Lung Cancer Diagnosis

  • Diagnosis

    Lung cancer is the uncontrolled growth of abnormal cells in the lung. Figure 01. There are two main types of lung cancer: non-small cell cancer and small cell cancer. Diagnosis, treatment and prognosis differ for small cell and non-small cell lung cancers.

    Lung cancer causes more death than any other form of cancer in both men and women.

    Smoking cigarettes is the number one cause of lung cancer. Of particular importance is the fact that teenage girls are the fastest growing group of smokers in the U.S. and that women seem to be more susceptible to the disease than men. Unfortunately, the number of cases of lung cancer is rapidly increasing in other parts of the world, as many people in third world countries are not aware of the dangers of smoking.

    Cancer can grow in the lungs for many years before it is detected. Often people do not have symptoms until the disease has progressed, during which time the cancer grows undetected.

    Each type of lung cancer varies depending on where it forms in the lungs.

    Click to enlarge: Anatomy of the Lungs

    Figure 01. Anatomy of the Lungs

    Smoking tobacco products causes most cases of lung cancer. Approximately 90% of all lung cancers occur in people who either currently smoke, or who used to smoke. However, anyone, even nonsmokers, can get lung cancer.

    Tobacco smoke contains many substances known to damage lung cells and promote tumor growth. Women seem to be more susceptible to these cancer-causing agents than men. Even nonsmoking women are more likely to get lung cancer than nonsmoking men.

    Exposure to toxic chemicals can damage the lungs and give rise to some lung cancers. Certain chemicals are known to cause lung cancer. If you have been exposed to asbestos, uranium, arsenic, nickel, radon gas, chromium compounds, chloromethyl ether, vinyl chloride, coal products, or mustard gas, especially in a work setting, you should inform your doctor.

    Air pollution is also thought to increase the risk of lung cancer.

    Approximately 75% to 85% of lung cancers are non-small cell cancers. The non-small cell cancers are further divided into subgroups Table 01.

    Table 1.  Types of Non-small Cell Lung Cancer (Carcinoma)

    Adenocarcinoma is the most common non-small cell cancer of the lung; it is often seen in nonsmokers and women. You probably will not have any symptoms when the cancer is found on a chest x-ray.
    Squamous cell carcinoma is the type of lung cancer that smokers tend to get. It sometimes located near or in a major airway, so the cancer can cause symptoms earlier in its growth. Coughing, producing bloody phlegm (sputum), shortness of breath, or pneumonia are common symptoms. It usually does not spread to distant sites in the body. It is more likely than other types of lung cancers to be cured with surgery.
    Large cell carcinomas represent about 10% of non-small cell cancers of the lung. It grows and spreads quickly, often spreading to other parts of the body including the brain. Large cell carcinoma does not have the specific features (such as cell shape or location of growth) of any of the other lung cancer cell types mentioned. Frequently it will turn out to be one of the subtypes if further tissue is obtained.

    Small cell carcinomas are almost always found in patients who are smokers. They are the most aggressive types of lung cancers. Small cell cancer (sometimes called oat cell cancer) accounts for 15% to 25% of the lung cancer cases diagnosed annually. Symptoms don't usually develop until the cancer has progressed significantly.

    Small cell cancers rapidly grow and spread (metastasize) to distant sites, and often have spread by time of discovery. Although both types of lung cancer are dangerous, prognosis for small cell cancer is usually worse than prognosis for non-small cell cancer.

    Symptoms of lung cancer vary according to what type of lung cancer you have and where it is located in the lungs. Some symptoms of lung cancer, when and if they occur, are persistent coughing, shortness of breath, blood in the sputum and wheezing.

    Symptoms of lung cancer don't usually occur until the disease has become significantly worse. Symptoms may be noticed once the cancerous mass of cells, called a tumor (carcinoma) has increased in size, invaded surrounding tissue, or spread to other parts of the body. Persistent coughing, shortness of breath, coughing up blood, and wheezing are possible symptoms. Recurring pneumonia may be a sign of cancer, and deserves further investigation. If the cancer has spread to surrounding tissue, you may also experience chest or shoulder pain, hoarseness, and difficulty swallowing. If it has reached other parts of the body, weight loss, fatigue, bone pain, yellowing of the skin, lumps under the skin, weakness in the arms and legs, headaches, seizures, and other symptoms may occur, depending on where the tumor has metastasized.

    You may experience different symptoms depending on the disease's progression and what type of lung cancer you have Table 02.

