What is lung cancer?
Lung cancer is the uncontrolled growth of abnormal cells in the lung. The uncontrolled reproduction of cells results in the formation of tumors that can block or compress airways and displace or damage normal lung tissue. This can make the lung stop functioning as it should.

Lung cancer takes many years to develop. As individuals are exposed to agents known to cause lung cancer, small changes begin to occur.  Abnormal cells may appear in the tissues lining the airways. If exposure to the substances continues, these cells will increase and gradually become cancerous and form a tumor, causing lung cancer.
 
Most lung cancers start in the lining of the bronchi (air passageways branching off the trachea, or breathing tube). That is why another term for lung cancer is bronchogenic cancer, meaning originatiing in the bronchi.  Lung cancer can also form in glands below the lining of the bronchi, frequently in the periphery of the lungs.

There are two major types of lung cancer, identified by how the cells look under a microscope. Each type of lung cancer grows and spreads in different ways and is treated differently. About 90 percent of lung cancers are of one of these two types:

Non-small cell lung cancer
Non-small cell lung cancer is much more common, and usually grows and spreads more slowly than small cell lung cancer. There are three main types of non-small cell lung cancer, named for the type of cells in which the lung cancer develops:

1. Squamous cell carcinoma (also called epidermoid carcinoma) usually starts in one of the larger breathing tubes and grows relatively slowly. The size of these lung tumors can range from very small to quite large.
   
2. Adenocarcinoma starts growing near the outside surface of the lung and may vary in both size and growth rate. Some slowly growing adenocarcinomas are called broncheoalveolar cancer.
   
3. Large cell carcinoma starts near the surface of the lung, grows rapidly, and is usually large when diagnosed.

Small cell lung cancer
Small cell lung cancer, sometimes called oat cell cancer, is less common than non-small cell lung cancer. This type of lung cancer usually starts in one of the larger breathing tubes, grows fairly rapidly, and is likely to be large by the time of diagnosis. Small cell lung cancer accounts for about 20 percent of all lung cancers.

There are more than a dozen other kinds of lung cancer. Some of the less common types include carcinoid, and malignant mesothelioma. These cancers constitute about 5 to 10 percent of lung cancers.

How common is lung cancer?
Lung cancer is one of the most common cancers in the United States, accounting for about 15 percent of all cancer cases, or 173,000 new cases each year. Lung cancer is the leading cancer killer in both men and women, accounting for approximately 160,000 deaths in the United States in 2004.

In the United States, over half of the lung cancer cases occur in men, but the number of cases on lung cancer found in women is increasing and will soon equal that in men.

Today more women die of lung cancer than of breast cancer.  While the rate of lung cancer cases appears to be dropping among white and African-American men, it continues to rise among both white and African-American women.

What causes lung cancer?
Smoking. Although lung cancer can develop in patients who never smoked, 87 percent of lung cancer cases are caused by smoking. This makes smoking the leading cause of lung cancer. Cigarette smoke contains more than 4,000 different chemicals, many of which are proven to be carcinogens. These substances damage the cells in the lungs and over time the damaged cells may become cancerous, leading to lung cancer.

The likelihood that a smoker will develop lung cancer is affected by how early they start smoking, how long they have smoked, and how many cigarettes they smoke per day. It is also affected by how deeply they inhale the smoke.

Important information about lung cancer:

• Stopping smoking at any time reduces a person's risk for developing lung cancer.
• Cigar and pipe smokers also have a higher risk of lung cancer than non-smokers.
• Second-hand smoking or environmental exposure to tobacco smoke (also known as passive smoking) increases the person’s risk for developing lung cancer.

Radon
Radon occurs naturally in soil and rock and can cause lung damage that can in turn lead to cancer of the lungs. Radon exposure can occur in people who work in mines. This radioactive, odorless and tasteless gas can also be found in some homes, schools and workplaces. The EPA estimates that nearly one out of every 15 homes in the U.S. has indoor radon levels at or above the level at which homeowners should take action -- 4 picocuries per liter of air (pCi/L) on a yearly average.

