Lung Cancer

What is Lung Cancer?

Lung cancer is a cancer starts in the lungs. In order to understand lung cancer, it helps to know about the normal structure and function of the lungs.

The lungs are two sponge-like organs found in the chest. The right lung has 3 sections, called lobes. The left lung has 2 lobes, as shown in the picture below. The left lung is smaller because the heart takes up more room on that side of the body. The lungs bring air in and out of the body, taking in oxygen and getting rid of carbon dioxide gas, a waste product.

The lining around the lungs, called the pleura, helps to protect the lungs and allows them to move during breathing. The windpipe (trachea) brings air down into the lungs. It divides into tubes called bronchi (singular, bronchus) which divide into smaller branches called bronchioles.
At the end of these small branches are tiny air sacs known as alveoli.

Most lung cancer starts in the lining of the bronchi, but it can also start in other parts of the lung. Lung cancer often takes many years to develop. First, there may be areas of pre-cancerous changes in the lung. These changes are not a mass or tumor. They can’t be seen on an x-ray and they don’t cause symptoms.

Over time, these pre-cancerous areas may go on to become true cancer and make chemicals that cause new blood vessels to form nearby. These new blood vessels nourish the cancer cells and allow a tumor to form. Finally, the tumor becomes large enough to show up on an x-ray.
At some point, cancer cells can break away and spread to other parts of the body in a process called metastasis. Lung cancer is a life-threatening disease because it often spreads in this way before it is found.

One of the ways lung cancer can spread is through the lymphatic system. Lymphatic vessels are like veins but carry lymph fluid instead of blood. Lymph is a clear fluid that contains tissue waste products and immune system cells. Lung cancer cells can enter lymphatic vessels and begin to grow in lymph nodes around the bronchi and in the the area between the lungs. When lung cancer cells have reached the lymph nodes, they are more likely to have spread to other organs of the body too. Staging and decisions about lung cancer treatment are based on whether or not the cancer has spread to the nearby lymph nodes.

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Why is lung cancer a concern for American Indians?

While fewer Native Americans get diagnosed with lung cancer, individuals who work in uranium minining, asbestos removal and who are exposed to second hand smoke are at risk for developing lung cancer.

Lung Cancer Stats
Incidence: According to Hawaii SEER Registry 1977-83, Native Hawaiian female lung and bronchus cancer incidence rate is the highest of any racial group at 45.8 (white female rate is 33.3).

The Alaska Native female lung cancer incidence rate is 23.2 (State of Alaska, 1969-83). 

According to the New Mexico SEER Registry (1977-83), lung cancer incidence rates of American Indian females living in Arizona and New Mexico is the lowest of any racial group with a rate of 4.4. 

Examples of female tribal and IHS Area lung cancer incidence rates follow (IHS, 1982-87): 

Athabascan Alaska Natives (111.3), Aleut Alaska Natives (101.7), Eskimo Alaska Natives (53.2), Alaska IHS Area (58.4), Bemidji IHS Area (52.3), Billings HIS Area (37.8), Aberdeen IHS Area (32.1), Eastern Band Cherokee Tribe (35.2), and Sioux Tribes (34.1). 
(Nutting, et al., "Cancer in American Indians and Alaska Natives, 1982-87," AJPH, 1993)

Mortality:  Native Hawaiian women have the highest lung cancer mortality rates (35.3) of any race (Hawaii SEER Registry, 1977-83). Alaska Native women have a rate of 15.0 and white women are 20.9. According to the National Center for Health Statistics death records, the age-adjusted American Indian female lung cancer mortality rates are among the lowest of any race with a rate of 9.3.  However, as geographic areas indicate rates which are higher than those reported in NCHS.  IHS age-adjusted lung cancer mortality rates (1984-88) for females follow:  Alaska IHS Area (68.5), Billings IHS Area (65.7), Aberdeen IHS Area (45.0), Bemidji IHS Area (40.7), and Nashville HIS Area (25.1).
(IHS, Cancer Mortality among Native Americans in the United States, 1992, p. 34)

Survival:  Survival data are not available for Alaska Natives. American Indian women living in New Mexico and Arizona have a poorer lung cancer survival rate (14.1) than do white women (17.1).  Native Hawaiian women have a five-year relative survival rate of 17.0. (NCI, Report of the Special Action Committee, 1992, p. A-10)

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What causes lung cancer?

There are many risk factors that increase the likelihood of developing lung cancer.

• Tobacco Smoke - Smoking is by far the leading risk factor for lung cancer. Tobacco smoke causes more than nearly 9 out of 10 cases of lung cancer. The longer a person has been smoking and the more packs per day smoked, the greater the risk. If a person stops smoking before lung cancer develops, the lung tissue slowly returns to normal. Stopping smoking at any age lowers the risk of lung cancer.
  
  
• Cigar and pipe smoking are almost as likely to cause lung cancer as is cigarette smoking. There is no evidence that smoking low tar or "light" cigarettes is safer than smoking regular cigarettes or reduces the risk of lung cancer.
  
  
• Second hand smoke -People who don’t smoke but who breathe the smoke of others may also be at a higher risk for lung cancer. Non-smoking spouses who live with a smoker, for example, have about a 20% to 30% greater risk of developing lung cancer than do spouses of non-smokers. Non-smokers exposed to tobacco smoke in the workplace are also more likely to get lung cancer.
  
  
• Hookah smoking has become popular among young people in recent years. It is often marketed as being safer than cigarettes. Although there is less tobacco in the product used for hookahs, it is still dangerous and addictive. And hookah smoking may lead to cigarette smoking in the future.
  
  
• Radon- Radon is a radioactive gas made by the natural breakdown of uranium, which is found at higher than normal levels in the soil in some parts of the United States. Radon can't be seen, tasted, or smelled. It can become concentrated indoors and create a possible risk for cancer. Smokers are especially sensitive to the effects of radon. State and local offices of the EPA (Environmental Protection Agency) can give you information on how to test for radon in the home. The document, Radon, with more detail is available from the ACS.
  
  
• Asbestos- Asbestos exposure is another risk factor for lung cancer. People who work with asbestos have a higher risk of getting lung cancer. If they smoke too, the risk is greatly increased. Both smokers and non-smokers exposed to asbestos also have a greater risk of developing a type of cancer (called mesothelioma) that starts in the lining of the lungs. Although asbestos was used for many years, the government has now nearly stopped its use in the workplace and in home products. While it is still present in many buildings, it is not thought to be harmful as long as it is not released into the air.
  
  
• Other Cancer-causing Agents in the Workplace- Other things that cause cancer (cancer-causing agents) found in the workplace that can increase lung cancer risk include:
  • radioactive ores such as uranium 
  • inhaled chemicals or minerals such as arsenic, beryllium, cadmium, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, and chloromethyl ethers
  • diesel exhaust.
  
  
• Radiation Treatment to the Lungs- People who have had radiation to the chest to treat another cancer are at higher risk for lung cancer, especially if they smoke. Non-smoking women who have radiation to the breast after a lumpectomy for breast cancer do not have a higher risk of lung cancer unless they also smoke.
  
  
• Arsenic- High levels of arsenic in drinking water may increase the risk of lung cancer. The effect is even greater for smokers.
  
  
• Certain Diseases- Diseases such as silicosis and berylliosis (caused by breathing in certain minerals) also increase the risk of lung cancer.
  
  
• Personal and Family History- If you have had lung cancer, you have a higher risk of getting another lung cancer. Brothers, sisters, and children of people who have had lung cancer may have a slightly higher risk themselves. Research is being done on this.
  
  
• Diet and Vitamins- Some reports suggest that a diet low in fruits and vegetables might increase the risk of lung cancer in people who are exposed to tobacco smoke. It may turn out that fruits and vegetables help protect against lung cancer. On the other hand, two studies have found that smokers who took beta carotene supplements actually had an increased risk of lung cancer. The results of these studies suggest that smokers should avoid taking beta carotene supplements.
  
  
• Air Pollution- In cities, air pollution may slightly increase the risk of lung cancer. But the risk is still far less than that caused by smoking.
  
  
• Marijuana- Medical reports suggest that marijuana could cause cancers of the mouth and throat. But because marijuana is an illegal substance it is not easy to gather information about its effects on the body. Marijuana cigarettes have more tar than regular cigarettes. Many of the cancer-causing substances in tobacco are also found in marijuana. Marijuana is also inhaled very deeply and the smoke is held in the lungs for a long time. For these reasons it is thought that smoking marijuana may increase lung cancer risk.
  
  
• DNA and Gene Changes- During the past few years, scientists have made great progress in understanding how risk factors produce certain changes in the DNA of lung cells, causing the cells to become cancerous. DNA is the genetic material that carries the instructions for nearly everything our cells do.

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What are some of the various types of lung cancer?

There are 2 main types of lung cancer and they are treated differently.

• small cell lung cancer (SCLC)
• non-small cell lung cancer (NSCLC)

If the cancer has features of both types, it is called mixed small cell/large cell cancer. Other types of tumors can grow in the lungs, too. Some of these are not cancer and others are cancerous. Carcinoid tumors, for example, are slow-growing and usually cured by surgery.