    Table 2.  Potential Symptoms of Lung Cancer According to Stage

    Local (small area of lung) Cancer has spread within the lung Cancer has spread to other body systems
    Shortness of breath Shortness of breath Weight loss, often dramatic, leading to sunken eyes and hollow cheeks
    Spitting up blood Cough Fatigue
    Chest pain Spitting up blood Bone pain
    Pneumonia Pneumonia Yellowing of the skin caused by a liver malfunction (jaundice).
    ? Chest pain Pain in the liver
    ? Inflammation of the tissue that surrounds the lungs (pleurisy) Skin lesions
    ? Shoulder pain Headache

    Smoking cigarettes contributes to more cases of lung cancer than any other cause. Long-term smokers face a lung cancer risk 20 times greater than nonsmokers. The odds increase for heavier smokers. Changing to low-tar cigarettes, cigars, or pipes does not decrease the danger. Your risk decreases significantly five years after smoking your last cigarette, and after 10 to 15 years, you begin to get close to the level of a nonsmoker. Stopping smoking, even later in life, benefits your health, although the earlier you quit the better.

    Women exposed to the same amount of smoke as men are more likely to develop lung cancer. Exposure to asbestos or other industrial chemicals increases your odds of developing lung cancer. If you have worked as a ship builder, as a miner, or you manufacture or repair brakes, you may have been exposed to large amounts of harmful toxins, which increases your risk three to four-fold. If you work with harsh toxins and you smoke, your chance of getting lung cancer is even higher.

    Family members of people with lung cancer are at greater risk for the disease. Siblings and offspring of lung cancer patients have a slightly higher chance of developing the disease, which could be due to genetics. If the lung cancer patient is a smoker, the increased risk may be due to secondhand smoke. If you are a smoker, you put your family members at greater risk by exposing them to your cigarette smoke.

    Your risk for lung cancer increases with age. A previous diagnosis of cancer and scarring of the lungs after pneumonia or tuberculosis also increases your risk.

    Most cases of lung cancer are diagnosed in people between the ages of 55 and 65. It is not often seen in younger people, although it has happened. If you have had cancer before, you are at greater risk of developing it again than someone who has never had it. This is true of all cancers. Having chronic obstructive lung diseases, such as emphysema or chronic bronchitis puts you at greater risk for lung cancer. Both of these diseases are linked to heavy cigarette smoking.

    Secondhand smoke increases your chances for developing lung cancer, putting spouses and those working in smoke-filled environments at greater risk. Air pollution and vitamin deficiencies also may contribute to the disease.

    Lung cancer is often diagnosed by having a chest x-ray as part of a routine screening or preceding a surgical procedure. If there is a spot or a mass on the x-ray of you lungs, your doctor will identify it as a lesion and will want to investigate further.

    If you have symptoms, or if a suspicious lesion shows up on an x-ray, you will receive a complete physical exam, diagnostic tests, and a biopsy to determine if the problem is caused by cancer Figure 02. A very accurate picture of suspected cancerous tissue can be taken in order to get a better look at a lesion. Using a computed tomography scan (CT scan), x-ray photographs are taken from different angles. A computer then combines the pictures into one complete picture. CT scans can help determine size, position, features, and lymph node involvement. Doctors may use computed tomography to guide a needle into the lung to remove a tissue specimen from the tumor. This process is called a biopsy, and is used to test the tissue for the presence of cancer cells.

    Bronchoscopy is another method used for diagnosis. Your doctor can look into your lungs through a special fiber-optic tube (bronchoscope) inserted through your nose or mouth and down the windpipe. This test can help your doctor determine what state the tumor is in. A local anesthesia is used to relax the nostril and throat muscles, so you may feel fluid running down the back of the throat and need to cough or gag until the anesthetic begins working. You may be required to stay in the hospital overnight. After the test, your throat may hurt or feel scratchy, but you will be able eat and drink normally after about two hours.

    Bone scans and other diagnostic procedures may be ordered to determine how advanced the cancer has become. Brain and abdominal CT scans are often performed, to check for cancer that has spread.

    Once you have been diagnosed, your doctor will categorize your cancer into a stage in order to determine treatment options and prognosis. Staging is a method of classifying the tumor by size, location, and the extent to which the cancer has spread (metastasis).

    There are four stages for non-small cell lung cancer. The five-year survival rates assigned to each stage are averages. You should remember that everyone responds differently to cancer and its treatment and that survival rates always vary. For non-small cell cancers, most practitioners follow a system that is used worldwide. The system takes into account size and location of the tumor, the lymph node involvement and whether or not the tumor has spread (metastasis). Depending on the stage, removing the tumor may or may not be possible.

    Stage 0 non-small cell lung cancer is also called carcinoma in situ (in place, or “localized” cancer). This cancer is limited to a few layers of cells in one area of the lung. It has not penetrated the lining of the lung, or the lung tissue. The cancer can be cured with surgery alone.

    Stage I non-small cell lung cancer is limited to the lung only. Surgery is the preferred method of treatment for this stage, which is further divided in to IA and IB.

