Lung Cancer Disease

What is Lung Cancer?



Also called: Bronchogenic carcinoma

Lung cancer is a malignant (cancerous) tumor that starts from cells of the lung.

The lungs are a pair of sponge-like organs found in the chest that take in oxygen when we breathe in and get rid of carbon dioxide when we breathe out. The right lung is a bit larger than the left lung, which is smaller to accommodate for the size of the heart on the left side of the body. The right lung has three sections, called lobes, and the left lung has two.

Lung cancer is the rapid growth of abnormal cells in the lung. It can start anywhere in the lungs and affect any part of the respiratory system.

Lung cancer is the leading cause of cancer deaths in both men and women. Fewer than half of the people who develop lung cancer live 1 more year. And only 15% of people who develop lung cancer live for 5 more years.

Type of Lung Cancer



Lung cancer is commonly divided into two types:

1. Small Cell Lung Cancer (SCLC). Small cell lung cancer spreads early in the course of the disease and occurs almost exclusively in smokers. Surgical removal usually isn't an option for this type of cancer; instead, it's best treated with chemotherapy and radiation. Even so, the five-year survival rate for small cell lung cancer is very low.

• Non-Small Cell Lung Cancer (NSCLC). Non-small cell lung cancer, which is more common, accounts for more than 75 percent of lung cancers. If caught early when it's confined to a small area, it often can be removed surgically. There are four major categories of non-small cell lung cancer:
• Squamous cell carcinoma: is a cancer that begins in squamous cells, which are thin, flat cells found in the passages of the respiratory and digestive tracts as well as in the surface of the skin and the lining of the hollow organs of the body. This type of NSCLC is linked to a history of smoking and usually found centrally, near a bronchus. It is also called epidermoid carcinoma. This cancer forms in cells lining the airways. It's the most common type in men.
• Adenocarcinoma: This type of cancer usually begins in the mucous-producing cells of the lung. It's the most common type in women and in people who have never smoked or were exposed to secondhand smoke.
• Large cell carcinoma: is a type of lung cancer in which the cells are large and look abnormal when viewed under a microscope. It can be found in any part of the lung and tends to grow and spread rapidly. This type of cancer originates in the peripheral part of the lungs.
• Bronchoaveolar carcinoma: This uncommon type of non-small cell lung cancer tends to grow more slowly than other forms of the disease. It occurs more often in smokers than in nonsmokers and tends to arise in more than one location at the same time.

What causes lung cancer?

Although smoking is by far the leading risk factor for lung cancer, it is known that there are several other risk factors linked to the disease. Some of the risk factors for lung cancer are discussed below:

1. Smoking

Tobacco smoking is believed to be responsible for 80 percent of all cases of lung cancer. The risk of lung cancer increases with the length of time a person has been smoking, the number of packs per day smoked, and how deeply the smoke is inhaled. However, if a person quits smoking before lung cancer develops, the lung tissue slowly returns to normal, which lowers the risk of lung cancer.

Some people think that smoking cigars and pipes is less harmful than smoking cigarettes. However, research has shown that cigar and pipe smoking are almost as likely to cause lung cancer as cigarette smoking. Even cigar and pipe smokers who do not inhale are at increased risk for lung, mouth and other types of cancers.

Secondhand smoke, also called environmental tobacco smoke, describes the smoke in the air when someone else smokes. Exposure to secondhand smoke is called involuntary or passive smoking and increases lung cancer risk. For example, nonsmoking spouses of smokers and people exposed to tobacco smoke in the workplace are more likely to get lung cancer.

2. Asbestos

Asbestos is any of several minerals that occur naturally as fibers. These fibers tend to break easily into particles, which can float in the air and become inhaled, where they can lodge in the lungs, damaging cells and increasing the risk for lung cancer. Formerly used as fireproof insulating materials, asbestos is rarely used today in the workplace or in home products, as it has since been implicated as a cause of certain cancers.

Workers who have been exposed to large amounts of asbestos — such as those in industries like shipbuilding, insulation work, and asbestos mining and manufacturing — have a higher risk of getting lung cancer. The risk of lung cancer is even higher among asbestos workers who also smoke.

3. Radon

Radon is an invisible, odorless and tasteless radioactive gas that occurs naturally in soil and rock. It can cause damage to the lungs that may lead to lung cancer. People who work in mines may be exposed to radon; occasionally, radon can also accumulate indoors. Radon levels in homes may be measured by a kit found in most hardware stores.