Small Cell Lung Cancer (SCLC)
About 10% to 15% of all lung cancers are the small cell lung cancer (SCLC), named for the small cells that make up these cancers. Other names for SCLC are oat cell carcinoma and small cell undifferentiated carcinoma.

SCLC often starts in the bronchi near the center of the chest, and it tends to spread widely through the body fairly early in the course of the disease. The cancer cells can multiply quickly, form large tumors, and spread to lymph nodes and other organs, such as the bones, brain, adrenal glands, and liver. This is important because it means that surgery is rarely an option (and never the only treatment given). Treatment must include drugs to try to kill the widespread disease.

Small cell lung cancer is almost always caused by smoking. It is very rare for someone who has never smoked to have small cell lung cancer.

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Non-Small Cell Lung Cancer (NSCLC)
About 85% to 90% of all lung cancers are of the non-small cell type. There are 3 sub-types of NSCLC. The cells in these sub-types differ in size, shape, and chemical make-up.

• Squamous cell carcinoma: About 25% to 30% of all lung cancers are this kind. They are linked to smoking and tend to be found in the middle of the lungs, near a bronchus.
• Adenocarcinoma: This type accounts for about 40% of lung cancers. It is usually found in the outer part of the lung.
• Large-cell (undifferentiated) carcinoma: About 10% to 15% of lung cancers are this type. It can start in any part of the lung. It tends to grow and spread quickly, which makes it harder to treat.

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What are the risk factors of lung cancer?

Risk factors for both Non-Small Cell and Small Cell Lung Cancer include:

• Tobacco Smoke
• Radon
• Asbestos
• Other Cancer-causing Agents in the Workplace
• Radiation Treatment to the Lungs
• Arsenic
• Certain Diseases
• Personal and Family History
• Diet and Vitamins
• Air Pollution
• Marijuana
• DNA and Gene Changes

Other Small Cell Lung Cancer Risk Factors:

Certain Other Mineral Exposures- Silicosis and berylliosis are lung diseases caused by breathing in certain minerals. They are seen mainly in certain occupations such as mining. People with these conditions also have a higher risk of lung cancer.

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What can you do to prevent getting lung cancer?

Non-Small Cell Lung Cancer- Some people who get lung cancer do not have any known risk factors. Although we know how to prevent most lung cancers, at this time we don't know how to prevent all of them. The best way to prevent lung cancer is not to smoke. If you already smoke, you should try to quit. You should also avoid breathing in other people's smoke.

A good diet with lots of fruits and vegetables may also help prevent lung cancer.

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Small Cell Lung Cancer- Radon is an important cause of lung cancer. You can reduce or eliminate your exposure to radon by having your home tested and treated, if needed.

It is also helpful to avoid being exposed to known cancer-causing chemicals, in the workplace and elsewhere. People working where these exposures are common should try to keep exposure to a minimum.

A healthy diet with lots of fruits and vegetables may also help prevent lung cancer.
Attempts to reduce the risk of lung cancer in current or former smokers by giving them high doses of vitamins or vitamin-like drugs have not been successful. In fact, some studies have found that beta-carotene, a nutrient related to vitamin A, appears to increase the rate of lung cancer in these people.

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What are the signs/symptoms of lung cancer?

Symptoms of lung cancer are varied dependent upon where and how widespread the tumor is. Warning signs of lung cancer are not always present or easy to identify. A person with lung cancer may have the following kinds of symptoms:

• No symptoms: In up to 25% of people who get lung cancer, the cancer is first discovered on a routine chest x-ray or CT scan as a solitary small mass sometimes called a coin lesion. These patients with small single masses often report no symptoms of lung cancer at the time it is discovered.
  
  
• Symptoms related to the cancer: The growth of the cancer and invasion of lung tissues and surroundings may interfere with breathing, leading to symptoms such as cough, shortness of breath, wheezing, chest pain, and coughing up blood (hemoptysis). If the cancer has invaded nerves, for example, it may cause shoulder pain that travels down the outside of the arm (called Pancoast's Syndrome) or paralysis of the vocal cords leading to hoarseness. Invasion of the esophagus may lead to difficulty swallowing (dysphagia). If a large airway is obstructed, collapse of a portion of the lung may occur and cause infections (abscesses, pneumonia) in the obstructed area.
  
  
• Symptoms related to metastasis: Lung cancer that has spread to the bones may produce excruciating pain at the sites of bone involvement. Cancer that has spread to the brain may cause a number of neurologic symptoms that may include blurred vision, headaches, seizures, or symptoms of stroke such as weakness or loss of sensation in parts of the body.
  
