Lung Cancer
Although one of the most preventable types of cancer, lung cancer kills more people each year than colon, prostate, lymph and breast cancers combined. Lung cancer is always treatable, however, regardless of whether or how far it has spread.
Most lung cancer deaths can be prevented through lifestyle changes, including stopping 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 symptoms arise. The vast majority of lung cancer is caused by smoking.
Types of Lung Cancer
Based on the cancer cells' appearance, lung cancer is divided into two main types.
Non-Small-Cell Lung Cancer (NSCLC)
NSCLC, 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 NSCLC, and all receive the same types of treatment.
Small-Cell Lung Cancer (SCLC)
SCLC is also called oat cell cancer. Approximately 20 percent of lung cancers are small cell. There is a strong correlation between smoking and SCLC; nonsmokers account for only one percent of SCLC cases. SCLC originates in either the lungs' nerve or hormone-producing cells, and spreads quickly.
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.
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 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
Having a family history of lung cancer also increases the risk of its developing.
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 the cancer's spreading within the lungs and to other parts of the body. Symptoms of lung cancer include the following:
- Chronic cough
- Coughing up blood
- Shortness of breath
- Wheezing
- Hoarseness
- Constant chest pain
A loss of appetite and/or weight can also be symptoms of lung cancer.
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 cancer 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. Types of biopsies used to help diagnose lung cancer include those below:
- Sputum cytology (phlegm is coughed up and examined)
- Bronchoscopy (a flexible tube is used to remove lung tissue)
- Needle aspiration/core biopsy (a needle is used to draw out a tissue sample)
- Thoracentesis (a needle is used to draw out liquid between chest wall and lung)
- Thoracotomy (a chest incision is made so lungs can be examined)
- Thoracoscopy (a chest incision is made to allow a camera to be inserted)
- Mediastinoscopy (a chest incision is made so lymph nodes can be collected)
Imaging tests used to help diagnose lung cancer include CT, PET, MRI and bone scans.
Treatment of Lung Cancer
Treatment of lung cancer depends upon the type involved, and how far it has progressed. Treatment for NSCLC includes the following:
- Surgery
- Radiation therapy
- Chemotherapy
- Targeted drug therapy
- Laser therapy
- Photodynamic therapy
- Combination of the above
Treatment for SCLC 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 to 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; those who have never smoked have the lowest risk of developing lung cancer. Although smokers decrease their likelihood of getting lung cancer by stopping smoking, they will always be at greater risk than those who have never smoked.