Due largely to the explosion of airborne carcinogens resulting from rampant industrialization and development and increased use of fossil fuels, lung cancer has now become the world's leading cause of cancer deaths. Men run the greatest risk of developing the disease, but the number of cases among women is on the rise.
Lung cancer is normally attributed to cigarette smoking, and this indeed is a major risk factor; however, exhaust from fossil fuels such as gasoline, diesel and coal play a part, as does asbestos exposure.
Types of Lung Cancer
Lung cancer may be of the non-small cell type, (NSCLC) or small cell cancer (SCLC). NSCLC is more common, accounting for 75 percent of all lung cancers.
NSCLC has three categories:
- large cell carcinoma
- squamous cell carcinoma.
Adenocarcinoma is the most prevalent, accounting for 40 percent of all NSCLCs. This form of lung cancer stems from abnormal growth of cells that lines the air sacs in the lungs, known as alveoli. Roughly 20 percent of lung cancer cases are of the squamous cell type; also known as epidermoid carcinoma, this form of cancer begins in the thin, flat cells. Large cell carcinoma is relatively rare and can affect any number of cells.
Less common NSCLCs include carcinoid tumor, pleomorphic and salivary gland carcinoma.
Although mesothelioma can affect the respiratory system as well, it has been identified as a separate type of asbestos cancer since 1960. However, mesothelioma lung cancer itself can also result from exposure to asbestos and the chances of developing the disease increase significantly with smoking. Asbestos exposure is one of the main risk factors for developing mesothelioma cancer but can be a factor in lung cancer diagnosis as well.
In addition to cigarette smoking and exposure to burning fossil fuel, risk factors associated with lung cancer include:
- Age and gender (most victims are men over age 40)
- Radon exposure
- Agent Orange (a defoliant used during the Vietnam conflict)
- Nuclear radiation (particularly depleted uranium)
- Second-hand smoke
Fumes from other types of industrial chemicals may also play a part in the development of lung cancer.
Symptoms and Diagnosis
Diagnosing lung cancer can sometimes be difficult, in part, because the symptoms can often mimic those of other respiratory disorders, and typically are not severe during the early stages. These include:
- chest pain
- coughing up blood
- neck and face swelling
- persistent chest, shoulder, or back pain
- frequent bronchitis or pneumonia
Diagnosis begins with a thorough medical and life-style history (including employment) and x-rays. If indications of cancer are seen, the patient will be referred to a specialist, who will run additional tests for protein markers, take more detailed images with computed tomography (CT) and magnetic resonance imaging (MRI) in addition to obtaining tissue samples (biopsy).
Lung cancer patients' prognoses depend on how advanced their cancer is, how or if it has metastasized, and their age and general overall health. Common lung cancer treatments include chemotherapy, radiotherapy or surgery. Some aggressive treatments include a combination of all three.
Once the diagnosis of cancer is confirmed, the oncology team will need to determine how far the cancer has advanced and whether or not it has spread. In the case of SCLC, there are only two stages in which the disease is considered limited or extensive. Most cases of SCLC are treated as advanced because it spreads very aggressively.
Treatment depends on the type of cancer cells that are present in the tumor(s), as well as the different manners in which the cancer metastasizes (spreads) and grows. If the disease is in an early stage, surgery may be the most effective solution; more advanced cases require chemotherapy and radiation treatments, however.
De Llano, Rod. "Symptoms." Lung-Cancer-Web.org.
Staff. "Lung Cancer: Definition." Mayo Clinic.