  
• Paraneoplastic symptoms: Lung cancers frequently are accompanied by so-called paraneoplastic syndromes that result from production of hormone-like substances by the tumor cells. Paraneoplastic syndromes occur most commonly with SCLC but may be seen with any tumor type. A common paraneoplastic syndrome associated with SCLC is the production of a hormone called adrenocorticotrophic hormone (ACTH) by the cancer cells, leading to over secretion of the hormone cortisol by the adrenal glands (Cushing's syndrome). The most frequent paraneoplastic syndrome seen with NSCLC is the production of a substance similar to parathyroid hormone, resulting in elevated levels of calcium in the bloodstream.
  
  
• Nonspecific symptoms: Nonspecific symptoms seen with many cancers including lung cancers include weight loss, weakness, and fatigue. Psychological symptoms such as depression and mood changes are also common.

When should one consult a doctor? One should consult a health care provider if they develop the symptoms associated with lung cancer, in particular, if they have:

• A new persistent cough or worsening of an existing chronic cough,
• Blood in the sputum,
• Persistent bronchitis or repeated respiratory infections,
• Chest pain,
• Unexplained weight loss and/or fatigue, and/or
• Breathing difficulties such as shortness of breath or wheezing.

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How is lung cancer detected?

Doctors use a wide range of diagnostic procedures and tests to diagnose lung cancer. These include:

• The history and physical examination may reveal the presence of symptoms or signs that are suspicious for lung cancer.
  
  
• The chest x-ray is the most common first diagnostic step when any new symptoms of lung cancer are present.
  
  
• CT (computerized axial tomography scan, or CAT scan) scans may be performed on the chest, abdomen, and/or brain to examine for both metastatic and primary tumor. A CT scan of the chest may be ordered when x-rays are negative or do not yield sufficient information about the extent or location of a tumor. CT scans are x-ray procedures that combine multiple images with the aid of a computer to generate cross-sectional views of the body.
  
  
• A technique called a low-dose helical CT scan (or spiral CT scan) is sometimes used in screening for lung cancers. This procedure requires a special type of CAT scanner and has been shown to be an effective tool for the identification of small lung cancers in smokers and former smokers.
  
  
• Magnetic resonance imaging (MRI) scans may be indicated when precise detail about a tumor's location is required. The MRI technique uses magnetism, radio waves, and a computer to produce images of body structures.
  
  
• Positron emission tomography (PET) scanning is a specialized imaging technique that uses short-lived radioactive substances to produce three-dimensional colored images of those substances functioning within the body. While CT scans and MRI scans look at anatomical structures, PET scans measure metabolic activity and functioning of tissue. PET scans can determine whether a tumor tissue is actively growing and can aid in determining the type of cells within a particular tumor.
  
  
• Bone scans are used to create images of bones on a computer screen or on film. Doctors may order a bone scan to determine whether a lung cancer has metastasized to the bones. In a bone scan, a small amount of radioactive material is injected into the bloodstream and collects in the bones, especially in abnormal areas such as those involved by metastatic tumors.
  
  
• Sputum cytology: The diagnosis of lung cancer always requires confirmation of malignant cells by a pathologist, even when symptoms and x-ray studies are suspicious for lung cancer. The simplest method to establish the diagnosis is the examination of sputum under a microscope. If a tumor is centrally located and has invaded the airways, this procedure, known as a sputum cytology examination, may allow visualization of tumor cells for diagnosis.
  
  
• Bronchoscopy: Examination of the airways by bronchoscopy (visualizing the airways through a thin probe inserted in a tube through the nose or mouth) may reveal areas of tumor that can be sampled for pathologic diagnosis. A tumor in the central areas of the lung or arising from the larger airways is accessible to sampling using this technique.
  
  
• Needle biopsy: Fine needle aspiration (FNA) through the skin, most commonly performed with radiological imaging for guidance, may be useful in retrieving cells for diagnosis from tumor nodules in the lungs. Needle biopsies are particularly useful when the lung tumor is peripherally located in the lung and not accessible to sampling by bronchoscopy. A small amount of local anesthetic is given prior to insertion of a thin needle through the chest wall into the abnormal area in the lung. Cells are suctioned into the syringe and are examined under the microscope for tumor cells.
  
  
• Thoracentesis: Sometimes lung cancers involve the lining tissue of the lungs (pleura) and lead to an accumulation of fluid in the space between the lungs and chest wall (called a pleural effusion). Aspiration of a sample of this fluid with a thin needle (thoracentesis) may reveal the cancer cells and establish the diagnosis.
  
