Lung cancer is one of the most preventable types of cancer. However, although most lung cancer deaths can be prevented through lifestyle changes, lung cancer kills more people each year than colon, prostate, lymph and breast cancers combined. Lung cancer is always treatable, however, regardless of its size and location, and whether or how far it has spread.
The vast majority of lung cancer is caused by smoking. Smoke is filled with carcinogens that damage the lungs' cells, eventually causing them to behave abnormally. Because the lungs are full of blood vessels, lung cancer can easily spread to other areas of the body, often before any symptoms arise.
Types of Lung Cancer
Based on the cancer cells' appearance, lung cancer is divided into two main types. Although lung cancer can spread anywhere in the body, it usually migrates to other parts of the lungs, and to the lymph nodes, bones, brain, liver and/or adrenal glands. The two main types of lung cancer are:
Non-Small-Cell Lung Cancer (NSCLC)
Non-small-cell lung cancer, which begins in the epithelial cells, is the most common type of lung cancer, accounting for approximately 80 percent of cases. Squamous cell carcinoma, adenocarcinoma and large-cell carcinoma are all subtypes of non-small-cell lung cancer, and all receive the same types of treatment.
Small-Cell Lung Cancer (SCLC)
Small-cell lung cancer is also called oat cell cancer. Approximately 20 percent of lung cancers are small cell. There is a strong correlation between smoking and SCLC, with only one percent of cases diagnosed in nonsmokers. SCLC originates in either the lungs' nerve or hormone-producing cells, and spreads quickly.
Risk Factors for Lung Cancer
The greatest risk factor for developing lung cancer is tobacco-smoking, whether past or present. Approximately 90 percent of lung cancers are linked to tobacco use. Other risk factors for developing lung cancer are listed below but, compared to the risk from smoking, their impact is negligible.
- Exposure to secondhand smoke
- Exposure to asbestos, arsenic, chromium or nickel
- Exposure to radon gas
- Family history of lung cancer
Symptoms of Lung Cancer
In its early stages, lung cancer is usually asymptomatic. As it progresses, symptoms are often the result of blocked breathing passages or of the cancer's spreading within the lungs and to other parts of the body. Symptoms of lung cancer may include:
- Chronic cough
- Coughing up blood
- Shortness of breath
- Constant chest pain
- Loss of appetite or weight loss
Diagnosis of Lung Cancer
Early diagnosis of lung cancer is the best way to achieve a successful outcome, but early diagnosis is rare because symptoms do not usually appear until the disease has progressed. To determine which tests are necessary, a patient's medical history is taken, a physical exam is performed and symptoms are discussed. A diagnosis of lung cancer is usually then confirmed by certain imaging tests and/or types of biopsies. Imaging tests used to help diagnose lung cancer include CT, PET, MRI and bone scans. Types of biopsies used to help diagnose lung cancer include:
- Sputum cytology, in which phlegm is coughed up and examined
- Bronchoscopy, in which a flexible tube removes lung tissue
- Needle aspiration/core biopsy, in which a needle draws out a tissue sample
- Thoracentesis, in which a needle draws out liquid between chest wall and lung
- Thoracotomy, in which a chest incision is made to allow lungs to be examined
- Thoracoscopy, in which a chest incision is made to allow insertion of a camera
- Mediastinoscopy, in which a chest incision is made to collect lymph nodes
Treatment of Lung Cancer
Treatment of lung cancer depends upon the type of lung cancer involved and how far it has progressed. Treatment for non-small-cell lung cancer may include:
- Radiation therapy
- Targeted drug therapy
- Laser therapy
- Photodynamic therapy
- Combination of the above
Treatment for small-cell lung cancer is usually limited to surgery, chemotherapy and radiation therapy, although clinical trials of other types of treatment are ongoing.
Prevention of Lung Cancer
Lung cancer screening on a regular basis is not recommended. Although chest X-rays and CT scans may help detect early-stage lung cancer, they most often detect benign conditions that subject patients to unnecessary invasive testing.
Although there is no sure way to prevent it, the risk of getting lung cancer is greatly reduced with simple lifestyle changes. Not smoking and avoiding secondhand smoke are the best methods of prevention, with those who have never smoked having the lowest risk of developing the disease. Although smokers decrease the likelihood of getting lung cancer by stopping smoking, they will always be at greater risk than those who have never smoked.