There are tests that help detect radon in homes and buildings and the problem can be fixed. It is important to know that smoking increases the risk of lung cancer even more in individuals who had radon exposure.

Asbestos
Asbestos fibers are a group of minerals used in industries such as ship building, insulation work and brake repair. Workers who have been exposed to large amounts of asbestos have a three- to four-fold higher risk of developing lung cancer than those who have not been exposed to asbestos. The risk of lung cancer is even higher among asbestos workers who also smoke. Asbestos workers should use protective equipment and follow recommended safety measures.

Pollution
There is research that suggests a link between lung cancer and exposure to certain air pollutants, such as byproducts of the combustion of diesel and other fossil fuels.
Lung diseases.   Certain lung diseases, such as tuberculosis (TB), increase a person's chance of developing lung cancer. Lung cancer tends to develop in areas of the lung that are scarred from TB.

A person who has had lung cancer once is more likely to develop a second lung cancer compared with a person who has never had lung cancer.

What are the symptoms of lung cancer?
Lung cancer and its symptoms can go undetected for several years. Because of the large size of the lungs and the way the nerves in the lung function, cancer cells can grow into large tumors and even spread outside the lung without causing suspicion or displaying prominent symptoms of lung cancer.

Another reason for the typical delay in detection of lung cancer is that the most common symptom of lung cancer is a “persistent or chronic cough,” which individuals can mistake for a cold or bronchitis.

Other symptoms of lung cancer may include hoarseness of voice, shortness of breath, wheezing, coughing up blood, weight loss, lack of appetite, fever without obvious cause, repeated bouts of bronchitis or pneumonia and chest pain.

These symptoms of lung cancer can occur with a variety of other lung diseases and conditions. Individuals with these symptoms should see their doctor to find out the cause of their symptoms.

Another lung cancer symptom of lung cancer is chest, shoulder, or back pain, which feels like a constant ache that may or may not be related to coughing. There may also be some swelling of the neck and face.

Some lung cancer symptoms may occur that do not seem to be related to the lungs. These may be caused by the spread of lung cancer to other parts of the body. Depending on which organs are affected, symptoms can include headaches, weakness, pain, bone fractures, bleeding or blood clots.

Common symptoms of lung cancer:

• Persistent or chronic cough
• Hoarseness of voice
• Shortness of breath
• Wheezing
• Coughing up blood
• Weight loss
• Lack of appetite
• Fever without obvious cause
• Repeated bouts of bronchitis or pneumonia
• Chest pain

How is lung cancer diagnosed?
To help find the cause of symptoms, your doctor will evaluate your medical history, smoking history, exposure to environmental and occupational substances, and family history of cancer. Your doctor will also perform a physical exam and will order a variety of tests including a chest X-ray.

Medical history and physical exam - When a person goes for a lung exam, the doctor will ask many questions about the person's medical history, including questions about exposure to substances known to increase the risk of development of lung cancer. The doctor will also ask questions about the patient’s symptoms and give the patient a physical exam.

Sputum cytology - If the patient has a cough that produces sputum or mucus, it may be examined for cancer cells. This test is called “sputum cytology” and it involves obtaining a deep-cough sample of the mucus in the lungs and sending it out for microscopic examination. This is a simple test that may be useful in detecting lung cancer. In some cases, sputum cytology can reveal lung cancers in patients with normal X-rays or can determine the type of lung cancer. Because it cannot pinpoint the tumor's location, a positive sputum cytology test is usually followed by further tests.

Imaging tests - If lung cancer is suspected, the doctor may order a chest X-ray as a first step in diagnosis. Frequently, a CT (computer assisted tomography) scan or an MRI (magnetic resonance imaging) will also be performed. CT scans and MRIs can show the size, shape and location of a tumor. They are very useful tools in finding out if the tumor has spread from the lung to other parts of the chest or to other parts of the body.

A growing number of doctors are using a form of CT scan in smokers to spot small lung cancers, which are more likely than large tumors to be cured. The technique, called helical low-dose CT scan, is much more sensitive than a regular X-ray and can detect tumors when they are small.  More studies on this type of screening will show whether routine screening of smokers and others at risk for lung cancer will save lives.

Bronchoscopy - The doctor may insert a small tube called a bronchoscope (a thin, lighted tube) through the nose or mouth and down the windpipe, to look inside the airways and lungs and take a sample, or biopsy, of the tumor. This is just one of several ways in which a doctor may take a biopsy sample.

Biopsy - To confirm the presence of lung cancer, the doctor must examine tissue from the lung. A biopsy is a test in which tissue is removed from the suspected tumor area and looked at under a microscope to see if cancer cells are present.  A biopsy is necessary for the doctor to confirm a cancer diagnosis and to identify the specific type of cancer you have. A number of procedures may be used to obtain this tissue:

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 to check for cancer cells.

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

Staging lung cancer

What is "Staging"?
When lung cancer is diagnosed, the doctors want to learn the stage of the disease. Staging is a process used by physicians to describe the extent of the disease or how advanced the cancer is. Staging assists the physician in determining the likely course of the cancer and how it may respond to different treatments (also known as the prognosis of the disease).

Lung cancer for example, often spreads to the brain or bones. Knowing the stage of the disease helps the doctor plan an appropriate treatment approach and evaluate the results of different interventions. Different staging systems are used for different types of cancer.

As mentioned above, CT and MRI are often used to determine whether the cancer has spread.  In addition, radionuclide 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. 

A bone scan, one type of radionuclide scanning, can show whether cancer has spread to the bones. A small amount of radioactive substance is injected into a vein. It travels through the bloodstream and collects in areas of abnormal bone growth. An instrument called a scanner measures the radioactivity levels in these areas and records them on X-ray film.

A mediastinoscopy can help show whether the cancer has spread to the lymph nodes in the chest. Using a lighted viewing instrument, called a scope, the doctor examines the center of the chest (mediastinum) and nearby lymph nodes. In mediastinoscopy, the scope is inserted through a small incision in the neck; in mediastinotomy, the incision is made in the chest. In either procedure, the scope is also used to remove a tissue sample. The patient receives a general anesthetic.

Lung Cancer Treatments and Options
Many factors affect the choice of treatments a doctor may recommend for lung cancer. These include the type of lung cancer, the size, location and extent of the disease, whether or not the tumor has spread outside the lungs, the patient’s age and general health including any other serious diseases.

It is important to discuss the goals of lung cancer treatment with your doctor. Some treatments may be used to control the cancer, others may be used to improve the quality of life and/or reduce symptoms. These treatments may be used alone or in combination. 

Lung cancer treatments often have unpleasant side effects or side effects with serious consequences. Side effects depend on the type of treatment and may be different for each person. Side effects are often only temporary. Doctors and nurses can suggest ways to make side effects more manageable and to help relieve symptoms that may occur during and after treatment.

Surgery
Surgery may help cure lung cancer by removing the tumor from the lung. It is used in limited stages of the disease. The type of surgery depends on where the tumor is located in the lung. Some tumors cannot be removed by our cancer surgeons because their size may be too large or because they are too close to vital organs or tissues. 

An operation to remove only a small part of the lung is called a segmental or wedge resection. When the cancer surgeon removes an entire lobe of the lung, the procedure is called a lobectomy. Pneumonectomy is the removal of an entire lung. Some tumors are inoperable (cannot be removed by surgery) because of the size or location, and some patients cannot have surgery for other medical reasons. Surgery for lung cancer is a major operation, which can be performed via minimally invasive techniques.

After lung surgery, air and fluid tend to collect in the chest. Patients often need help turning over, coughing and breathing deeply. These activities are important for recovery because they help expand the remaining lung tissue and get rid of excess air and fluid. Pain or weakness in the chest and the arm and shortness of breath are common side effects of lung cancer surgery. Patients may need several weeks or months to regain their energy and strength.

