Excluding skin cancer, lung cancer has been the most common cancer in the world for several decades. It is also the most common cause of death from cancer.
The likelihood of developing lung cancer increases significantly with age, with research from the American Cancer Society showing that approximately 2 out of 3 people diagnosed are 65 years or older. Despite the very serious prognosis of lung cancer, some people with earlier stage cancers can be cured.
Read on to find out more about the causes, types and symptoms of this disease. Prevention is key when it comes to lung cancer, so included are some pointers to help you prevent this cancer.
If you are concerned that you might have lung cancer, there is information about the diagnostic tests your doctor might conduct, as well as the treatment options available.
Typically, there are no signs or symptoms in the earliest stages of lung cancer. Once it develops, most people with lung cancer have one or more of these symptoms:
If the cancer has spread beyond the lungs, it can cause other symptoms such as bone pain if it has spread to your bones.
Many of these warning signs can also be caused by other conditions. See your doctor if you have symptoms so that the cause of your problem can be found, diagnosed and properly treated.
Lung cancer is a type of cancer that starts in the lungs. Your lungs are 2 sponge-like organs found in your chest that essentially take in oxygen when you inhale and release carbon dioxide when you exhale.
Lung cancers almost always start in the cells lining the bronchi – the tubular, branching airways of the lungs. They are thought to initially produce pre-cancerous changes in the lung, but over time the abnormal cells acquire other gene changes, which cause them to progress to true cancer.
At some point, cells from the cancer may break away from the original tumor and spread (metastasise) to other parts of the body, including the liver, bones, adrenal glands and brain. Lung cancer is often a life-threatening disease because it tends to spread in this way even before it can be detected on an imaging test such as a chest x-ray.
There are more than 20 identified types of cancerous tumors that originate in the lung itself. However, lung cancers are divided into two main types, based on how their cells look under the microscope: non-small cell lung cancer and small cell lung cancer.
Non-small cell lung cancer may be localised, which means that it is limited to the lung or that it hasn't spread beyond the chest. Small cell lung cancer is rarely localised, even when it is detected early. Knowing whether the cancer has spread is critical, because it affects treatment decisions. See the section Types of Lung Cancer for more information.
Smoking causes the majority of lung cancers — both in smokers and in those exposed to second-hand smoke. However, more and more lung cancers are being diagnosed in people who have never smoked.
Medical experts at Mayo Clinic believe smoking causes lung cancer by damaging the cells that line the lungs. Inhaling cigarette smoke, which is full of cancer-causing substances (carcinogens), causes changes in the lung tissue to take place almost immediately. At first your body may be able to repair this damage, but with repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and to eventually develop into cancer.
Lung cancer in non-smokers can be caused by exposure to radon, secondhand smoke, air pollution, or other factors. Workplace exposures to asbestos or certain other chemicals can also cause lung cancers in some people who do not smoke.
There are 2 main types of lung cancer: small cell lung cancer and non-small cell lung cancer.
Based on your symptoms and risk factors, such as your smoking history and exposure to cancer-causing agents, your doctor may order a number of tests to look for cancerous cells. In order to diagnose lung cancer, he or she may recommend any of the below tests.
Stages of lung cancer
Once your lung cancer has been diagnosed, your doctor will often run further tests to determine the stage of your cancer. Staging tests may include imaging procedures such as CT scans, magnetic resonance imaging (MRI), positron emission tomography (PET) and bone scans. Knowing the type of cancer and its stage helps you and your doctor decide what treatment is most appropriate.
The stages for lung cancer are:
In addition, small cell lung cancers are sometimes divided into 2 groups: limited or extensive. Limited means the cancer involves only one lung and the nearby lymph nodes, while extensive indicates cancer has spread beyond the one lung to other areas of the chest or to distant organs.
Once lung cancer has been diagnosed, treatment depends on the type and stage of cancer. Options typically involve one or more treatments including surgery, chemotherapy, radiation therapy or targeted drug therapy. Surgery is the main treatment for non-small cell lung cancers that have not spread beyond the chest. There are three types of surgery:
If you undergo surgery, your surgeon may also remove lymph nodes from your chest to check if the cancer has spread. Lung cancer surgery carries risks, including bleeding and infection. Because surgery will remove part or all of a lung, breathing may also be more difficult afterwards.
Not all lung cancers can be prevented, however you can reduce your risk if you: