Lung Cancer

What Is Lung Cancer?

Lung cancer is an uncontrolled growth of abnormal cells in one or both of the lungs.

The body is made up of different types of cells that normally divide and multiply in an orderly way. These new cells replace older cells. This process of cell birth and renewal occurs constantly in the body. Abnormal cells also periodically normally appear but are removed by natural defense mechanisms.

Cancer, also known as a malignant growth, occurs when:

• The body’s natural defenses, such as certain parts of the immune and other protective systems, cannot stop the uncontrolled cell division, cancer begins.
• These abnormal cells become greater and greater in number, and come together to form a tumor, which is a cellular growth that forms a progressively enlarging mass. Such tumors are benign unless they invade surrounding tissues and organs, in which case they are malignant.

Cancerous tumors grow out of control and can invade, replace, and destroy normal cells near the tumor. In some cases, cancer cells spread (or metastasize) to other areas of the body.

Lung cancer generally takes many years to develop even though damage to the lungs may occur shortly after a person is exposed to cancer-causing substances.

Different Types Of Lung Cancer

There are different types of cells in the lung, of varying size, for the different functions of the lung. This has resulted in the classification of two main types of lung cancer:

• Cancer developing from the cells of neural origin in the lung is known as small-cell lung cancer.
• Other types of cancers in the lung are known as non-small-cell lung cancer.
• Some lung cancers are a mixture of both types.

The different types of lung cancers tend to grow and spread differently and are therefore not treated in the same way.

• Non-small-cell lung cancer is the more common type, accounting for about 80% of lung cancers. It is this more common type of lung cancer that grows and spreads more slowly.
• This less common type of cancer, small-cell cancer, is the type that grows more quickly and has a greater chance of spreading to other parts of the body.

Since the more common non-small cell group of cells in the lung are themselves made up of differing kinds of cells, three distinct types of non-small cell lung cancer are recognized. They are:

• Squamous cell carcinoma, often found in the central part of the lung.
• Adenocarcinoma, often occurring in the outer part of the lung.
• Large cell carcinoma, which can occur anywhere in the lung.

People with adenocarcinoma have a more favorable outlook. However, any non-small cell cancers can begin to grow very rapidly and have an unfavorable prognosis.

In general, the choice of treatment and the chances of recovery from lung cancer following treatment will depend on the biological nature of the tumor, which, in turn, is probably related to:

• How advanced the cancer is at the time of diagnosis
• How healthy the person generally is

What Causes Lung Cancer?

The most common cause of lung cancer is smoking.

Smoking causes lung cancer because there are substances within tobacco that are known to cause cancer. These substances are known as carcinogens (which means “cancer-causing agents”), and it is these carcinogens that cause the actual damage to the cells in the lungs. A cell that is damaged may become cancerous over a period of time.

One cannot predict which smoker is at greater risk of developing lung cancer. In general, though, a smoker’s chances of developing cancer depends on:

• The age that the person began smoking
• How long the person has smoked
• How many cigarettes per day the person smokes

Passive smoking – breathing in someone else’s smoke – may also increase the risk for developing lung cancer.

There are other causes of lung cancer not related to smoking. People who smoke and who also are exposed to these other causes have an even higher risk for lung cancer.

These other causes include:

• Exposure to cancer-causing agents through a person’s job. This includes exposure to asbestos, either in the mining or construction industries. Inhaled asbestos particles may remain in the lungs, damaging lung cells. It also includes exposure to certain industrial substances like coal products, vinyl chloride, nickel chromate, arsenic, and exposure to some organic chemicals like chloromethyl ethers.
• Exposure to radiation, either through one’s occupation or for medical reasons, such as repeated x-rays, though this is quite uncommon.
• Radon gas, which occurs naturally in rocks and soil in certain areas, may cause lung damage and may eventually result in lung cancer if it seeps into your home. The presence of radon in the home can be measured using an inexpensive kit that can be purchased at department or hardware stores.

Research suggests that some people are more at risk for developing cancer if their body is not as easily able to deal with certain cancer-causing chemicals. This inability to neutralize cancer-causing chemicals is believed to be inherited.

Researchers also believe that in some people, when they come into contact with certain cancer-causing agents, their immune system, instead of neutralizing them, will actually make these agents more aggressive within the body. Such people, therefore, would be more sensitive to tobacco smoke and chemicals known to cause cancer.

How Is Lung Cancer Diagnosed?

If a doctor suspects lung cancer, he or she will:

• Ask about your medical history
• Perform a physical examination
• Order specialized medical tests

As part of taking your medical history, your doctor will ask about:

• Whether you smoke or have smoked in the past
• Your occupation
• Whether you have been exposed to certain occupational hazardous substances or radiation
• Whether you have a family history of lung cancer

Medical tests that may be performed include:

• Chest x-ray. This is the first and basic test that will be ordered.
• CT or MRI scans. These are highly specialized tests with computer-generated images showing slices and other views of the lung.
• Sputum test. This is the examination under a microscopy of a sample of the mucus you cough up. If an abnormality seen on an x-ray is suggestive of cancer, a sputum test may be ordered. Though this test is not usually as sensitive as a biopsy, in many cases microscopic examination of the expectorated cells will reveal cancer.
• Biopsy. This is the removal of a sample of tissue from the body to be examined under a microscopy. A biopsy is the usual way that the doctor can be absolutely certain that lung cancer is present. A physician who specializes in tissue analysis (a pathologist) can then see what type of cell is causing the growth and whether or not it is a cancerous cell.

There are different ways in which a biopsy of the lung may be obtained.

• Needle aspiration. While you are sedated, a doctor will insert a needle through your chest directly into the growth and, guided by x-rays, will remove a sample of tissue. Alternatively, the needle may be pushed only as far as the envelope of tissue that surrounds the lungs, removing fluid from this layer to check for the presence of cancer cells. This technique is preferable for tumors which are in the outer part of the lung.
• Bronchoscopy. In this procedure, which is more common than needle aspiration, a doctor passes a narrow, flexible, well-lit tube, called a bronchoscope, into your lungs while you are under sedation. The bronchoscope is passed through either your mouth or nose directly into your windpipe, and the doctor is able to see the air passages inside the lungs. The biopsy of any suspicious part of the lung can be performed through this tube. This technique is preferable for tumors that are in the central part of the lung.

For more detailed information about this procedure, go to Bronchoscopy.

Rarely, even after all the above medical tests, the diagnosis may still be unclear. In this case, a major operation exposing the lung may be needed. This procedure is known as a thoracotomy.

How Is Lung Cancer Treated?

The treatment of lung cancer depends on its type and extent. Therefore, the doctor must obtain specific information before suggesting a treatment. The doctor will need to know:

• The type of lung cancer the patient has – whether small-cell lung cancer or non-small-cell lung cancer
• The size of the growth
• Exactly where in the lung it is
• Whether the cancer has spread, and, if so, how far

Obtaining all this information is known as staging the cancer. “Staging” is a method that has been developed to describe the extent of cancer growth. Staging helps to predict:

• How an individual is expected to fare over time
• The chances that the cancer will come back (recur)

Staging allows the physician to customize cancer treatment. In general, the lower the stage the better the person’s prognosis (expected outcome).

Lung cancer is “staged” by information that is obtained from the biopsy and the results of the various imaging studies, such as chest x-ray or CT scan. The physician uses all available findings to determine the stage that best describes the person’s condition.

Tests performed for staging may include:

• CT scan or MRI scan or both. Computerized images are obtained from both of these tests, which allows the lung to be seen in thin slices, clearly showing the extent of any growth within the lung. These tests may also be performed on other parts of the body if there is suspicion that the growth may have spread to other parts of the body.

  For more detailed information about MRI scans, go to MRI scan.

  For more information about CT scans, go to CT scan.

• Other scanning techniques include various forms of radionuclide scanning and bone scans. These tests can help detect whether the cancer has spread to other organs in the body or to the bones. A low dose of harmless radioactive substance is injected into a vein, and as it travels around the body a specialized scanning machine is able to record radioactivity levels throughout the body. Since the uptake of the radioactive material is different in areas of the body affected by cancer, these areas are readily identified.

• A further specialized test called mediastinoscopy may be offered. This procedure is done while a patient is under general anesthesia. A narrow telescope, to which a camera may be attached, is introduced into the front of the chest through a small incision, or sometimes through a small incision in the neck. A sample of tissue can then be removed from the lymph nodes and other nearby tissue.

Understanding Lung Cancer “Staging”

“Staging” is a method that has been developed to describe the extent of the cancer growth, based on the results of biopsy and other investigations. This information helps to predict how an individual will fare over time. Staging a cancer also allows a physician to customize the cancer treatment to a particular individual.

In lung cancer patients, staging methods are used for non-small-cell lung cancers, which account for about 80% of all cancers.

The TNM cancer staging system is defined as:

• T (for tumor)
• N (for lymph nodes)
• M (for metastasis, or spread of the cancer)

T refers to the size of the tumor itself:

• TX and T0 – Cancer cells have been found in sputum or lung tissue but cannot be seen.
• Tis – Carcinoma in situ, which means cells are cancerous but the growth does not show evidence of spreading.
• T1 – The tumor is small, still contained in the lung, and has not reached the main airway.
• T2 – The tumor has one or more of the following characteristics: it is larger than 3 cm; it involves the main airway; it is close to the windpipe; it has invaded the membrane covering the lung; it has damaged or inflamed the lung tissue but has not affected the entire lung.
• T3 – The tumor has invaded the chest wall, diaphragm, membrane covering organs in the chest, or the outer wall of the membrane around the heart, and/or it has affected the entire lung.
• T4 – The tumor has invaded the area between the lungs, heart, major blood vessels of the heart, trachea, esophagus, or spine, and/or separate tumors are present in the same lung lobe, and/or cancer is present in fluid between the membrane covering the lung and the lung (pleural effusion).

N refers to whether the cancer has reached the lymph nodes:

• N0 – Lymph nodes are cancer-free.
• N1 – Cancer has spread to nearest lymph nodes around the airways.
• N2 – Cancer has spread to lymph nodes in the middle of the chest that are adjacent to the affected lung.
• N3 – Cancer has spread to lymph nodes in the middle of the chest that are adjacent to the opposite lung, to lymph nodes in nearby or opposite muscle tissue, or to lymph nodes above the collar bone.

M refers to metastasis, or spread of the cancer:

• M0 – Metastasis has not occurred.
• M1 – Cancer has spread to distant locations within the body.

This information is compiled to determine a staging category for the cancer. In general, the lower the staging category, the better the expected outcome.

• Stage I – The cancer growth is confined to the lung and is surrounded by normal lung tissue.
• Stage II – The cancer has spread to the nearby lymph nodes (these are structures that drain lymph fluid from the lungs).
• Stage III – The cancer has now spread outside of the lung, to the chest wall or to the diaphragm muscle beneath the lungs, or to the lymph nodes on the other side of the chest, or to the lymph nodes in the neck. Stage III is divided into Stage IIIa, implying that the cancer may still be removed by surgery, and Stage IIIb, in which the cancer cannot be removed by surgery.
• Stage IV – The cancer has broken away from the original cancer growth and has spread beyond the lungs to other parts of the body. This is known as metastasis of the cancer.

Treatment Options

The treatment of lung cancer will usually consist of a combination of therapies, rather than a single therapy, which may result in a better outcome. The different treatment modalities include:

• Chemotherapy. This involves the use of medications that are able to kill cancer cells. Chemotherapy may be selected as the major treatment to kill the cancer cells, or as a treatment to kill any remaining cancer cells either alone or in conbination with surgical removal of the tumor. It also can be used to treat a cancer growth elsewhere in the body.

  Chemotherapy drugs are mainly given through a catheter, which is a thin tube that is placed into a large vein. The catheter may be left in place for the duration of the treatment or removed after each treatment session. A number of chemotherapy drugs are available as a pill.

• Radiation therapy. Radiation therapy involves the use of high-dose x-rays to destroy the cancer cells or make the growths smaller. It is also used after surgery to destroy any remaining cancer cells. Radiation therapy can be directed precisely to those areas in the body to where cancer has spread, such as the bones, brain, or spine.

  For more detailed information about radiation therapy, go to Radiation Therapy.

• Surgery. Depending on the “stage” of the cancer, a number of surgical options are available. A wedge resection involves removing a small part of the lung in which the growth is located. Alternatively, a whole lobe of the lung may be removed, in a procedure is known as a lobectomy. On occasions, it may be necessary to remove the entire lung; this procedure is called a pneumonectomy. A new type of less invasive surgery – video assisted thoracoscopic surgery or VATS – has been introduced to remove tumors which are near the outer edges of the lung. Usually 3 small incisions instead of one large incision are made with this type of surgery and recovery is faster.
• Photodynamic therapy. Photodynamic therapy is a newer treatment, used more often during clinical trials. Photodynamic therapy is used only for tumors in the main central airways that either recur after surgery or chemotherapy or, because of their location and/or size, are not amenable to surgery. It involves the use of a laser light aimed at the cancerous growth, which activates a chemical that has been injected into the blood stream and is absorbed and held for a period of time by cancer cells (while normal cells release the chemical quickly). The chemical, activated by the laser, then kills the cancer cells.
• Other experimental therapies. This includes immunotherapy, which uses drugs to boost a person’s immune system to fight cancer. It also includes gene therapy, which involves methods to attack genetic mutations that are causing the cancer. Under investigation are angiogenesis inhibitors, which are agents that inhibit the formation of new blood vessels that are critical to the spread of cancer.

What Can I Expect?

Each particular treatment for lung cancer may have some adverse effects. Some of those effects may last a very short period, while others may last for a few months and yet others may be permanent. If you have lung cancer, be sure to discuss side effects of each treatment with your doctor. Often, medication or other steps can be taken to help relieve some of those effects.

Side Effects

Both radiation therapy and chemotherapy may cause fatigue, adding to the already weakened body from the cancer. Therefore it is important to rest, exercise, and maintain a healthy diet.

Talk to your doctor and the cancer care team about the best ways to stay healthy and remain as fit as possible.

Emotional Support

Any cancer diagnosis is difficult. There are many support groups to help individuals and their loved ones deal with cancer, its treatment, and its effect on the body. Your doctor and cancer care team can help you find the emotional support you may need.

Following Up

Your doctor will arrange for regular follow-up care to determine how well you are responding to the various treatments. Further tests, including chest x-rays and blood tests, may be needed to determine how you are responding to treatment.

It’s important to report any new or recurring symptoms to your doctor.

You also may also wish to obtain information about clinical trials in which you may participate. A clinical trial is a research study to determine the effectiveness of newer treatments. The aim of a clinical trial is to improve the current available treatments offered based on the results of newer scientific information.

Information about clinical trials may be obtained from your doctor or may be obtained directly from the National Cancer Institute’s Cancer Information Service at 1-800-4-CANCER (800-422-6237) or at http://cancertrials.nci.nih.gov.

Pulmonary Rehabilitation

Many hospitals now offer pulmonary rehabilitation programs, which are designed to help people with all types of lung disease, including lung cancer, live as independently and fully as possible. The programs combine exercise and education in order to help individuals cope with lung disease and improve the quality of their lives.

Participants in the program are carefully monitored as they exercise on treadmills or use other equipment, such as rowing machines, while learning to control their breathing in order to fill their lungs efficiently and effectively.

Participation in a pulmonary rehabilitation program can:

• Help people to better perform activities of daily living, such as walking up stairs, performing light housework, and caring for themselves
• Decrease experiences with shortness of breath
• Possibly reduce the need for hospitalizations or visits to the doctor

Pulmonary rehabilitation is approved by Medicare, and most insurance companies cover the cost.

The Outlook

The long-term outcome once a lung cancer is diagnosed will depend on a number of factors.

• Whether the lung cancer is of the non-small-cell type or small-cell type. The former tends to grow more slowly and is usually detected in the earlier stages, when treatment is likely to be more effective.
• The stage of the cancer at the time of diagnosis. Lung cancer treated at an earlier stage will have a better outcome.
• How healthy the person is. People who are not well enough to walk around freely do not generally do as well as others. It has also been recognized that increasing weight loss before the diagnosis worsens the outlook.
• The five-year survival rate is approximately 50% in those cases when the cancer is still in the early stage when first diagnosed. It drops to about 15% when considering all stages.

Lung Cancer: Frequently Asked Questions

Here are some frequently asked questions related to lung cancer:

Q: Is it possible to determine if early lung cancer is present, in long-standing smokers or previous smokers, when there are no symptoms and the person appears perfectly healthy?

A: A new type of X-ray called spiral low-dose CT scanning, from which computer images showing slices of the entire lung are made available, has shown success in detecting the presence of early lung cancer. However, before deciding to be examined by this technique, you should understand that a number of noncancerous and harmless changes that are not easily distinguished from lung cancer may be seen. To exclude lung cancer, a number of expensive and potentially invasive tests may then be necessary. Also, whether in the long run this will make a difference to the survival pattern of those diagnosed with lung cancer is not yet known. Other tests are also being developed, particularly studying damage to DNA within cells taken from the lung.

Q: Should I participate in a clinical trial?

A: A clinical trial is a research study to determine the effectiveness of newer treatments. The aim of a clinical trial is to improve the current available treatments offered based on the results of newer scientific information. Clinical trials are conducted only on drugs and methods that have already been effective in managing cancer. New treatments are first tested in laboratories and in animal studies, and if they show promise, they are then evaluated further with human studies. Participation in clinical trialsInformation about clinical trials may be obtained from your doctor or may be obtained directly from the National Cancer Institute’s Cancer Information Service at 1-800-4-CANCER (800-422-6237) or at http://cancertrials.nci.nih.gov.

Q: Why is it that some smokers will develop lung cancer while others won’t?

A: Research suggests that some people are more at risk for developing cancer if their body is not as easily able to deal with certain cancer-causing chemicals. This inability to neutralize cancer-causing chemicals is believed to be inherited. Researchers also believe that in some people, when they come into contact with certain cancer-causing agents, their immune system, instead of neutralizing them, will actually make these agents more aggressive within the body. Such people, therefore, would be more sensitive to tobacco smoke and chemicals known to cause cancer.

Q: I’m a former smoker, and I’ve been coughing a lot. Could I have lung cancer?

A: The symptoms that may suggest lung cancer are similar to symptoms of other lung conditions that may not be as serious as lung cancer. The main symptoms of lung cancer are coughing up blood, and coughing that does not seem to improve and gets worse with time. Other symptoms are chest pain, shortness of breath, frequent bouts of pneumonia, weight loss, and feeling tired. The only way to tell if your coughing is related to lung cancer is to see your doctor. Lung cancer can take years to make itself manifest. It is not unusual for lung cancer to appear 4 or 5 years after smoking cessation. Though smoking conveys a lifetime risk of lung cancer, that risk drops dramatically after 10 years.

Lung Cancer: Putting It All Together

Here is a summary of the important facts and information related to lung cancer:

• Smoking by far is the major cause of lung cancer. Other causes include breathing someone else’s smoke, being exposed to cancer-causing chemicals, and being exposed to radiation.
• Lung cancer generally takes many years to develop even though damage to the lungs may occur shortly after a person is exposed to cancer-causing substances.
• The two main types of lung cancer are small-cell lung cancer, which is less common, and non-small-cell lung cancer, which accounts for about 80% of cases.
• The main symptoms of lung cancer are coughing up blood and coughing that does not seem to improve and gets worse with time. Other symptoms are chest pain, shortness of breath, recurrent episodes of pneumonia, weight loss, and feeling tired.
• Lung cancer is diagnosed with x-rays, an analysis of sputum (material a person coughs up), and biopsy of tissue from the lung.
• Lung cancer is “staged” based on the extent of the cancer growth and whether it has spread. Staging helps determine the best treatment for the type of cancer. Generally, the lower the stage, the better the person’s prognosis (expected outcome).
• Treatment for lung cancer includes chemotherapy, radiation therapy, and surgery. Other treatments that may be considered are photodynamic therapy and experimental treatments such as immunotherapy and gene therapy.
• The long-term outcome for people with lung cancer depends on the stage at which the cancer was detected and the general health of the person. When lung cancer is detected in its early stages, the five-year survival rate is about 50%.

Lung Cancer: Glossary

Here are definitions of medical terms related to lung cancer:

Biopsy: The removal of a small amount of tissue from the body for study under a microscope.

Carcinogen: A substance that causes the development of cancer.

Diaphragm: The muscular tissue that separates the chest and the abdominal cavities, which aids breathing by moving up and down.

Malignant: Cancerous; a growth that tends to spread to surrounding tissues or organs

Metastasis: Spread of cancer from one part of the body to another.

Non-small-cell lung cancer: This is the more common type, accounting for about 80% of lung cancers. This type grows and spreads more slowly than small-cell lung cancer.

Small-cell lung cancer: Cancer developing from the smaller cells in the lung; this is a less common type of lung cancer. This type grows more quickly and has a greater chance of spreading to other parts of the body than non-small-cell lung cancer.

Lung Cancer: Additional Sources Of Information

Here are some reliable sources that can provide more information on lung cancer:

American Lung Association 
Phone: (800) 586-4872
http://www.lungusa.org

National Heart, Lung & Blood Institute Information Center 
Phone: (301) 251-1222
http://www.nhlbi.nih.gov/index.htm

The American Academy of Family Physicians 
http://familydoctor.org/

National Jewish Medical and Research Center 
Phone: 303/388-4461
Phone: 800/222-LUNG (5864)
http://www.njc.org/