Adenocarcinomas are often found in an outer area of the lung.
Squamous cell carcinomas are usually found in the center of the lung next to an air tube (bronchus).
Large cell carcinomas can occur in any part of the lung. They tend to grow and spread faster than the other two types.
Causes, incidence, and risk factors
Smoking causes most cases of lung cancer. The risk depends on the number of cigarettes you smoke every day and for how long you have smoked. Being around the smoke from other people (secondhand smoke) also raises your risk for lung cancer. However, some people who do not smoke and have never smoked develop lung cancer.
Research shows that smoking marijuana may help cancer cells grow, but there is no direct link between the drug and developing lung cancer.
High levels of air pollution and drinking water containing high levels of arsenic can increase your risk for lung cancer. A history of radiation therapy to the lungs can also increase the risk.
Working with or near the following cancer-causing chemicals or materials can also increase your risk:
Chemicals such as uranium, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, and diesel exhaust
Certain alloys, paints, pigments, and preservatives
Products using chloride and formaldehyde
Early lung cancer may not cause any symptoms. Symptoms you should watch for include:
If the biopsy shows that you do have lung cancer, more imaging tests will be done to determine the stage of the cancer. Stage means how big the tumor is and how far it has spread. Non-small cell lung cancer is divided into five stages:
Stage 0 - the cancer has not spread beyond the inner lining of the lung
Stage I - the cancer is small and hasn't spread to the lymph nodes
Stage II - the cancer has spread to some lymph nodes near the original tumor
Stage III - the cancer has spread to nearby tissue or to far away lymph nodes
Stage IV - the cancer has spread to other organs of the body, such as the other lung, brain, or liver
There are many different types of treatment for non-small cell lung cancer. Treatment depends on the stage of the cancer.
Surgery is the often the treatment for patients with non-small cell lung cancer that has not spread beyond nearby lymph nodes. The surgeon may remove:
One of the lobes of the lung (lobectomy)
Only a small part of the lung (wedge or segment removal)
The entire lung (pneumonectomy)
Some patients need chemotherapy. Chemotherapy uses drugs to kill cancer cells and stop new cells from growing.
Chemotherapy alone is often used when the cancer has spread outside the lung (stage IV).
It may also be given before surgery or radiation to make those treatments more effective. This is called neoadjuvant therapy.
It may be given after surgery to kill any remaining cancer. This is called adjuvant therapy.
The outlook varies widely. Most often, NSCLC grows slowly. The cancer may spread to other parts of the body, including the bone, liver, small intestine, and brain.
However, in some cases, it can be very aggressive and cause rapid death. Chemotherapy has been shown to prolong the life and improve the quality of life in some patients with stage IV NSCLC.
Cure rates are related to the stage of disease and whether you are able to have surgery.
Stage I and II cancers have the highest survival and cure rates.
Stage III tumors can be cured in some cases.
Patients with stage IV disease or cancer that has returned are almost never cured. The goals of therapy are to extend and improve their quality of life.
Spread of disease beyond the lung
Side effects of surgery, chemotherapy, or radiation therapy
If you smoke, stop smoking. It's never too late to quit. Your risk of lung cancer drops dramatically the first year after you quit. Stopping even after you've been diagnosed with early-stage lung cancer may improve your outlook.
Also avoid breathing in the smoke from other people's cigarettes, cigars, or pipes.
Routine lung cancer screening using chest x-ray or lung CT scan is not currently recommended for people who don't have symptoms. Many studies have been done to test the benefit of screening. Most experts have concluded that screening will not cure the disease or help people live longer. Screening may lead to many unneeded biopsies or surgeries.
The long-term use of vitamin C, vitamin E, and folate does not seem to reduce the risk of lung cancer.
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Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.