Lung cancer, one of the most common forms of cancer that affects adults in the United States, can be classified broadly into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). The latter variety can be further classified into adenocarcinoma, squamous cell and large cell varieties. Conceptually, the difference between SCLC and NSCLC is the approach that is taken in both performing the diagnostic workup and the treatment planning. SCLC tends to be widely disseminated at its first presentation, thus favoring the use of chemotherapy as the mainstay of treatment. NSCLC, on the other hand, may be localized to the lung at the time of first presentation, favoring the use of surgical resection with or without radiation therapy as the initial mainstay of treatment. Each particular type of lung cancer has its own special characteristics, and more recently, its own genetic make up, allowing hope that new treatment modalities may be developed to improve the outcomes of patients affected with these diseases. Adenocarcinoma of the lung is a type of lung cancer.
Like other cancers, adenocarcinoma is the growth of abnormal cells. These cancerous cells multiply out of control and form a tumor. As the tumor grows, it destroys parts of the lung. Eventually, the tumor's abnormal cells can spread (metastasize) to other parts of the body, including the local lymph nodes in the chest and the central portion of the chest, called the mediastinum; the liver; the bones; the adrenal glands; and other organs, including the brain.
Adenocarcinoma is more likely than other types of lung cancer to be contained in one area of the body. If it is truly localized, it may also respond better than other lung cancers to treatment, especially surgical removal of the tumor and draining lymph nodes.
Adenocarcinoma is the most common form of lung cancer. Most of this type of cancer is found in smokers. However, it also is the most frequent type of lung cancer seen in nonsmokers. It is the most common form of lung cancer seen in women and people younger than 45.
As with other forms of lung cancer, you are more likely to get adenocarcinoma if you:
Smoke cigarettes � Smokers have 13 times more risk of developing lung cancer than nonsmokers. Cigarette smoke is associated with most cases of adenocarcinoma. Smoking is by far the leading risk factor for lung cancer, substantially more significant than all the following risk factors combined.
Breathe cigarette smoke � Nonsmokers who inhale the cigarette fumes of smokers have an increased risk of lung cancer.
Are exposed to radon gas � Radon is a colorless, odorless radioactive gas that is formed in the ground. It seeps into the lower floors of homes and public buildings and can contaminate drinking water. Radon exposure is the second leading cause of lung cancer. It's not clear whether elevated radon levels contribute to lung cancer in nonsmokers. However, research has shown that radon exposure contributes to increased rates of lung cancer in smokers and in people exposed to higher levels of radon, such as miners. You can test the levels of radon in your home and surrounding area by using commercially available radon testing kits.
Are exposed to asbestos � Asbestos is a fibrous mineral that is used in home insulation, fireproofing, tiles for floors and ceilings, automobile brake linings, and other products. It is believed that asbestos fibers can cause lung cancer. People at risk of lung cancer include workers who are exposed to asbestos on the job (miners, construction workers, shipyard workers and auto mechanics who work with brakes), and people who live or work in buildings in which building products that contain asbestos are deteriorating. In addition to the adenocarcinoma type of lung cancer, individuals who have been exposed to asbestos, and particular types of asbestos, are also at a significant greater risk of developing a specialized type of lung cancer called mesothelioma.
Are exposed to other carcinogens in the workplace � These include uranium, arsenic, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, diesel exhaust and high levels of talc dust.
Symptoms
Symptoms of adenocarcinoma are the same as for other forms of lung cancer. They can include:
- Cough - Coughing up blood - Wheezing - Shortness of breath - Discomfort during breathing - Chest pain - Fever and a mucus-producing cough - Discomfort during swallowing - Hoarseness - Weight loss and poor appetite - Other symptoms, if cancer has spread to the brain, bones or elsewhere - Certain types of lung cancer can also cause unusual growth of the fingers, called clubbing, in which the outer portions of the fingers look like little clubs
Diagnosis
Your doctor will ask you whether you smoke or whether you live with a smoker. If you smoke, your doctor will ask you how much you smoke and how long you have smoked. Your doctor also will ask whether you have worked in an industry where you may have been exposed to asbestos or other carcinogens.