4. Marijuana

Many of the carcinogens found in tobacco are also found in marijuana, which actually has more tar than regular cigarettes. Research suggests that marijuana may also cause cancers of the mouth and throat.

5. Lung diseases

Certain lung diseases, such as tuberculosis and some types of pneumonia, often leave scars on the lung that can increase the risk of developing lung cancer.

6. Personal and family history

A person who has had lung cancer once is at increased risk for developing a second lung cancer. Siblings and children of people who have had lung cancer may also have a slightly higher risk.

What are the symptoms of lung cancer?

Because most lung cancers do not cause any symptoms until they have spread, only about 15 percent of lung cancers are found in the early stages. When lung cancer is found early, it is often as a result of a chest X-ray, CT scan or other test that was being done for another reason. Symptoms of lung cancer may include:

• A cough that does not go away and gets worse over time.
• Constant chest pain, often made worse by deep breathing.
• Hoarseness.
• Weight loss and loss of appetite.
• Coughing up blood.
• Shortness of breath.
• Recurring infections such as bronchitis and pneumonia.
• New onset of wheezing.
• Swelling of the neck and face.
  

Remember that these symptoms may be caused by conditions other than lung cancer. It is important to check with a doctor.

Diagnostic Tests for Lung Cancer:



If there is any reason to suspect lung cancer, the doctor will take a medical history and conduct a physical exam. The doctor may also order a chest X-ray and other tests. If lung cancer is suspected, sputum cytology (the microscopic examination of cells obtained from a deep-cough sample of mucus in the lungs) is a simple test that may be useful in detecting lung cancer.

To confirm the presence of lung cancer, the doctor must examine tissue from the lung. A biopsy — the removal of a small sample of tissue for examination under a microscope by a pathologist — can show whether a person has cancer. A number of procedures may be used to obtain this tissue:

* Bronchoscopy: The doctor puts a bronchoscope (a thin, lighted tube) into the mouth or nose and down through the windpipe and into the bronchi. This test can help find tumors or it can be used to take samples of tissue or fluids to see if cancer cells are present.

* Needle aspiration: A needle is inserted through the chest into the tumor to remove a sample of tissue.

* Thoracentesis: Using a needle, the doctor removes a sample of the fluid that surrounds the lungs. This test is done to check whether fluid around the lungs is caused by cancer or by a benign condition such as heart failure or an infection.

* Thoracotomy: Surgery to open the chest is sometimes needed to diagnose lung cancer. This procedure is a major operation performed in a hospital.

If the diagnosis is cancer, the doctor will conduct additional tests to determine the stage (or extent) of the disease (stages of lung cancer are discussed later). Some tests used to determine the cancer stage include:

* Computed tomography (CT) scan: A CT scan is an X-ray procedure in which the X-ray beam moves around the body, taking pictures from different angles. These images are combined by a computer to produce a detailed cross-sectional picture of the inside of the body.

* Magnetic resonance imaging (MRI): MRI uses large magnets and radio waves to produce computer-generated cross-sectional pictures of internal organs.

* Radionuclide scanning: Scanning can show whether cancer has spread to other organs, such as the liver. The patient swallows or receives an injection of a mildly radioactive substance. A machine (scanner) measures and records the level of radioactivity in certain organs to reveal abnormal areas.

* Bone scan: A bone scan is a type of radionuclide scanning that can show whether cancer has spread to the bones.

* Mediastinoscopy: A mediastinoscopy can help show whether the cancer has spread to the lymph nodes in the chest. With the patient asleep, tissue samples are taken from the lymph nodes along the windpipe through a small hole cut into the neck. Examining the tissue under a microscope can show if cancer cells are present.

* Bone marrow biopsy: A needle is used to remove a small piece of bone, usually from the back of the hipbone, and the sample is checked for cancer cells.

* Blood tests: Certain blood tests are often done to help see if the lung cancer has spread to the liver or bones.

Lung Cancer Treatment

Lung cancer treatment depends on the type and stage of cancer, as well as the overall health of the patient.

Treatment may include surgery to remove the cancer, radiation therapy, or medications (chemotherapy). Treatment for non–small and small cell cancer may be different.

Lung cancer treatment may include one or more of the following therapies:

1. Surgery

Surgery is taking out the cancer. Surgery is the most effective treatment for early-stage non–small cell lung cancers (stages I and II). In some cases, only the portion of the lung that contains the tumor is removed. In others, one lobe or even the entire lung may be taken. Surgery to remove all or part of a lung often involves opening one side of the chest, a procedure called a thoracotomy.

