The lungs are organs essential to respiration. Both lungs are located in the chest cavity of an individual, and transport oxygen from the environment into the blood stream. Lungs provide the body, not only with essential oxygen, but also remove carbon dioxide from the bloodstream into the atmosphere. 

What is Lung Cancer?

Lung cancer, then, is the uncontrolled growth of cancerous cells beginning in the lungs. While normal lung tissue serve a natural function and produce a specific shape, cancerous lung cells grow rapidly with no regard to the natural function or shape of the lung. These cells, growing and reproducing quickly, form tumors that impede the normal functioning of a lung. In the United States, lung cancer is the leading killer of all cancers, more than many of the most common cancers combined (including breast, colon, and skin cancers). This high mortality rate is due to the large size of the lungs, and the generally asymptomatic nature of the disease. These statistics show that even though lung cancer is not the most common form of cancer, it is indeed the most deadly.

Types of Lung Cancer

There are two main types of lung cancer: non-small cell lung cancer and small cell lung cancer. As the names suggest, the type of cancer is determined by the type of cells that the cancer affects. 

·         Small cell lung cancer, also known as oat cell cancer (due to the small size and round shape of the cells), accounts for approximately 15% of all lung cancers. This type of lung cancer is especially dangerous, growing quickly into large tumors and spreading quickly to other parts of the lung and to distant areas. The disease affects men more than women and almost always develops as a result of cigarette smoking. Small cell lung cancer, due to its aggressive nature, is almost always diagnosed at an advanced stage. Furthermore, surgery is not generally an option for the treatment of small cell lung cancer. Chemotherapy, sometimes along with radiation, is the treatment of choice.

·         Non-small cell lung cancer represents the overwhelming majority of lung cancers. There are three main type of non-small cell lung cancer: squamous cell carcinoma, adenocarcinoma, and large-cell undifferentiated carcinoma.  Each of these types of non-small cell lung cancer have unique characteristics, differing in size, shape, and chemical make-up.

Causes of Lung Cancer

There are a number of different factors that can be pointed to as causes of lung cancer. However, as with other forms of cancer, there is no direct cause of lung cancer -- only risk factors. The greatest risk factor associated with lung cancer is cigarette smoke. Smoking cigarettes, as well as smoking pipes and tobacco, greatly increases an individual's risk for developing lung cancer. Even non-smokers can be at risk for developing lung cancer, as nearly 20 percent of all lung cancer cases occur in non-smoking individuals.

Other risk factors associated with lung cancer include secondhand smoke, asbestos fibers, radon gas, family history, and air pollution. The minute silicate fibers of asbestos can infect an individual's lung tissue for an entire lifetime.  Radon case, a byproduct of uranium, causes approximately 12% of lung cancer deaths. Approximately 6% of lung cancer deaths were a result of family history with the disease, while only 1% of lung cancer deaths were attributed to air pollution in the United States.

Prevention

There is currently no way to prevent the development of lung cancer. However, one can reduce his or her risk factors associated with lung cancer, effectively reducing the likelihood of developing the disease. The first and most obvious measure that can be taken to prevent lung cancer is to quit smoking. By quitting smoking, an individual reduces his or her risk of lung cancer by 25%, even if it takes 15 years to achieve the healthy lungs of a non-smoker.  Furthermore, avoiding asbestos fibers, radon gas, and secondhand smoke will reduce the risk of lung cancer.

Symptoms and Signs

Lung cancer may cause a number of different symptoms. The most common symptom of lung cancer is a hacking cough, as a tumor may grow to block an air passage. Other symptoms include:

·         Chest pain or back pain

·         Shortness of breath

·         Fatigue and tiredness

·         Repeated pneumonia or bronchitis as a result of the growing tumor

·         Swelling of the neck and face

Furthermore, if the lung cancer metastasizes to another part of the body, symptoms may appear in the cancerous region. For example, if the cancer has spread to the bone, the patient may feel bone pain. If the cancer has spread to the spinal chord, the patient may experience paralysis. This type of lung cancer is at its advanced stage, and becomes difficult to treat.

Screening

Lung cancer screening has been a topic of debate, as experts have not found sound evidence that screening for early detection reduces an individual's mortality. As such, experts do not recommend or discourage individuals to be screened for lung cancer. Today, there are a number of clinical trials aimed at testing the efficacy of lung cancer screening, but results are still pending.

Diagnosis and Tests

If an individual and his or her doctor determine that lung cancer may be present, the doctor will conduct a number of different tests in hopes of reaching a diagnosis. Each test will seek cancerous cells and rule out other possible conditions. Some of the most common tests used for lung cancer diagnosis include:

·         Image testing such has a chest x-ray or CT scan. These imaging tests allow the doctor to reveal abnormal masses in the lungs.

·         Sputum cytology involves the analysis of a sample of sputum from the lungs, looking for any evidence of cancer cells.

·         Biopsy of the lungs is almost always required and involves the removal of a small sample of abnormal cells. This sample is then studied for cancerous cells. There are a few different ways to obtain a lung biopsy: a bronchoscopy, mediastinoscopy, and needle biopsy are all possible options.

Staging

After an individual has been diagnosed, the doctor will stage the cancer. Depending on the stage of the cancer, the prognosis and treatment of the patient will vary. In the staging of lung cancer, doctors usually use the TNM system, in which the T describes the size of the tumor; the N describes the regional lymph nodes; and the M describes the metastases of the cancer. The cancer is then staged from stage 0 to stage IV. In stage 0, there is no evidence of the cancer. By the time the cancer reaches stage IV, it has already spread to distant areas of the body.

Prognosis

Many different factors determine the prognosis of a lung cancer patient. The most important factor in determining a patient's prognosis is the staging of the cancer. As expected, the more advanced the stage, the poorer the prognosis will be. Generally speaking, the prognosis for lung cancer patients is poor, with fewer than 10% of people alive 5 years after diagnosis. 

Treatment

Treatment for lung cancer has improved drastically in recent years. Today, patients and doctors can choose from a variety of different options that extend beyond the traditional chemotherapy or surgery. There are generally two types of treatment: curative and palliative. Curative treatment aims to remove cancerous cells, while palliative treatment aims to reduce pain and suffering associated with symptoms of lung cancer. Some of the most effective treatments for lung cancer include:

·         Surgery - while surgery is not generally used in the treatment of lung cancer, it may be utilized in the early stages. About 10-35% of lung cancer can be removed surgically, but the procedure does not always guarantee a cure.  The 5 year survival rate of lung cancer surgery is 25-40%.

·         Radiation therapy - radiation therapy can be used in both early and advanced stages of lung cancer. The actual procedure of radiation therapy involves the use of high-energy X-rays to destroy cancer cells. Radiation therapy is most often used as adjuvant therapy to chemotherapy or as post-surgery treatment.

·         Chemotherapy- chemotherapy uses anti-cancer drugs to destroy cancer drugs. Chemotherapy is the main treatment for people suffering from small cell lung cancer. This type of treatment is usually used along with another form of treatment.

·         Target therapy - target therapy hones in on cancerous cells, presenting little or no damage to surrounding healthy cells. Using the medicine Erlotinib, doctors can separate cancerous cells from healthy cells and target the cancerous cells.

·         Radiofrequency Ablation - this type of therapy has been implemented as a replacement to surgery. In this treatment, radiofrequency energy is transmitted through the tip of a needle and inserted into the cancerous area. This treatment has proved to show greater chance for survival and reduce recovery time.