    • Stage IA About 13% of all non-small cell lung cancers are diagnosed at this stage. The tumor is small, and there is no lymph node involvement, nor has it spread to other locations. The five year survival rate is 67%.
    • Stage IB about 23% of non-small cell lung cancers are diagnosed at this stage. The tumor is slightly larger than at state IA, but it still has not spread to other tissues, nor is there lymph node involvement. The five year survival rate is 57%.

    Stage II non-small cell lung cancer has spread to nearby lymph nodes. Surgery is still the primary method used to treat it.

    • Stage IIA is when the tumor is still small, there is some lymph node involvement, but it has not spread. It has a survival rate of 55%
    • Stage IIB is when the tumor is a bit larger, there is either some or no lymph node involvement and it has not spread. It has a survival rate of 39%.

    Stage III non-small cell lung cancer has spread to the chest wall, the diaphragm, or to the lymph nodes in the space between the chest bone and in front of the heart (mediastinum), on the other side of the chest, or near the lungs. This stage is further divided into two stages:

    • Stage IIIa: may be removed with surgery in some cases. Chemotherapy and radiation may be used. The average five-year survival is from 15% to 35%.
    • Stage IIIb: cannot be removed by surgery. Chemotherapy and radiation combinations are commonly used to prolong survival. The average five-year survival is 5%.

    Stage IV non-small cell lung cancer has spread to distant sites in the body. The average five-year survival is less than 5%.

    There are two stages for small cell cancer: limited and extensive. Small cell lung cancer is usually found in people who smoke or who used to smoke cigarettes.

      Limited stage small cell lung cancer is limited to one side of the chest (one lung and in nearby lymph nodes). About 40% of small cell lung cancer patients fall into the limited stage. Average survival is 14 to 21 months with current treatments, with most people surviving 16 to 18 months. Two-year survival for limited disease is about 20%.

      Extensive stage small cell lung cancer has spread beyond one lung to other parts of the body. Average survival for extensive stage disease is 6 to 12 months with current treatments. Two-year survival for limited stage disease is less than 4%.

    Click to enlarge: Lung needle biopsy

    Figure 02. Lung needle biopsy

    Not smoking and avoiding contact with secondhand smoke offers the most effective means of preventing lung cancer. Giving up the habit significantly lowers but does not completely eliminate the risk. No one can completely eliminate the risk of lung cancer, but not smoking is the best step you can take to protect yourself.

    Some doctors advise regular screening for smokers and former smokers. There are several different ways of screening for lung cancer. Sputum cytology, a method used to analyze cells the patient coughs up, can determine the presence of malignant cells, but not the location of the tumor. Sputum cytology followed by a bronchoscopy or CT scan offers the best prospect for picking up lesions before they spread. Spiral CT, a type of noninvasive diagnostic scan, has picked up malignancies in patients without symptoms and may be used for screening. The test takes about 15 to 20 seconds. The one drawback of the test is that the scans may indicate nonmalignant abnormalities, which would prompt the doctor to order a biopsy. A biopsy of the lung is invasive, involving the insertion of a needle through the chest wall into the lung. A recent study involving thousands of patients looked at the benefits of using CT scans to screen all smokers. The study showed that the CT scans picked up enough early cancers that could be treated that it provides a survival benefit. But screeing all adult smokers regularly with CT scans would be very expensive, and some experts wonder if a significant number of people would have unnecessary lung surgery.

  • Prevention and Screening

    Not smoking and avoiding contact with secondhand smoke offers the most effective means of preventing lung cancer. Giving up the habit significantly lowers but does not completely eliminate the risk. No one can completely eliminate the risk of lung cancer, but not smoking is the best step you can take to protect yourself.

    Some doctors advise regular screening for smokers and former smokers. There are several different ways of screening for lung cancer. Sputum cytology, a method used to analyze cells the patient coughs up, can determine the presence of malignant cells, but not the location of the tumor. Sputum cytology followed by a bronchoscopy or CT scan offers the best prospect for picking up lesions before they spread. Spiral CT, a type of noninvasive diagnostic scan, has picked up malignancies in patients without symptoms and may be used for screening. The test takes about 15 to 20 seconds. The one drawback of the test is that the scans may indicate nonmalignant abnormalities, which would prompt the doctor to order a biopsy. A biopsy of the lung is invasive, involving the insertion of a needle through the chest wall into the lung. A recent study involving thousands of patients looked at the benefits of using CT scans to screen all smokers. The study showed that the CT scans picked up enough early cancers that could be treated that it provides a survival benefit. But screeing all adult smokers regularly with CT scans would be very expensive, and some experts wonder if a significant number of people would have unnecessary lung surgery.

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