Your doctor may suspect that you have some form of lung cancer based on your symptoms and your history. Your doctor will examine you, paying special attention to your lungs and chest. To confirm the diagnosis, your doctor will order a chest X-ray to see if there are any masses that could be cancer. If the X-ray shows anything suspicious, a computed tomography (CT) scan will be done to confirm the size and location of any mass or tumor. If cancer is suspected, further tests will be done to make the diagnosis, establish the specific type of lung cancer and determine how far it has spread. These tests may include:
- Sputum sample � In this test, coughed-up mucus is checked in the laboratory for cancer cells. With a test that evaluates the presence of cancer cells in the sputum. This is called sputum cytology.
- Biopsy � In this test, a sample of abnormal lung tissue is removed and examined under a microscope in a laboratory. Although this test often can be done using bronchoscopy, surgery sometimes is necessary to expose the suspicious lung area.
- Bronchoscopy � In this procedure, a tubelike instrument is passed into the lungs through the airways. The goal is to look for cancer inside of the lungs directly and to obtain a small piece of the lung for a biopsy.
- Mediastinoscopy � In this procedure, a tubelike instrument is used to biopsy lymph nodes or any masses seen between the lungs (the mediastinum). A biopsy obtained this way can diagnose the type of lung cancer and check to see if the cancer has spread to lymph nodes.
- Fine-needle aspiration � In this procedure, a tiny needle is inserted into a suspicious area of the lungs with the help of a CT scan done at the same time. The needle removes a small sample of tissue so it can be examined in a laboratory to diagnose the type of cancer.
- Thoracentesis � This procedure is used when lung cancer has caused fluid to accumulate in the chest. A sterile needle is used to withdraw a sample of the fluid so it can be examined in a laboratory.
- VATS (video-assisted thoracoscopy) � In this procedure, which can be both diagnostic and therapeutic, the surgeon places a flexible tube into an incision in the chest and can visually inspect the surrounding surfaces of the inner and outer linings of the lung area and even do surgery to remove abnormal areas. It is a less-invasive procedure compared to a larger operation, called a thoracotomy.
- CT, positron emission tomography (PET) and bone scans � These scans will check if lung cancer has spread to the brain, bones or other places in the body.
Expected Duration
Once it develops, adenocarcinoma of the lung will continue to grow and spread until it is treated.
Prevention
To reduce your risk of adenocarcinoma and other forms of lung cancer, you can:
- Avoid cigarette smoking � If you already smoke, ask your doctor about proven ways to help you quit.
- Avoid secondhand smoke � Choose smoke-free areas of restaurants and hotels. Also, ask guests to smoke outdoors, especially if there are children in your home.
- Reduce exposure to radon � Have your home checked for radon gas. A radon level above 4 picocuries/liter is unsafe. If you have a private well, have your drinking water tested for radon. Commercially available kits to test for radon are widely available.
- Reduce exposure to asbestos � Because there is no safe level of asbestos exposure, any exposure is too much. If you have an older home, check if any insulation or other material that contains asbestos is exposed or deteriorating. The asbestos in these areas must be removed or safely sealed away professionally. If the removal isn't done properly, you may be exposed to more asbestos than you would have been if it has been left alone. Workers who deal with asbestos-containing materials routinely should use approved measures to limit their exposure and to keep from bringing asbestos dust home on their clothing.
