Types of Lung Cancer

Lung cancer is divided into two general categories, small cell lung cancer and non-small cell lung cancer. Each variation of the disease may have different symptoms and different treatments. Eight of every ten cases of lung cancer will be non-small cell lung cancer.

Non-small cell lung cancer

Non-small cell lung cancer exists when malignant cells form in the tissue of the lungs. Affected areas can include the lungs themselves as well as the bronchi, the tubes that send air from the windpipes to the lungs. The main cause of non-small cell lung cancer has been shown to be cigarette smoking or other tabacco usage but additional risk factors such as exposure to certain chemicals or environmental hazards also exist.

Non-small cell lung cancer can be divided into three main types. They are large cell lung cancer, squamous cell lung cancer and adenocarcinoma of the lung. Each variety of the disease has cells that are different in their size, shape and chemical composition.

Large cell lung cancer

Abnormal cells in the lungs that grow and spread uncontrollably categorize large cell carcinoma. Approximately 10% of all lung cancers are this type and it is known to spread rapidly making it the hardest lung cancer to treat.

Large cell carcinoma was named for the large size of the cells when viewed under a microscope, however the tumors associated with this illness are also commonly large when first discovered. These tumors are often initially detected by chest x-ray and can start anywhere within the lung.

Patients suffering from large cell lung cancer may experience a variety of symptoms. These include shortness of breath, chest pain, weight loss, and hemoptysis (coughing up blood). There are additional symptoms associated with this illness although some individuals will encounter no symptoms at all until the disease is very advanced. Patients with large cell lung cancer may be faced with an unusual side effect of the disease called paraneoplastic phenomenon. This describes a situation in which a chemical secretion from the cancer can cause enlargement of the breasts in male patients.

Treatment of large cell lung cancer is most often determined once the stage of the disease has been discovered. Stage refers to the location and size of the tumor. If the tumor is small and has not spread to any of the surrounding tissue the cancer is in Stage I. Stage II and III describe tumors that have invaded other tissue and organs within the chest cavity. Stage IV cancer has spread outside the chest cavity and is the most serious stage of the disease. At this stage lung cancer is difficult to treat.

The most common treatments for large cell lung cancer are surgery, chemotherapy treatments and radiation therapy. Surgery is performed when tumors are small and localized. As the tumors grow and spread surgery may not be an option and chemotherapy and radiation therapy may be used to treat the symptoms of the disease. In most cases a combination of these three treatment types is used to most effectively treat the disease.

The prognosis for large cell carcinoma varies depending on the stage of the disease when diagnosed and treated. Earlier stages of the disease have a much greater 5-year survival rate (50%) than those in later stages (8%). The overall average 5-year survival rate is 16%.

Squamous cell lung cancer

Squamous cell lung cancer is another form of non-small cell lung cancer. It is categorized by the shape and location of the cells affected. Squamous cells resemble the scales of a fish and line the hollow organs of the body as well as the passages of the respiratory and digestive systems. Squamous cell carcinoma makes up over 25% of all lung cancers. It is closely associated with smoking and often occurs in the bronchial passages.

The symptoms associated with squamous cell lung cancer are similar to those that patients experience with any lung cancer including, shortness of breath, pain in the chest and weight loss. However, due to the location of the tumors in squamous cell carcinoma (in the center of the lungs) patients may begin to experience hemotypsis (coughing up blood) much earlier.

Bodily fluids can carry cancer cells to other areas of the body and this often occurs in squamous cell carcinoma due to the constant flow of fluid through the lungs. Unless this illness is diagnosed at an early stage it can rapidly spread throughout the body.

Squamous cell carcinoma is usually first detected by a chest x-ray. Additional imaging tests are then done to determine the size, shape and location of the tumor. Additional tests are also performed so doctors can be sure of the type and stage of the cancer. These may include a thoracentesis, needle biopsy or bronchoscopy.

Treatment of this type of non-small cell lung cancer, like the others, will depend largely on the stage of the disease when it is diagnosed. Surgery will often be done on tumors that are localized and small in size. Chemotherapy and radiation therapy will usually be administered after surgery to prevent further spread of the disease or they will be give to relieve symptoms in more advanced cancer cases.

Prognosis for squamous cell lung cancer is approximately the same as large cell lung cancer. The overall survival rate after 5 years is 16%. However, if found at an early stage treatment is much more effective.

Adenocarcinoma of the lung

Adenocarcinoma of the lung usually occurs on the outer part of the lung. The cells that make up this type of cancer are flat and look like skin when viewed under a microscope. This type of non-small cell lung cancer is the most common of all lung cancers and makes up approximately 40% of all cases.

Adenocarcinoma of the lung is directly related to smoking although it also has the highest frequency of occurrence in non-smokers. Environmental factors such as second-hand smoke or chemical exposure can sometimes be the cause. This type of lung cancer has shown the best response to radiation therapy and surgical treatments, possibly because the tumors are often localized (have not spread).

As with other the other non-small cell lung cancers patients may experience chest pain, persistent cough and hemotypsis. Some patients do remain asymptomatic (having no symptoms).

To identify this disease doctors will perform a chest x-ray and then complete additional tests to determine the stage and type. Some of these tests include a biopsy, thoracentesis, and CT scan. These will help to confirm the diagnosis of adenocarcinoma of the lung.

Treatment, as with all non-small cell lung cancers, is decided upon after stage is determined. The treatment options are the same as in most lung cancer cases, surgery, chemotherapy or radiation therapy. Most often a combination of these treatments is used. The types of surgical procedures a doctor may perform are wedge resection (removal of small portion of lung), lobectomy (removal of one lobe of the lung) or pneumonectomy (removal of an entire lung).

Prognosis of patients with adenocarcinoma of the lung is approximately 17% survival for patients after 5 years.

Prevention

Although all lung cancer cannot be prevented, tobacco usage of any kind is a known risk factor for this disease as is exposure to asbestos. Not smoking, quitting a current smoking habit, and avoiding asbestos dust are the best defenses against lung cancer. Many clinical trials are underway in the hopes of developing new treatments for this disease.