Lung Cancer and Thoracic Cancers

Lung cancer, or primary lung cancer, refers to cancer cells that develop in the lungs or in the airways within the lungs known as the bronchi.

Localized lung cancer is limited to the lung tissues and airways. Metastatic lung cancer is lung cancer that has spread beyond the lung tissue and airways to other organs within the body.

A cancer that started in a different part of your body and spreads to your lungs is called lung metastasis. Cancers that more commonly spread to the lung include breast, colorectal, head and neck, kidney, testicular, uterine, and muscle and soft tissue cancers.

Lung Cancer Causes

Many factors affect whether or not a person may develop lung cancer. Some people get lung cancer due to gene mutations (changes) over long periods of time. These are called somatic mutations, and they make it more likely for cells to grow out of control and form tumors. Mutations damage the DNA in cells, which keeps cells from repairing themselves. The most common mutations found in people who develop lung cancer affect specific genes: ALK, TP53, EGFR and KRAS.

Having a family history of lung cancer is possible but it is not common. Inherited gene mutations account for only about 8% of lung cancer cases. If you have multiple first-degree relatives who have had lung cancer, talk with your doctor to find out if genetic testing and lung cancer risk reduction strategies are right for you.

Lung Cancer Risk Factors and Prevention

Know your risk factors. If you think you might be at a higher risk for developing lung cancer, talk to your doctor about what you can do to reduce your risk.

If you are a heavy smoker or were a heavy smoker in the past and are between the ages of 50 and 77, talk with your doctor about lung cancer screening. Annual CT screening can find lung nodules, lung disease, heart conditions or early lung cancers that can be treated successfully.

Lung cancer risk factors include: 

• Smoking cigarettes and using other tobacco products: Smoking cigarettes is responsible for 80% to 90% of lung cancer cases; however, many smokers do not develop lung cancer. It depends on how long a person has smoked and how much they smoke every day. Other tobacco products, like cigars and pipes, also cause lung cancer. Substances in tobacco cause lung and other cancers by changing the DNA of cells and causing inflammation in the cells of lung and airway tissues, which can lead to lung cancer.
  • Don’t smoke. If you smoke now, quit smoking. This includes vaping and e-cigarettes, which are not safe alternatives to smoking cigarettes. Talk with your doctor to get help with a quit-smoking plan.
• Exposure to second hand smoke: People who have never smoked can get lung cancer, too. Sometimes, it is from second hand smoke. Keep your children and other family members away from smoke and smoking materials.
• Exposure to environmental toxins: Radon gas, asbestos and other cancer-causing toxins are highly toxic. These substances are found in the home, in flooring, cement, electrical insulation and hazardous materials common in construction, painting and other occupations.
  • Have your home tested for radon. Radon is a radioactive gas found in the atmosphere. It can get into your home through ventilation systems or cracks. You can’t see it, smell it or taste it, but it is harmful. If radon is present, install a system to reduce radon build-up by expelling it into the air above your roof.
  • Protect yourself in the workplace. Be sure to use all the protection, such as clothing, masks and other equipment, available in the workplace to reduce your exposure to carcinogens. Keep up with training on risk reduction provided to you by your employer.
• Chronic lung disease: A history of certain types of chronic lung disease, such as bronchitis, emphysema, pneumonia and tuberculosis, can increase your risk. Although the relationship between previous lung disease and lung cancer is not completely understood, inflammation from chronic lung disease may contribute to a higher risk of developing lung cancer.
• HIV infection: Having the infection responsible for acquired immunodeficiency syndrome (AIDS) is a risk factor for lung cancer, although it may be because people who have HIV smoke more than people who aren’t infected. It is not clear if the HIV infection, having HIV and also being exposed to tobacco smoke raise the risk of getting lung cancer.
• Taking high daily doses of beta-carotene supplements (20 mg.): Beta-carotene changes to vitamin A in the body. Rarely, people may need to take beta-carotene supplements if they have been diagnosed with night blindness, certain eye or skin problems or slowed growth related to a lack of vitamin A. If you are a heavy smoker or have been exposed to asbestos and have been prescribed beta-carotene supplements, tell your doctor before you start taking them. These supplements can increase your risk of developing lung cancer.

Lung Cancer Symptoms

Lung cancer does not always cause symptoms in the early stages. Sometimes, symptoms don’t appear until it is more advanced. The following symptoms could indicate lung cancer and should be discussed with your doctor.

• A new cough, a cough that does not go away or one that gets worse over time
• Dull, aching, persistent chest pain
• Coughing up blood
• Shortness of breath
• Recurring lung infections
• Wheezing or hoarseness
• Unexplained weight loss
• Loss of appetite

Types of Lung Cancer

The main types of primary lung cancer are non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common type, representing around 80% to 85% of all lung cancers. There are several subtypes of NSCLC (named for the types of cells affected by the cancer):

• Adenocarcinoma: Starts in cells lining the alveoli. Oxygen passes through these little air sacs after being inhaled. It then moves through the bloodstream to other tissues in the body. Adenocarcinoma lung cancers are usually further classified by molecular markers.
• Large-cell carcinoma: Also called epidermoid carcinoma, it begins in large cells found in the lung tissues.
• Squamous cell carcinoma: Forms in flat cells lining the inside of the lungs.

Other types of NSCLC (less common) include the following.

• Adenosquamous carcinoma: Cancer that contains two cell types – squamous cells and gland-like cells
• Carcinoid tumor: Slow-growing cancer that can develop in the lungs but is usually found in the GI system.
• Sarcomatoid carcinoma: Has cells that resemble several types of cells, including carcinoma and sarcoma.

Small-Cell Lung Cancer

Small-cell lung cancer, representing 10% or 15% of lung cancers. It is considered a neuroendocrine cancer that can grow and spread faster than NSCLC. Often, by the time it is found, it has already spread beyond the lungs.

Pleural Mesothelioma

Pleural mesothelioma, also known as thoracic mesothelioma, is a cancer that arises in the thin lining that surrounds the lungs. This membrane is the mesothelium, a layer of tissue that lines many of the body’s internal organs. The part of the mesothelium that protects the lungs is called the pleura, which is why this cancer is known as pleural mesothelioma.