  
• Major surgical procedures: If none of the aforementioned methods yields a diagnosis, surgical methods must be employed to obtain tumor tissue for diagnosis. These can include mediastinoscopy (examining the chest cavity between the lungs through a surgically inserted probe with biopsy of tumor masses or lymph nodes) or thoracotomy (surgical opening of the chest wall with removal of as much tumor as possible).
  
  
• Blood tests: While routine blood tests alone cannot diagnose lung cancer, they may reveal biochemical or metabolic abnormalities in the body that accompany cancer. For example, elevated levels of calcium or of the enzyme alkaline phosphatase may accompany cancer that is metastatic to the bones. Likewise, elevated levels of certain enzymes normally present within liver cells, including aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT), signal liver damage, possibly through the presence of metastatic tumor.
  

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What treatments are available for lung cancer?

If you have lung cancer, your treatment choices may include surgery, radiation therapy, chemotherapy, or targeted therapy. More than one kind of treatment may be used, depending on the stage of your cancer.

Surgery is usually recommended (often along with other treatments) for early stage lung cancers. If surgery can be done, it gives the best chance of curing NSCLC.
Many different operations can be used to treat (and maybe cure) non-small cell lung cancer:

• pneumonectomy (new-mo-nek-tuh-me): the entire lung is removed in this surgery. 
• lobectomy (lobe-ek-tuh-me): a section (lobe) of the lung is removed in this surgery. 
• segmentectomy (seg-men-tek-tuh-me) or wedge resection: part of a lobe is removed in this surgery.

With any of these operations, lymph nodes are also removed to look for possible spread of the cancer.

Radiation therapy is treatment with high-energy rays (such as x-rays) to kill or shrink cancer cells. The radiation may come from outside the body (external radiation) or from radioactive materials placed into or next to the tumor (brachytherapy). External radiation is the type most often used to treat lung cancer.

Radiation is sometimes used as the main treatment of lung cancer. It might be used for people who are not healthy enough to have surgery. For other patients, radiation might be used after surgery to kill small areas of cancer that can't be seen and removed during surgery. Radiation can also be used to relieve symptoms such as pain, bleeding, trouble swallowing, or problems caused by the cancer spreading to the brain.

Chemotherapy- Chemotherapy (often called simply "chemo") is treatment with anti-cancer drugs injected into a vein or taken by mouth. These drugs enter the bloodstream and go throughout the body, making this treatment useful for cancer that has spread (metastasized) to organs beyond the lung. Doctors give chemo in cycles, with each period of treatment followed by a rest period to allow the body time to recover. Chemo cycles generally last about 3 to 4 weeks, and the first round of treatments typically involves 4 to 6 cycles.

Other Treatments:
At times, treatments other than surgery or radiation therapy may be used to destroy lung cancer cells in certain places.

Radiofrequency Ablation (RFA)- This method is being studied for small lung tumors that are near the outer edge the lungs, especially in people who can't have or don't want surgery. It uses high-energy radio waves to heat the tumor. A thin, needle-like probe is placed through the skin and advanced until the end is in the tumor. Once it is in place, an electric current is passed through the probe, which heats the tumor and destroys the cancer cells.

Photodynamic Therapy (PDT)- Photodynamic therapy is sometimes used to treat smaller lung cancers near airways when other treatments aren't a good choice, or to help open up airways blocked by tumors to help people breathe better.  In this approach, a light-activated drug called Photofrin is injected into a vein. Over the next couple of days, the drug collects in cancer cells. A bronchoscope is passed down the throat and into the lung. A special red light on the end of the bronchoscope is aimed at the tumor. It turns on the drug there which causes the cells to die.

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Clinical trials- are carefully controlled research studies that are done with patients. These studies test whether a new treatment is safe and how well it works in patients, or they may test new ways to diagnose or prevent a disease. Clinical trials have led to many advances in cancer prevention, diagnosis, and treatment.

Clinical trials are done to get a closer look at promising new treatments or procedures in patients. A clinical trial is only done when there is good reason to believe that the treatment, test, or procedure being studied may be better than the one used now. Treatments used in clinical trials are often found to have real benefits and may go on to become tomorrow's standard treatment.

Clinical trials can focus on many things, such as:

• new uses of drugs that are already approved by the US Food and Drug Administration (FDA) 
• new drugs that have not yet been approved by the FDA 
• non-drug treatments (such as radiation therapy) 
• medical procedures (such as types of surgery) 
• herbs and vitamins 
• tools to improve the ways medicines or diagnostic tests are used 
• medicines or procedures to relieve symptoms or improve comfort 
• combinations of treatments and procedures

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