Operations to treat lung cancer include:

• Wedge resection: In this operation, the doctor removes only the section of the lung that contains the tumor along with a margin of normal tissue.
• Lobectomy: The most common type of surgery, lobectomy involves removing an entire lobe of one lung.
• Pneumonectomy: In this operation, an entire lung is removed. Because pneumonectomy will decrease lung function considerably, as well as lead to other complications, it's performed only when absolutely necessary and then only if the patient breathing capacity is sufficient to allow breathing with a single lung.
  

Lung function studies and a lung scan are often done before surgery to predict whether the patient will have enough remaining lung function after surgery to live a fairly normal life.

2. Radiation therapy

Radiation therapy uses high-dose X-rays to kill cancer cells. Radiation therapy is often used in combination with surgery or chemotherapy or both. Radiation following surgery for stages IIA, IIB, and IIIA (with lymph node involvement) may reduce the risk of cancer returning in the chest.

The way in which radiation is delivered depends on the type and stage of the cancer being treated. Radiation therapy may be given before, during or after chemotherapy. In all cases, however, the goal of treatment is to destroy cancer cells while harming as little normal tissue as possible.

Small cell lung cancer often spreads to the brain. For that reason, the doctor may sometimes recommend brain radiation therapy to prevent cancer from metastasizing to that part of the body or to eliminate micrometastases that aren't yet detectable with imaging studies. Brain radiation therapy can cause short-term memory problems, fatigue, nausea and other serious side effects.

3. Chemotherapy

Because most small cell lung cancers have spread beyond the lungs by the time they're discovered, an operation usually isn't a treatment option. Instead the most effective treatment is chemotherapy, either alone or in combination with radiation therapy.

Chemotherapy uses medications or drugs to kill cancer cells. Chemotherapy is the most effective treatment for small cell lung cancer, but it is only a cure in a small number of people. Chemotherapy has been shown to improve survival in non-small lung cancer when it is given after surgery for stages IB, IIA, IIB, and IIIA. It may also be used to treat more advanced stages (stages III and IV) of non–small cell lung cancer.

In cases of small cell lung cancer, chemotherapy may be used to shrink the cancer, to slow the cancer's growth, to prevent it from spreading further, or to relieve symptoms and make the patient more comfortable (palliative care). A combination of drugs usually is given in a series of treatments over a period of weeks or months, with breaks in between so that the body can recover. Even so, because the drugs damage healthy cells along with malignant ones, they can cause serious side effects.

4. Targeted therapy

Targeted therapies use medications or antibodies to block growth factors that allow some cancers to grow. At this time, targeted therapies are used for advanced stages.

resource: Cancer Info Guide

Staging of Lung Cancer:

TNM staging is a process to measure how advanced the cancer is. The following three factors are considered:

* Tumor - size and location
* Node - lymph node involvement
* Metastasis - has the cancer spread

1. Small cell lung cancer staging:

Limited stage : The cancer is only in one lung and in lymph nodes on the same side of the chest.

Extensive stage : The cancer has spread to the other lung, to lymph nodes on the other side of the chest, or to distant organs. Many doctors consider cancer that has spread to the fluid around the lung to be extensive stage as well.

2. Non-small cell lung cancer staging:

Stage 0 : The cancer is limited to the lung and is found in a few layers of cells only. It has not grown through the top lining of the lung. Stage 0 is also called carcinoma in situ.

Stage : The cancer is in the lung only, with normal tissue around the tumor. Stage I is divided into stages IA and IB, based on the size of the tumor.

Stage II : The cancer has spread to nearby lymph nodes or to the chest wall (the ribs and muscles that make up the area of the body between the neck and abdomen); the diaphragm (thin muscle below the lungs and heart that separates the chest from the abdomen); the mediastinal pleura (thin membrane that covers the outside of the lungs in the area near the heart); or the parietal pericardium (outer layer of tissue that surrounds the heart). Stage II is divided into stage IIA and stage IIB, based on the size of the tumor and whether it has spread to the lymph nodes.

Stage III : The cancer has either:
* Spread to the lymph nodes in the mediastinum (middle area between the lungs that contains the heart, major blood vessels and other structures);or
* Spread to the lymph nodes on the opposite side of the chest or in the lower neck.

Stage III is divided into stage IIIA (which is sometimes treated with surgery) and stage IIIB (which is rarely treated with surgery).

Stage IV : The cancer has spread to other parts of the body or to another lobe of the lungs.

Resource:
National Cancer Institute
MEDLINEplus Health Information
CancerGuide