Treatment Surgery is the main treatment for all NSCL cancers if the cancer is contained in the chest and has no evidence of having spread to areas outside the chest. Three types of surgery can be used:
Wedge resection � Removal of only a small part of the lung Lobectomy � Removal of one lobe of the lung Pneumonectomy � Removal of the entire lung VATS (Video-assisted thoracoscopy) � In this procedure, which can be both diagnostic and therapeutic, the surgeon places a flexible tube into an incision in the chest and can visually inspect the surrounding surfaces of the inner and outer linings of the lung area and even do surgery to remove abnormal areas. It is a less-invasive procedure compared to a larger operation, called a thoracotomy. Since all of these surgical procedures require removal of a portion or the entire lung, and since many of the patients will have diminished lung function to begin with due to years of smoking, it is very important that a full evaluation of the existing lung function and the predicted lung function after an expected surgical removal be done. This is especially important for those with non cancerous abnormalities of their lungs, such as emphysema and chronic obstructive pulmonary diseases.
Depending on how far the cancer has spread (the stage), treatments can include chemotherapy and radiation therapy before and/or after surgery. Stages are defined by the size of the tumor and how far it has spread. Stages I through III are further divided into two "A" and "B" categories. Stage I tumors are small and have not invaded the surrounding tissue or organs. Stage II and III tumors have invaded surrounding tissue and/or organs and have spread to lymph nodes. Stage IV tumors have spread outside the chest area.
People with serious medical problems that make it difficult for them to withstand surgery may receive radiation therapy to shrink the tumor, or a combination of radiation and chemotherapy.
When the tumor has spread significantly, chemotherapy drugs may be recommended to slow the growth of the cancer even if it cannot cure the disease. Chemotherapy has been shown to decrease symptoms and prolong life in advanced cases of lung cancer.
Over the past decade, a series of new treatments has been developed specifically as a result of better understanding of the genetics of lung cancer and the specific abnormalities of the lung cancer cell. These agents are called targeted therapies, since they specifically target the abnormal biochemical pathways that are crucial in the development and growth of the cancer. In specialized centers, the lung cancer tissue that is removed may be tested for specific genetic (DNA) abnormalities and then treated accordingly.
Radiation therapy also may be recommended to relieve symptoms. The use of radiation is especially important in the treatment of lung cancer that has spread to the brain or that has spread to the bone and is causing pain. As mentioned above, it is also used alone or in combination with chemotherapy to treat the lung cancer that is located in the chest area as well.
When To Call a Professional
Call your doctor promptly if you have any of the symptoms of lung cancer, especially if you are a smoker or you have worked in an industry with high exposure to asbestos.
Prognosis
The outlook depends on the stage of the cancer and the overall health of the patient. In general, the prognosis is poor, especially if the lung cancer has spread to areas outside of the chest wall or has involved the lymph nodes of the mediastinum. This cancer can only be cured when surgery or radiation therapy can completely remove the tumor. However, many lung cancers are diagnosed at a stage when this is not possible. About 17% of people with adenocarcinoma survive more than 5 years after diagnosis.
Additional Info
National Cancer Institute (NCI) U.S. National Institutes of Health Public Inquiries Office Building 31, Room 10A03 31 Center Drive, MSC 8322 Bethesda, MD 20892-2580 Phone: 301-435-3848 Toll-Free: 1-800-422-6237 TTY: 1-800-332-8615 E-Mail: cancergovstaff@mail.nih.gov //www.nci.nih.gov/
American Cancer Society (ACS) 1599 Clifton Road, NE Atlanta, GA 30329-4251 Toll-Free: 1-800-227-2345 //www.cancer.org/
American Lung Association 61 Broadway, 6th Floor New York, NY 10006br />Phone: 212-315-8700 Toll-Free: 1-800-548-8252E-Mail: info@lungusa.org //www.lungusa.org/
National Heart, Lung, and Blood Institute (NHLBI) P.O. Box 30105 Bethesda, MD 20824-0105 Phone: 301-592-8573 TTY: 240-629-3255 Fax: 301-592-8563 E-Mail: nhlbiinfo@rover.nhlbi.nih.gov //www.nhlbi.nih.gov/
U.S. Environmental Protection Agency (EPA) Ariel Rios Building 1200 Pennsylvania Ave., N.W. Washington, DC 20460 Phone: 202-272-0167 //www.epa.gov/
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