Radiation Therapy
Radiation therapy is a form of high energy X-ray that kills cancer cells. It is used:

• in combination with chemotherapy and sometimes with surgery
• to offer relief from pain or blockage of the airways

Radiation therapy is directed to a limited area and affects the cancer cells only in that area. Radiation therapy may be used before surgery to shrink a tumor, or after surgery to destroy any cancer cells that remain in the treated area.

Doctors also use radiation therapy, often combined with chemotherapy, as primary treatment instead of surgery. Radiation therapy may also be used to relieve symptoms such as shortness of breath. Radiation for the treatment of lung cancer most often comes from a machine (external radiation). The radiation can also come from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation or brachytherapy).
 
Radiation therapy affects normal as well as cancerous cells. Side effects of radiation therapy depend mainly on the part of the body that is treated and the treatment dose. Common side effects of radiation therapy are a dry, sore throat; difficulty swallowing; fatigue; skin changes at the site of treatment; and loss of appetite. Patients receiving radiation to the brain may have headaches, skin changes, fatigue, nausea and vomiting, hair loss, or problems with memory and thought processes.

Radiosurgery is a form of delivering higher dose of radiation to a small tumor. It could be used sometimes to replace surgery especially in those patients who may not be suitable for surgery.

Chemotherapy
Chemotherapy is the use of drugs that are effective against cancer cells. Chemotherapy may be injected directly into a vein (by IV, or intravenously) or given through a catheter, which is a thin tube placed into a large vein and kept there until it is no longer needed. Some chemotherapy drugs are taken by pill. Chemotherapy may be used:
in conjunction with surgery

• in more advanced stages of the disease to relieve symptoms
• in all stages of small cell cancer

Some patients may also be eligible to participate in clinical trials or research studies that look at new ways to treat lung cancer.

Even after cancer has been removed from the lung, cancer cells may still be present in nearby tissue or elsewhere in the body. Chemotherapy may be used to control cancer growth or to relieve symptoms.

Chemotherapy affects normal as well as cancerous cells.  Side effects depend largely on the specific drugs and the dose (amount of drug given). Common side effects of chemotherapy include nausea and vomiting, hair loss, mouth sores and fatigue.

Photodynamic Therapy (PDT)
This is a type of laser therapy, involves the use of a special chemical that is injected into the bloodstream and absorbed by cells all over the body. The chemical rapidly leaves normal cells but remains in cancer cells for a longer time.

A laser light aimed at the cancer activates the chemical, which then kills the cancer cells that have absorbed it. Photodynamic therapy may be used to reduce symptoms of lung cancer, for example, to control bleeding or to relieve breathing problems due to blocked airways when the cancer cannot be removed through surgery. Photodynamic therapy may also be used to treat very small tumors in patients for whom the usual treatments for lung cancer are not appropriate. 

Photodynamic therapy makes the skin and eyes sensitive to light for six weeks or more after treatment, so patients are advised to avoid direct sunlight and bright indoor light for at least six weeks. If patients must go outdoors, they need to wear protective clothing, including sunglasses. Other temporary side effects of PDT may include coughing, trouble swallowing, and painful breathing or shortness of breath. Patients should talk with their doctor about what to do if the skin becomes blistered, red or swollen.

Treating Small Cell Lung Cancer
Small cell lung cancer spreads quickly. In many cases, cancer cells have already spread to other parts of the body when the disease is diagnosed. In order to reach cancer cells throughout the body, doctors almost always use chemotherapy. Treatment may also include radiation therapy aimed at the tumor in the lung or tumors in other parts of the body (such as in the brain). Some patients have radiation therapy to the brain even though no cancer is found there.

This lung cancer treatment, called prophylactic cranial irradiation (PCI), is given to prevent tumors from forming in the brain. Surgery is part of the treatment plan for a small number of patients with small cell lung cancer.