at which 50% of patients are alive and 50% have passed away) is about 8 months. 
What Can I Do to Help Myself With Stage 4 Lung Cancer?
Studies suggest that learning what you can about your lung cancer can improve your quality of life, and possibly even your outcome. Ask questions. Learn about clinical trials. Consider joining a support group. Many of us hesitate to talk about end-of-life issues, but discussing these with your doctor and your family –- even if all of you are hoping for a cure –- is associated with fewer feelings of loneliness and a better quality of life. Never lose hope, even if you have chosen not to pursue further treatment. Hope for quality time with loved ones, with good control of your symptoms. Hope for the future of your loved ones who will remain, with memories of you in their hearts. 

Faithi, A. and J. Brahmer. Chemotherapy for advanced stage non-small cell lung cancer. Seminars in Thoracic and Cardiovascular Surgery. 2008. 20(3):210-6.